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  • 1
    ISSN: 1572-9729
    Keywords: bioremediation ; Dehalococcoides ; dechlorination ; microcosm ; tetrachloroethane ; trichloroethene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study investigated the biotransformation pathways of 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA) in the presence of chloroethenes (i.e. tetrachloroethene, PCE; trichloroethene, TCE) in anaerobic microcosms constructed with subsurface soil and groundwater from a contaminated site. When amended with yeast extract, lactate, butyrate, or H2 and acetate, 1,1,2,2-TeCA was initially dechlorinated via both hydrogenolysis to 1,1,2-trichloroethane (1,1,2-TCA) (major pathway) and dichloroelimination to dichloroethenes (DCEs) (minor pathway), with both reactions occurring under sulfidogenic conditions. In the presence of only H2, the hydrogenolysis of 1,1,2,2-TeCA to 1,1,2-TCA apparently required the presence of acetate to occur. Once formed, 1,1,2-TCA was degraded predominantly via dichloroelimination to vinyl chloride (VC). Ultimately, chloroethanes were converted to chloroethenes (mainly VC and DCEs) which persisted in the microcosms for very long periods along with PCE and TCE originally present in the groundwater. Hydrogenolysis of chloroethenes occurred only after highly reducing methanogenic conditions were established. However, substantial conversion to ethene (ETH) was observed only in microcosms amended with yeast extract (200 mg/l), suggesting that groundwater lacked some nutritional factors which were likely provided to dechlorinating microorganisms by this complex organic substrate. Bioaugmentation with an H2-utilizing PCE-dechlorinating Dehalococcoides spp. -containing culture resulted in the conversion of 1,1,2,2-TeCA, PCE and TCE to ETH and VC. No chloroethanes accumulated during degradation suggesting that 1,1,2,2-TeCA was degraded through initial dichloroelimination into DCEs and then typical hydrogenolysis into ETH and VC.
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  • 2
    ISSN: 1572-9729
    Keywords: Delftia acidovorans MC1 ; 2,4-dichlorophenoxyacetic acid (2,4-D) ; 2-(2,4-dichlorophenoxy) propanoic acid (2,4-DP) ; effect of tfdK gene ; simultaneous utilization of 2,4-D and 2,4-DP ; uptake characteristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Growth of Delftia acidovorans MC1 on 2,4-dichlorophenoxyacetic acid (2,4-D) and on racemic 2-(2,4-dichlorophenoxy)propanoic acid ((RS)-2,4-DP) was studied in the perspective of an extension of the strain’s degradation capacity at alkaline pH. At pH 6.8 the strain grew on 2,4-D at a maximum rate (μmax) of 0.158 h−1. The half-maximum rate-associated substrate concentration (Ks) was 45 μM. At pH 8.5 μmax was only 0.05 h−1 and the substrate affinity was mucher lower than at pH 6.8. The initial attack of 2,4-D was not the limiting step at pH 8.5 as was seen from high dioxygenase activity in cells grown at this pH. High stationary 2,4-D concentrations and the fact that μmax with dichlorprop was around 0.2 h−1 at both pHs rather pointed at limited 2,4-D uptake at pH 8.5. Introduction of tfdK from D. acidovorans P4a by conjugation, coding for a 2,4-D-specific transporter resulted in improved growth on 2,4-D at pH 8.5 with μmax of 0.147 h−1 and Ks of 267 μM. Experiments with labeled substrates showed significantly enhanced 2,4-D uptake by the transconjugant TK62. This is taken as an indication of expression of the tfdK gene and proper function of the transporter. The uncoupler carbonylcyanide m-chlorophenylhydrazone (CCCP) reduced the influx of 2,4-D. At a concentration of 195 μM 2,4-D, the effect amounted to 90% and 50%, respectively, with TK62 and MC1. Cloning of tfdK also improved the utilization of 2,4-D in the presence of (RS)−2,4-DP. Simultaneous and almost complete degradation of both compounds occurred in TK62 up to D = 0.23 h−1 at pH 6.8 and up to D = 0.2 h−1 at pH 8.5. In contrast, MC1 left 2,4-D largely unutilized even at low dilution rates when growing on herbicide mixtures at pH 8.5.
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  • 3
    ISSN: 1572-9729
    Keywords: bioremediation ; composting ; ecotoxicity ; oil sludge
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The present work attempts to ascertain the efficacy of low cost technology (in our case, composting) as a bioremediation technique for reducing the hydrocarbon content of oil refinery sludge with a large total hydrocarbon content (250–300 g kg−1), in semiarid conditions. The oil sludge was produced in a refinery sited in SE Spain The composting system designed, which involved open air piles turned periodically over a period of 3 months, proved to be inexpensive and reliable. The influence on hydrocarbon biodegradation of adding a bulking agent (wood shavings) and inoculation of the composting piles with pig slurry (a liquid organic fertiliser which adds nutrients and microbial biomass to the pile) was also studied. The most difficult part during the composting process was maintaining a suitable level of humidity in the piles. The most effective treatment was the one in which the bulking agent was added, where the initial hydrocarbon content was reduced by 60% in 3 months, compared with the 32% reduction achieved without the bulking agent. The introduction of the organic fertiliser did not significantly improve the degree of hydrocarbon degradation (56% hydrocarbon degraded). The composting process undoubtedly led to the biodegradation of toxic compounds, as was demonstrated by ecotoxicity tests using luminescent bacteria and tests on plants in Petri dishes.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1572-9729
    Keywords: bioremediation ; heavy metals ; metal availability ; organic matter ; pyrite ; sulphide oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A field experiment, lasting 14 months, was carried out in order to assess the effect of organic amendment and lime addition on the bioavailability of heavy metals in contaminated soils. The experiment took place in a soil affected by acid, highly toxic pyritic waste from the Aznalcóllar mine (Seville, Spain) in April 1998. The following treatments were applied (3 plots per treatment): cow manure, a mature compost, lime (to plots having pH 〈 4), and control without amendment. During the study two crops of Brassica juncea were grown, with two additions of each organic amendment. Throughout the study, the evolution of soil pH, total and available (DTPA-extractable) heavy metals content (Zn, Cu, Mn, Fe, Pb and Cd), electrical conductivity (EC), soluble sulphates and plant growth and heavy metal uptake were followed. The study indicates that: (1) soil acidification, due to the oxidation of metallic sulphides in the soil, increased heavy metal bioavailability; (2) liming succeeded in controlling the soil acidification; and (3) the organic materials generally promoted fixation of heavy metals in non-available soil fractions, with Cu bioavailability being particularly affected by the organic treatments.
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  • 5
    ISSN: 1572-8838
    Keywords: 2,4-dichlorophenoxyacetic acid (2,4-D) ; Fenton's reagent ; hydrogen peroxide ; hydroxyl radical ; total organic carbon (TOC) ; water treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The electrochemical production of Fenton's reagent by simultaneous reduction of dioxygen and ferric ions on a carbon felt electrode, permits a controlled, in situ generation of hydroxyl (OH·) radicals. The possibility of using electrochemically produced OH⋅ radicals for solving environmental problems is investigated. Continuous and controlled production of hydroxyl radicals was achieved by electrochemical reduction of O2 in the presence of a catalytic amount of ferric or ferrous ion. These radicals are used for remediation of water containing toxic-persistent-bioaccumulative organic pollutants through their transformation into biodegradable compounds or through their mineralization into H2O and CO2. A widely used herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D), was selected as a model for a toxic organic pollutant. High pressure liquid chromatography (HPLC) was used to quantify the distribution of the hydroxylated products obtained. Rate constants for the hydroxylation reactions of 2,4-D, 2,4-dichlorophenol (2,4-DCP), 2,4-dichlororesorcinol (2,4-DCR) and 4,6-dichlororesorcinol (4,6-DCR) were determined. The mineralization of 2,4-D and its derivatives was followed by total organic carbon (TOC) measurements. More than 95% of 2,4-D and the intermediates generated during the electrolysis can be mineralized.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Geotechnical and geological engineering 18 (2000), S. 313-334 
    ISSN: 1573-1529
    Keywords: bioremediation ; carbon substrate ; 1,2-dichloroethane ; methanol ; molasses ; soil columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Historic spillages of chlorinated hydrocarbons at a vinyl chloride plant in the Rotterdam–Botlek area in The Netherlands has lead to deep-seated pollution of the underlying aquifer. The principal pollutant is 1,2-dichloroethane (1,2-DCA). As a temporary measure, the contamination is being contained using a pump and treat system. In the long term, in-situ bioremediation has been proposed using a biologically active zone where pollutants would be dechlorinated by microorganisms that simultaneously degrade other carbon sources. In order to investigate the suitability of this new technology, a programme of laboratory tests was carried out. The laboratory programme involved a series of anaerobic soil column tests, where the selection and delivery of different carbon substrates that stimulated 1,2-DCA dechlorination were investigated. The soil columns were prepared using soil and groundwater samples from boreholes. Groundwater was flushed through the columns under anaerobic conditions. A comparison was made between the transformation of 1,2-DCA without a carbon substrate and in the presence of sugars (molasses) and alcohol (methanol) respectively. In addition, different modes of delivery were investigated. In the case of molasses, the material was injected into the column as a plug to simulate grout injection in the field, whereas methanol was delivered as a constant flow dissolved in the influent. Both carbon substrates resulted in the biotransformation of 1,2-DCA. However, fermentation of molasses produced secondary effects that led to a drop in pH and an excessive production of carbon dioxide, which temporarily blocked the flow of groundwater.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Bioscience reports 20 (2000), S. 239-258 
    ISSN: 1573-4935
    Keywords: heavy metals ; phytoremediation ; bioremediation ; bioavailability ; chemical availability ; soil microorganisms ; plant-microbe interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In this review, chemical and biological parameters are discussed thatstrongly influence the speciation of heavy metals, their availability tobiological systems and, consequently, the possibilities to usebioremediation as a cleanup tool for heavy metal polluted sites. In orderto assess heavy metal availability, a need exists for rapid, cost-effectivesystems that reliably predict this parameter and, based on this, thefeasibility of using biological remediation techniques for site managementand restoration. Special attention is paid to phytoremediation as anemerging technology for stabilization and remediation of heavy metalpollution. In order to improve phytoremediation of heavy metal pollutedsites, several important points relevant to the process have to beelucidated. These include the speciation and bioavailability of the heavymetals in the soil determined by many chemical and biological parameters,the role of plant-associated soil microorganisms and fungi inphytoremediation, and the plants. Several options are described how plant-associated soil microorganisms canbe used to improve heavy metal phytoremediation.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Hydrogeology journal 8 (2000), S. 126-141 
    ISSN: 1435-0157
    Keywords: Key words microbial processes ; contamination ; bioremediation ; lipid analysis ; phospholipid fatty acids (PLFA)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Résumé Ce papier passe en revue les applications des techniques biochimiques basées sur les lipides pour caractériser les communautés microbiennes présentes dans les aquifères et dans les autres habitats souterrains profonds. Ces techniques, telles que l'analyse des acides gras phospholipidiques (PLFA), peuvent fournir des informations sur un ensemble de caractères microbiens, tels que la biomasse, la physiologie, l'identité taxonomique et fonctionnelle, et surtout la composition de la communauté. En outre, l'analyse statistique multivariée des données sur les lipides peut établir les liens entre des changements spatiaux ou temporels dans la communauté microbienne et des facteurs environnementaux. L'utilisation des techniques basées sur les lipides dans l'étude de la microbiologie des eaux souterraines est intéressante parce qu'elle ne nécessite pas de mise en culture et qu'elle peut fournir des données quantitatives sur les communautés dans leur ensemble. Toutefois, les effets combinés de changements physiologiques et phylogénétiques sur la composition d'une communauté peuvent brouiller l'interprétation des données; de nombreuses questions se posent sur la validité des différentes techniques lipidiques. Malgré ces oppositions, la recherche basée sur les lipides a commencéà montrer des tendances dans la composition des communautés dans les aquifères pollués et dans ceux non perturbés; ces résultats contribuent ainsi à notre compréhension de l'écologie microbienne des eaux souterraines et montrent qu'il existe un potentiel pour leur utilisation en vue d'une optimisation de la dépollution biologique des eaux souterraines.
    Abstract: Resumen Se revisan distintas técnicas bioquímicas que se basan en el análisis de lípidos para caracterizar las comunidades microbianas en hábitats subsuperficiales, incluyendo acuíferos. Estas técnicas, entre las que se incluye el análisis de ácidos grasos fosfolípidos (PLFA), pueden proporcionar información sobre toda una serie de características de las comunidades microbianas, como su biomasa, fisiología, identidad taxonómica y funcional y composición. Además, el análisis estadístico multivariado de los datos de lípidos permite relacionar los cambios espaciales o temporales en las comunidades microbianas con factores ambientales. Las técnicas basadas en lípidos son muy útiles para el estudio microbiológico de las aguas subterráneas, puesto que no requieren cultivos y además proporcionan datos cuantitativos de comunidades completas. Sin embargo, la acción combinada de los cambios fisiológicos y filogenéticos en la composición de lípidos en una comunidad pueden confundir la interpretación de los datos, por lo existen muchas cuestiones abiertas respecto a la validez de algunas de estas técnicas. A pesar de estas dificultades, estas técnicas han permitido detectar diferentes tendencias en la composición de las comunidades en acuíferos con y sin contaminación, lo que contribuye a nuestro entendimiento de la ecología microbiana de los acuíferos. Este último aspecto tiene un uso potencial en la optimización de los métodos de biorremediación de acuíferos.
    Notes: Abstract  This paper reviews published applications of lipid-based biochemical techniques for characterizing microbial communities in aquifers and other deep subsurface habitats. These techniques, such as phospholipid fatty acid (PLFA) analysis, can provide information on a variety of microbial characteristics, such as biomass, physiology, taxonomic and functional identity, and overall community composition. In addition, multivariate statistical analysis of lipid data can relate spatial or temporal changes in microbial communities to environmental factors. The use of lipid-based techniques in the study of groundwater microbiology is advantageous because they do not require culturing and can provide quantitative data on entire communities. However, combined effects of physiological and phylogenetic changes on the lipid composition of a community can confound interpretation of the data, and many questions remain about the validity of various lipid techniques. Despite these caveats, lipid-based research has begun to show trends in community composition in contaminated and pristine aquifers that contribute to our understanding of groundwater microbial ecology and have potential for use in optimization of bioremediation of groundwater pollutants.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Hydrogeology journal 8 (2000), S. 77-88 
    ISSN: 1435-0157
    Keywords: microbial processes ; contamination ; metals ; hydrocarbons ; bioremediation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Geobacter se convierten en los miembros dominantes de la comunidad microbiana cuando se desarrollan condiciones Fe(III)-reductoras, bien como resultado de la contaminación orgánica, bien por estimulación artificial. En consecuencia, se hace necesario un mayor entendimiento de la ecofisiologéa de los microorganismos del género Geobacter para mejorar las predicciones sobre atenuación natural de los contaminantes orgánicos bajo condiciones anaerobias y para el diseño de estrategias de biorremediación del subsuelo en los casos de contaminación por metales.
    Notes: Geobacter become dominant members of the microbial community when Fe(III)-reducing conditions develop as the result of organic contamination, or when Fe(III) reduction is artificially stimulated. These results suggest that further understanding of the ecophysiology of Geobacter species would aid in better prediction of the natural attenuation of organic contaminants under anaerobic conditions and in the design of strategies for the bioremediation of subsurface metal contamination.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Hydrogeology journal 8 (2000), S. 63-76 
    ISSN: 1435-0157
    Keywords: microbial processes ; contamination ; bioremediation ; natural attenuation ; heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Type of Medium: Electronic Resource
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  • 11
    ISSN: 1572-9729
    Keywords: bioremediation ; hydrocarbon-degrading bacteria ; indigenous microflora ; oil ; Rhodococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper summarises the experience accumulated duringthe field application of biopreparation `Rhoder' (solely or in a combinationwith preliminary mechanical collection of free oil) for remediation of oil polluted aquatic systems and soils in the Moscow region and Western Siberia during 1994–1999.It was demonstrated that `Rhoder' had a very high efficiency (〉99%) for bioremediation of the open aquatic surfaces (100 m2 bay of the River Chernaya, two 5,000 m2 lakes in Vyngayakha) at initial level of oil pollution of 0.4–19.1 g/l. During remediation of the wetland (2,000 m2) in Urai (initial level of oil pollution of 10.5 g/l), a preliminary mechanical collection of oil was applied (75% removal) followed by a triple treatment with `Rhoder'. It resulted in an overall treatment efficiency of 94%. Relatively inferior results of bioremediation of the 10,000 m2 wetland in Vyngayakha (65% removal) and the 1,000 m2 marshy peat soil in Nizhnevartovsk (19% removal) can be attributed to the very high initial level of oil pollution (24.3 g/l and 〉750 g/g dry matter, respectively) aggravated by the fact that it was impossible to apply a preliminary mechanical collection of oil on these sites. A possible strategy for remediation of such heavily polluted sitesis discussed.
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  • 12
    ISSN: 1572-9729
    Keywords: aerobic degradation ; bioaugmentation ; bioreactors ; bioremediation ; MTBE ; natural attenuation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The addition of methyl tert-butyl ether (MTBE) to gasoline has resulted in public uncertainty regarding the continued reliance on biological processes for gasoline remediation. Despite this concern, researchers have shown that MTBE can be effectively degraded in the laboratory under aerobic conditions using pure and mixed cultures with half-lives ranging from 0.04 to 29 days. Ex-situ aerobic fixed-film and aerobic suspended growth bioreactor studies have demonstrated decreases in MTBE concentrations of 83% and 96% with hydraulic residence times of 0.3 hrs and 3 days, respectively. In microcosm and field studies, aerobic biodegradation half-lives range from 2 to 693 days. These half-lives have been shown to decrease with increasing dissolved oxygen concentrations and, in some cases, with the addition of exogenous MTBE-degraders. MTBE concentrations have also been observed to decrease under anaerobic conditions; however, these rates are not as well defined. Several detailed field case studies describing the use of ex-situ reactors, natural attenuation, and bioaugmentation are presented in this paper and demonstrate the potential for successful remediation of MTBE-contaminated aquifers. In conclusion, a substantial amount of literature is available which demonstratesthat the in-situ biodegradation of MTBE is contingent on achieving aerobic conditions in the contaminated aquifer.
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Biodegradation 11 (2000), S. 107-116 
    ISSN: 1572-9729
    Keywords: bioremediation ; Fe(III) reduction ; methanogenesis ; subsurfce microbiology ; sulfate reduciton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Although many studies have indicated that benzene persists under anaerobic conditions in petroleum-contaminated environments, it has recently been documented that benzene can be anaerobically oxidized with most commonlyconsidered electron acceptors for anaerobic respiration. These include: Fe(III),sulfate, nitrate, and possibly humic substances. Benzene can also be convertedto methane and carbon dioxide under methanogenic conditions. There is evidencethat benzene can be degraded under in situ conditions in petroleum-contaminatedaquifers in which either Fe(III) reduction or methane production is the predominant terminal electron-accepting process. Furthermore, evidence from laboratory studies suggests that benzene may be anaerobically degraded in petroleum-contaminated marine sediments under sulfate-reducing conditions. Laboratory studies have suggested that within the Fe(III) reduction zone of petroleum-contaminated aquifers, benzene degradation can be stimulated with the addition of synthetic chelators which make Fe(III) more available for microbial reduction. The addition of humic substances and other compounds that contain quinone moieties can also stimulate anaerobic benzene degradation in laboratory incubations of Fe(III)-reducing aquifer sediments by providing an electron shuttle between Fe(III)-reducing microorganisms and insoluble Fe(III) oxides. Anaerobic benzene degradation in aquifer sediments can be stimulated with the addition of sulfate, but in some instances an inoculum of benzene-oxidizing,sulfate-reducing microorganisms must also be added. In a field trial, sulfate addition to the methanogenic zone of a petroleum-contaminated aquifer stimulated the growth and activity of sulfate-reducing microorganisms and enhanced benzene removal. Molecular phylogenetic studies have provided indications of what microorganisms might be involved in anaerobic benzene degradation in aquifers. The major factor limiting further understanding of anaerobic benzene degradation is the lack of a pure culture of an organism capable of anaerobic benzene degradation.
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  • 14
    ISSN: 1572-9729
    Keywords: aerobic ; bioremediation ; biodegradation ; gasoline ; MTBE ; TBA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract With the current practice of amending gasoline with up to 15% by volume MTBE, the contamination of groundwater by MTBE has become widespread. As a result, the bioremediation of MTBE-impacted aquifers has become an active area of research. A review of the current literature on the aerobic biodegradation of MTBE reveals that a number of cultures from diverse environments can either partially degrade or completely mineralize MTBE. MTBE is either utilized as a sole carbon and energy source or is degraded cometabolically by cultures grown on alkanes. Reported degradation rates range from 0.3 to 50 mg MTBE/g cells/h while growth rates (0.01–0.05 g MTBE/g cells/d) and cellular yields (0.1–0.2 g cells/g MTBE) are generally low. Studies on the mechanisms of MTBE degradation indicate that a monooxygenase enzyme cleaves the ether bond yielding tert-butyl alcohol (TBA) and formaldehyde as the dominant detectable intermediates. TBA is further degraded to 2-methyl-2-hydroxy-1-propanol, 2-hydroxyisobutyric acid, 2-propanol, acetone, hydroxyacteone and eventually, carbon dioxide. The majority of these intermediates are also common to mammalian MTBE metabolism. Laboratory studies on the degradation of MTBE in the presence of gasoline aromatics reveal that while degradation rates of other gasoline components are generally not inhibited by MTBE, MTBE degradation could be inhibited in the presence of more easily biodegradable compounds. Controlled field studies are clearly needed to elucidate MTBE degradation potential in co-contaminant plumes. Based on the reviewed studies, it is likely that a bioremediation strategy involving direct metabolism, cometabolism, bioaugmentation, or some combination thereof, could be applied as a feasible and cost-effective treatment method for MTBE contamination.
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  • 15
    ISSN: 1573-6776
    Keywords: bioremediation ; degradation ; hydrocarbon ; oil ; respirometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Oil biodegradation in oil-contaminated sand was simultaneously measured by respirometric and thin-layer chromatography/flame ionization detector (TLC/FID) methods. Degradation rate of 10–32 mg-C kg sand−1 day was achieved by amending the sand with inorganic nutrients and an oil-degrading yeast. The amendment also increased the initial CO2 production rate by 5–15 folds, which was not detected by the TLC/FID analysis. However, it was possible to monitor the accumulation of resin/asphaltene fraction up to 130% by the TLC/FID analysis during the oil degradation.
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  • 16
    ISSN: 1573-6776
    Keywords: bioremediation ; Kuwaiti soil ; polycyclic aromatic hydrocarbon (PAH)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In the uncontaminated farm soil, more than 80% of the supplemented acenaphthene, fluoranthene, and pyrene (100 mg/100 g soil) decreased in 90 days, while ratio of removal was about 20%, 30%, and 0%, respectively, in the Kuwaiti oil-contaminated soil. Simultaneous addition of naphthalene, phenanthrene, and anthrathene (100 mg of each compound/100 g soil) led the acenaphthene to a decrease of about 20% to 45% but not of fluoranthene and pyrene. Addition of the farm soil to the Kuwaiti soil did not enhance the decrease of these three PAHs.
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Biotechnology letters 22 (2000), S. 783-788 
    ISSN: 1573-6776
    Keywords: bioremediation ; mercuric chloride ; Pseudomonas putida
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A mercury removal-recovery system was developed for collection of elemental mercury volatilized by biological mercuric ion reduction. Using the mercury removal-recovery system, removal of mercuric chloride from mercury-containing buffer without nutrients by resting cells of mercury-resistant bacterium, Pseudomonas putida PpY101/pSR134 was tested. Optimum temperature, pH, thiol compounds and cell concentration on removal of mercuric chloride were determined, and 92 to 98% of 40 mg Hg l−1 was recovered in 24 h. The efficiency of mercuric chloride removal from river water and seawater was as high as that observed when using a buffered solution.
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  • 18
    Electronic Resource
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    Springer
    Biotechnology letters 22 (2000), S. 1757-1760 
    ISSN: 1573-6776
    Keywords: bioremediation ; extracellular polymeric substances ; lead ; manganese
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Extracellular polymeric substances (EPS) produced from a strain of Rhizobium etli demonstrated an ability to bind a variety of metals. Cells and capsular EPS rapidly bound Mn2+ ions preferentially to Pb2+ and Cu2+, but also showed an affinity for Pb2+. The binding capabilities of soluble EPS were affected by its extraction and processing. The results suggest potential applications in the field of bioremediation.
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Biotechnology letters 22 (2000), S. 915-919 
    ISSN: 1573-6776
    Keywords: bioremediation ; chlorophenols ; microcosm ; oxygen ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A chlorophenol-contaminated soil was tested for the biodegradability in a semi-pilot scale microcosm using indigenous microorganisms. More than 90% of 4-chlorophenol and 2,4,6-trichlorophenol, initially at 30 mg kg−1, were removed within 60 days and 30 mg pentachlorophenol kg−1 was completely degraded within 140 days. The chlorophenols were degraded more effectively under aerobic condition than under anaerobic condition. Soil moisture had a significant effect with the slowest degradation rate of chlorophenols at 25% in the range of 10–40% moisture content. At 25–40%, the rate of chlorophenol degradation was directly related to the soil moisture content, whereas at 10–25%, it was inversely related. Limited oxygen availability through soil agglomeration at 25% moisture content might decrease the degradation rate of chlorophenols.
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  • 20
    ISSN: 1573-6776
    Keywords: bioremediation ; genetic engineering ; heavy metal ; hydrogen sulfide ; thiosulfate reductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The thiosulfate reductase gene (phsABC) from Salmonella typhimuriumwas expressed in Escherichia coliin order to produce sulfide from inorganic thiosulfate and precipitate metals as metal sulfide complexes. The sulfide-engineered strain removed significant amounts of heavy metals from the medium within 24 h: 99% of zinc up to 500 μM, 99% of lead up to 200 μM, 99% of 100 μM and 91% of 200 μM cadmium. In a mixture of 100 μM each of cadmium, lead, and zinc, the strain removed 99% of the total metals from solution within 10 h. Cadmium was removed first, lead second, and zinc last. These results have important implications for removal of metals from wastewater contaminated with several metals.
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  • 21
    ISSN: 1573-2932
    Keywords: bioremediation ; microbial degradation ; microorganisms ; pesticide contamination ; phytoremediation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The fate of atrazine and metolachlor,applied as a mixture, in soil taken from twopesticide-contaminated sites in Iowa (denoted as Alphaor Bravo) were determined in laboratory studies. Atrazine and metolachlor degradation, as well asatrazine mineralization, were greater in soilcollected from Kochia scoparia L. (Schrader)rhizosphere than in soils from unvegetated areas. Theradiolabeled 14C-carbinol and14C-morpholinone metabolites were identified in14C-metolachlor-applied soil 60 d aftertreatment. The half-life for atrazine in Alpha soilwas significantly less in the rhizosphere soil (50 d)than in unvegetated soil (193 d). Quantities ofspecific atrazine degraders were one to two orders ofmagnitude greater in Bravo soils than in Alpha soils. In an experiment with plants present, significantlymore 14C-atrazine was taken up by K.scoparia (9.9% of the applied 14C) than by Brassica napus L. Significantly less atrazine wasextractable from soils vegetated with K.scoparia than from soils vegetated with B.napus or unvegetated soils.
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  • 22
    ISSN: 1573-2932
    Keywords: bioassays ; bioremediation ; microbiology ; soil contamination ; soil toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A soil contaminated with polycyclic aromatic hydrocarbons, petroleum hydrocarbons and chlorophenols was bioremediated in field box plots. Three different bioremediation treatments (tillage and irrigation alone (box plot 2) or in addition to amendment with nitrogen and phosphorus (box plots 3 and 4) and additional organic amendment composed ofagricultural crop residues (box plot 4)) were comparedusing chemical analysis for target contaminants andsix toxicity tests (seed germination, earthwormsurvival, SOS Chromotest, Toxi-Chromotest, solid-phaseMicrotox® andred blood cell (RBC) haemolysisassay). Degradation was enhanced, and toxicity wasgenerally the most reduced, in box plots 3 and 4. Although chemical analysis indicated that the twoamendment protocols were equally effective, soiltoxicity was generally the most reduced in box plot 4. The earthworm survival and seed germination assayswere the most reliable and relevant toxicity tests. Difficulties arising with the other tests includedinsensitivity to changes in soil contaminant levels,inconsistency and interference by soil particles andother soil constituents. Because of the lack ofagreement between toxicity tests, these resultssupport the use of a battery of toxicity tests inconjunction with chemical analysis, when assessing theefficacy of bioremediation.
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  • 23
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    Water, air & soil pollution 120 (2000), S. 315-329 
    ISSN: 1573-2932
    Keywords: biodegradation kinetics ; bioremediation ; BTX ; factorsaffecting bioremediation ; groundwater velocity ; Monod kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The effect of groundwater velocity onbioremediation of gasoline contaminated sandy soil hasbeen investigated using a pilot scale sand tank model.The effect of hydrogen peroxide and contaminantconcentration are also included. A factorialexperiment has been conducted to study three factors,groundwater velocity, inlet BTX concentration andhydrogen peroxide dose. Observed concentration datacollected from the sand tank model have been used forestimating the transport parameters. Three differentbiodegrdation kinetics, namely first-order/zero-order,Monod and Michaelis Menten (a modification of Monodkinetics considering no microbial growth) kineticshave been used to model the biodegration. The datahave been found to fit all three models withacceptable coefficient of regression. Groundwatervelocity has been found to be the most significantfactor governing the biodegradation rate constants(determined from the first-order rate constant) of BTXcompounds. Hydrogen peroxide dose and BTX concentration have also been found to be significant factors.
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  • 24
    ISSN: 1573-0972
    Keywords: Bacterial community ; bioremediation ; PCR-SSCP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The extent of shift in soil bacterial community structure during bioremediational treatments was investigated by PCR-single-strand-conformation polymorphism (SSCP) analysis, which was followed by computer-assisted cluster analysis of the community fingerprints. While biostimulation as well as bioaugmentation enhanced the degradation of phenanthrene in soil, both bioremediational treatments caused shifts in the bacterial community structure. Drastic changes were observed in the initial phase of bioaugmentation. Our results demonstrate that computer-assisted fingerprint analysis is readily applicable to the study for the comparative analysis of microbial community structure using molecular profiling techniques.
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  • 25
    ISSN: 1572-977X
    Keywords: bioremediation ; mangroves ; microbial degradation ; oil spills
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As part of a larger study on the bioremediation of oil spills in tropical mangrove habitats, we conducted a series of flask experiments to test for the presence of hydrocarbon degrading micro‐organisms in representative wetland habitats. Also tested was the biodegradation of selected oils (Gippsland Crude, Arabian Light Crude and Bunker C), that are transported along the Australian coast. We also tested for potential inhibition of biodegradation by natural organics in the mangrove pore waters and evaluated the ability of an oxygen release compound (ORC) to stimulate biodegradative processes. Evaporation was a significant factor in removing the light alkane and aromatic hydrocarbons from air and nitrogen sparged flasks. Evaporation removed ∼27% of the Gippsland, ∼37%of the Arabian, and ∼10% of the Bunker oils. Oxygen was necessary to support biodegradation as expected. The micro‐organisms were capable of biodegrading the non‐volatile saturate fraction of each oil. Degradation removed another 14 of the Gippsland, 30 of the Arabian, and 22 of the Bunker C oils. Normalisation of the individual aromatic hydrocarbon classes to internal triterpane biomarkers indicated some degradation of aromatics in the Arabian Light and Bunker C oils. Although alkane degradation rates were comparable in the three oils, the Gippsland oil had a higher wax content and after 14 days incubation, still contained as much as 25 of the alkanes present in the original oil. Thus, degradation of its aromatic fraction may have been delayed. Based on these results we estimate that Arabian Light Crude oil would have a shorter residence time than the other oils in mangrove sediment. It has a higher content of light hydrocarbons, which are readily removed by both physical and microbial processes. The Bunker C would be expected to have the longest residence time in mangrove sediment, because it contains a larger percentage of higher molecular weight, unresolved components. Comparison of the efficiency of inoculates from three tropical intertidal habitats (Avicennia and Rhizophora mangroves, plus salt marsh sediments) indicated the presence of hydrocarbon degrading micro‐organisms in all three habitats. There was no known history of oil contamination in the soil source area. There was no inhibition of degradation due to addition of mangrove pore waters. The ORC did not facilitate degradation in closed laboratory experiments. These results were used to formulate a bioremediation strategy to treat oiled sediments in mangrove forests in Queensland Australia, which was based on forced aeration and nutrient addition. Evaporation was a significant factor in removing the light alkane and aromatic hydrocarbons from air and nitrogen sparged flasks. Evaporation removed ∼27% of the Gippsland, ∼37% of the Arabian, and ∼10% of the Bunker oils. Oxygen was necessary to support biodegradation as expected. The micro-organisms were capable of biodegrading the non-volatile saturate fraction of each oil. Degradation removed another 14% of the Gippsland, 30% of the Arabian, and 22% of the Bunker C oils. Normalisation of the individual aromatic hydrocarbon classes to internal triterpane biomarkers indicated some degradation of aromatics in the Arabian Light and Bunker C oils. Although alkane degradation rates were comparable in the three oils, the Gippsland oil had a higher wax content and after 14 days incubation, still contained as much as 25% of the alkanes present in the original oil. Thus, degradation of its aromatic fraction may have been delayed. Based on these results we estimate that Arabian Light Crude oil would have a shorter residence time than the other oils in mangrove sediment. It has a higher content of light hydrocarbons, which are readily removed by both physical and microbial processes. The Bunker C would be expected to have the longest residence time in mangrove sediment, because it contains a larger percentage of higher molecular weight, unresolved components. Comparison of the efficiency of inoculates from three tropical intertidal habitats (Avicennia and Rhizophora mangroves, plus salt marsh sediments) indicated the presence of hydrocarbon degrading micro-organisms in all three habitats. There was no known history of oil contamination in the soil source area. There was no inhibition of degradation due to addition of mangrove pore waters. The ORC did not facilitate degradation in closed laboratory experiments. These results were used to formulate a bioremediation strategy to treat oiled sediments in mangrove forests in Queensland Australia, which was based on forced aeration and nutrient addition.
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  • 26
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    Journal of thermal analysis and calorimetry 57 (1999), S. 303-312 
    ISSN: 1572-8943
    Keywords: bioremediation ; calorimetry ; hydrocarbons biodegradation ; microbial growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The calorimetric cells of a Setaram BT 2.15 flux calorimeter have been modified, in order to measure the heat production associated with microbial growth, with a continuous flow of gas and liquid through the sample. Good conditions for the growth of the microorganisms present in a polluted soil were determined and the possibility of the bioremediation examined. It was shown that the biodegradation of hydrocarbons adsorbed for a long time in the soil is a very slow process difficult to study with calorimetry. On the contrary, sodium succinate and different C14 hydrocarbons were easily biodegradated, producing a large quantity of heat.
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  • 27
    ISSN: 1573-5176
    Keywords: bioremediation ; integrated aquaculture ; nori ; phenology ; Porphyra ; salmon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract For rapid growth and appropriate pigmentation,Porphyra requires the constant availability of nutrients, especially in summer when temperate waters are generally nutrient depleted. Cultivation near salmon cages allows the alleviation of this seasonal depletion by using the significant loading of fishf arms, which is then valued (wastes become fertilisers) and managed (competition for nutrients between desirable algal crops and problem species associated with severe disturbances). Porphyra,being an extremely efficient nutrient pump, is an excellent candidate for integrated aquaculture for bioremediation and economic diversification. Frequent harvesting provides for constant removal of significant quantities of nutrients from coastal waters, and for production of seaweeds of commercial value. The production of P. yezoensis being limited in the Gulf of Maine, an assessment of the potential of seven native north-west Atlantic Porphyra species is presently in progress. To enable the production of conchospores for net seeding, the phenology of these species and the conditions for their vegetative conchocelis exponential growth, conchosporangium induction, and conchospore maturation were determined. The development of integrated aquaculture systems is a positive initiative for optimising the efficiency of aquaculture operations, while maintaining the health of coastal waters.
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  • 28
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    Biotechnology techniques 13 (1999), S. 859-863 
    ISSN: 1573-6784
    Keywords: bioremediation ; hydrocarbons ; lipase ; oil ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The evaluation of soil lipase activity as a tool to monitor the decontamination of a freshly oil-polluted soil was tested in a laboratory study. An arable soil was experimentally contaminated with diesel oil at 5 mg hydrocarbons g−1 soil dry weight and incubated with and without fertilization (N-P-K) for 116 days at 20 °C. Lipase activity and counts of oil-degrading microorganisms were measured at regular time intervals, and the correlations with the levels of hydrocarbon concentrations in soil were investigated. The residual soil hydrocarbon concentration correlated significantly negatively with soil lipase activity and with the number of oil-degrading microorganisms, independent of fertilization. The induction of soil lipase activity is a valuable indicator of oil biodegradation in naturally attenuated (unfertilized) and bioremediated (fertilized) soils.
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  • 29
    ISSN: 1572-9729
    Keywords: bioremediation ; fungi ; higher-condensed PAH ; oxidative enzymes ; soil microflora
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Seven commercial 3- to 7-ring (R) polycyclic aromatic hydrocarbons (PAH) as well as PAH derived from lignite tar were spiked into 3 soils (0.8 to 9.7% of organic carbon). The disappearance of the original PAH was determined for the freshly spiked soils, for soils incubated for up to 287 d with their indigenous microflora, and for autoclaved, unsterile and pasteurized soils inoculated with basidiomycetous and ascomycetous fungi. Three to 12 d after spiking, 22 to 38% of the PAH could no longer be recovered from the soils. At 287 d, 88.5 to 92.7%, 83.4 to 87.4%, and 22.0 to 42.1% of the 3-, 4-, and 5- to 7-R PAH, respectively, had disappeared from the unsterile, uninoculated soils. In 2 organic-rich sterile soils, the groups of wood- and straw-degrading, terricolous, and ectomycorrhizal fungi reduced the concentration of 5 PAH by 12.6, 37.9, and 9.4% in 287 d. Five- to 7-R PAH were degraded as efficiently as most of the 3- to 4-R PAH. In organic-rich unsterile soils inoculated with wood- and straw-degrading fungi, the degradation of 3- to 4-R PAH was not accelerated by the presence of fungi.The 5- to 7-R PAH, which were not attacked by bacteria, were degraded by fungi to 29 to 42% in optimum combinations of fungal species and soil type. In organic-poor unsterile soil, these same fungi delayed the net degradation of PAH possibly for 2 reasons. Mycelia of Pleurotus killed most of the indigenous soil bacteria expected to take part in the degradation of PAH, whereas those of Hypholoma and Stropharia promoted the development of opportunistic bacteria in the soil, which must not necessarily be PAH degraders. Contemporarily, the contribution of the fungi themselves to PAH degradation may be negligible in the absence of soil organic matter due to the lower production of ligninolytic enzymes. It is concluded that fungi degrade PAH irrespective of their molecular size in organic-rich and wood chip-amended soils which promote fungal oxidative enzyme production.
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  • 30
    ISSN: 1572-9729
    Keywords: Bioprocessing ; bioremediation ; Chelatobacter heintzii ; nitrilotriacetic acid ; plutonium ; radiotoxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The radiotoxicity of plutonium in NTA-degrading Chelatobacter heintzii cell suspensions was investigated as part of a more general study to establish the key interactions between actinide-organic complexes and microorganisms in the subsurface. The radiation tolerance of C. heintzii, based on 60Co gamma irradiation experiments, was 165 ± 30 Gy. No bacteria survived irradiation doses greater than 500 Gy. In the presence of plutonium, where alpha particle decay was the primary source of ionizing radiation, the observed toxicity was predominantly radiolytic rather than chemical. This was evident by the greater effect of activity, rather than concentration, on the toxicity noted. Bioassociation of plutonium with C. heintzii was postulated to be an important and necessary step in the observed loss of cell viability since this was the best way to account for the observed death rate. The radiotoxicity of plutonium towards bacteria is a potentially important consideration in the bioremediation of sites contaminated with radionuclide-organic mixtures and the bioprocessing of nuclear waste.
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  • 31
    ISSN: 1572-9729
    Keywords: bioremediation ; composting ; petroleum ; soil ; thermophilic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of the C/N ratio, CaCO3 and PO4 addition, and temperature profile on reactor-based composting of weathered hydrocarbon-contaminated soil were evaluated in a series of 30-day tests in temperature-controlled mini-composters. Soil containing 17,000 mg (kg dry soil)−1 mineral oil and grease (MOG) was composted with maple leaves and alfalfa. Although the leaves and alfalfa also contained MOG, degradation of contaminated soil derived MOG (total MOG degradation minus MOG degradation in a control with no soil) increased from 0 to 45% as the quantity of co-substrate increased from 0 to 63%. Simulation of biopile conditions (i.e., aeration and addition of mineral salts but no co-substrate) resulted in only 6% MOG degradation. Addition of CaCO3 before composting increased total MOG degradation from 23% to 43%. Total MOG degradation increased with decreasing C/N ratio. At a molar C/N ratio of 17, 43% of the total MOG was degraded in 30 days, while at a C/N ratio of 40 there was no total MOG degradation. When temperatures ranging from 23 to 60 °C were investigated, 50 °C maintained for 29 days resulted in the maximum degradation which was 68% of total initial MOG.
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  • 32
    ISSN: 1572-9729
    Keywords: bioremediation ; colonization of soil ; polyaromatic hydrocarbons (PAHs) ; white rot fungi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Selected strains of three species of white rot fungi, Pleurotus ostreatus, Phanerochaete chrysosporium and Trametes versicolor, were grown in sterilized soil from straw inocula. The respective colonization rates and mycelium density values decreased in the above mentioned order. Three- and four-ringed PAHs at 50 ppm inhibited growth of fungi in soil to some extent. The activities of fungal MnP and laccase (units per g dry weight of straw or soil), extracted with 50 mM succinate-lactate buffer (pH 4.5), were 5 to 20-fold higher in straw compared to soil. The enzyme activities per g dry soil in P. ostreatus and T. versicolor were similar, in contrast to P. chrysosporium, where they were extremely low. Compared to the aerated controls, P. ostreatus strains reduced the levels of anthracene, pyrene and phenanthrene by 81–87%, 84–93% and 41–64% within 2 months, respectively. During degradation of anthracene, all P. ostreatus strains accumulated anthraquinone. PAH removal rates in P. chrysosporium and T. versicolor soil cultures were much lower.
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  • 33
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    Biodegradation 10 (1999), S. 169-176 
    ISSN: 1572-9729
    Keywords: biodegradation ; biofiltration ; bioremediation ; extremophile ; VOC ; waste gas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A biofilter treating alkylbenzene vapors was characterized for its optimal running conditions and kinetic parame-ters. Kinetics of the continuous biofilter were compared to batch kinetic data obtained with biofilm samples as well as with defined microbial consortia and with pure culture isolates from the biofilter. Both bacteria and fungi were present in the bioreactor. Five strains were isolated. Two bacteria, Bacillus and Pseudomonas, were shown to be dominant, as well as a Trichosporon strain which could, however, hardly grow on alkylbenzenes in pure culture. The remaining two strains were most often overgrown by the other three organisms in liquid phase batch cultures μ max, KS, KI values and biodegradation rates were calculated and compared for the difterent mixed and pure cultures. Since filter bed acidification was observed during biofiltration studies reaching a pH of about 4, experiments were also undertaken to study the influence of pH on performance of the different cultures. Biodegradation and growth were possible in all cases, over the pH range 3.5–7.0 at appreciable rates, both with mixed cultures and with pure bacterial cultures. Under certain conditions, microbial activity was even observed in the presence of alkylbenzenes down to pH 2.5 with mixed cultures, which is quite unusual and explains the ability of the present biocatalyst to remove alkylbenzenes with high efficiency in biofilters under acidic conditions.
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  • 34
    ISSN: 1572-9729
    Keywords: Aeration ; bioremediation ; composting ; glucose ; hexadecane ; microcosm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The need for aeration of microcosms duringmineralization of 14C-labeled compounds in highoxygen demand environments was assessed using activecompost-soil mixtures as the model system. Rapidmineralization of 14C-hexadecane occurred incontinuously aerated microcosms while nomineralization occurred in unaerated microcosms. Dailyflushing with air also yielded no mineralization.Mineralization of 14C-glucose was much lessdependent on aeration. The alkaline solution volumeand number of CO2 traps required for continuousaeration were calculated and tested experimentally.
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  • 35
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    Biotechnology letters 21 (1999), S. 741-745 
    ISSN: 1573-6776
    Keywords: anaerobic microbial consortium ; biodegradation ; bioremediation ; biphenyl ; p-cresol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Biphenyl was readily degraded and mineralized to CO2 and CH4 by a PCB-dechlorinating anaerobic microbial consortium. Degradation occurred when biphenyl was supplied as a sole source of carbon or as a co-metabolic substrate together with glucose and methanol. p-Cresol was detected and confirmed by mass spectroscopy as a transient intermediate. Production of 14 C-CO2 and 14C-CH4 from 14C-biphenyl was observed in the approximate ratio of 1:2. The results indicated the existence of novel pathways for biphenyl degradation in a natural anaerobic microbial community.
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  • 36
    ISSN: 1573-6784
    Keywords: bioremediation ; dehydrogenase ; enumeration ; respiration ; subsurface
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract To assess the biopotential for remediation, microbiological ex situ activities were examined in a subsurface site contaminated in the past with fluctuating hydrocarbon amounts. A novel method for estimating the proportion of hydrocarbon degraders was used. There was not in all cases a correlation between the results of chemical analysis and microbiological activities. However, the level of soil respiration (between 440 and 515 μg CO2/g dry weight h−1) correlated well with hydrocarbon contamination of the subsurface.
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  • 37
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    Environmental monitoring and assessment 58 (1999), S. 243-281 
    ISSN: 1573-2959
    Keywords: bioremediation ; oxygen release compounds ; dispersion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The use of oxygen releasing solids in passive wells has become of considerable interest in the bioremediation of groundwater contaminated with hydrocarbons and other biodegradable contaminants. Labor, operating, and maintenance costs of this technology are quite competitive with more conventional techniques in many instances. Because of the small rates of mass transport by transverse dispersion, however, a pin-stripe pattern of alternating contaminant and oxygen distribution is expected downgradient of a line of wells which is unacceptable if it extends beyond the point of compliance downgradient. A mathematical model is presented which permits determination of the maximum well spacing in an array of wells which will yield effective remediation within a specified distance of a plume of contaminated groundwater passing through the array. Transverse dispersion of both oxygen and the contaminant is assumed, and biodegradation is modeled by means of Monod kinetics. Longitudinal numerical dispersion is minimized by the use of a asymmetrical upwind algorithm for modeling advection. Modeling results are presented showing the dependence of model behavior on input parameters.
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  • 38
    ISSN: 1573-2932
    Keywords: bioassays ; bioremediation ; microbiology ; PCP ; soil ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Five bioassays were used to measure toxicity during bioremediation of a soil contaminated with pentachlorophenol (PCP; 335 ppm), polycyclic aromatic hydrocarbons (PAHs; 1225 ppm) and petroleum hydrocarbons (19 125 ppm). Different bioremediation treatments were tested in soil microcosms including amendment with phosphorus and/or PCP-degrading Pseudomonas sp. UG30, either as free cells or encapsulated in κ-carrageenan. Soil toxicity was monitored using the solid-phase Microtox test, SOS-chromotest, lettuce seed germination, earthworm survival and sheep red blood cell (RBC) haemolysis assays. PCP levels were reduced in all treatments after 210 days. The RBC lysis assay, Microtox test and SOS-chromotest indicated reduced toxicity in most of the microcosms by day 210. Trends depicted by lettuce seed germination and earthworm survival LC50 values varied with each treatment. For example, in soil amended with phosphorus, both the seed germination and earthworm survival LC50 data suggested increased soil toxicity. However, for soil treated with encapsulated Pseudomonas sp. UG30 cells, the earthworm survival LC50 data indicated reduced toxicity while seed germination LC50 values showed little change from values obtained prior to bioremediation. Our results show that toxicity trends in a contaminated soil during bioremediation differ according to the assay used.
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  • 39
    ISSN: 1572-9729
    Keywords: bioremediation ; bioslurry reactor ; explosive ; microcosm ; mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Microcosm tests simulating bioslurry reactors with 40% soilcontent, containing high concentrations of TNT and/or RDX,and spiked with either [14C]-TNT or[14C]-RDX were conducted to investigate the fate ofexplosives and their metabolites in bioslurry treatment processes.RDX is recalcitrant to indigenous microorganisms in soil andactivated sludge under aerobic conditions. However, soilindigenous microorganisms alonewere able to mineralize 15% of RDX to CO2 underanaerobic condition, and supplementation of municipal anaerobicsludge as an exogenous source of microorganismssignificantly enhanced the RDX mineralization to 60%. RDXmineralizing activity of microorganisms in soil and sludge wassignificantly inhibited by the presence of TNT. TNTmineralization was poor (〈 2%) and was not markedlyimproved by the supplement ofaerobic or anaerobic sludge. Partitioning studies of[14C]-TNT in the microcosmsrevealed that the removal of TNTduring the bioslurry process was due mainly to thetransformation of TNT and irreversiblebinding of TNT metabolites onto soil matrix. In the case ofRDX under anaerobic conditions,a significant portion (35%) of original radioactivity wasalso incorporated into the biomass andbound to the soil matrix.
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  • 40
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    Transport in porous media 31 (1998), S. 67-88 
    ISSN: 1573-1634
    Keywords: bioremediation ; mixed-hybrid finite elements ; finitevolumes ; flow and transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Technology
    Notes: Abstract This paper presents a numerical solution approach for an existing model for simulating transport and biodegradation in saturated porous media. The discrete approximation makes use of an appropriate blending of mixed-hybrid finite-element and shock-capturing finite-volume schemes. The model is applied for simulating enhanced-bioremediation of highly heterogeneous porous media contaminated by organic pollutants. Injection of water enriched in dissolved oxygen (DO) is considered for accelerating contaminant degradation and concentration of both organic pollutant (substrate) and DO. Heterogeneity is found to produce pools of contaminants which strongly affect DO delivery and, then, the degradation of the organic contaminant. A set of numerical results on representative situations illustrates the effectiveness and the robustness of the present approach. The computational efficiency of the present approach is also estimated in terms of CPU costs and memory requirements.
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  • 41
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    Springer
    World journal of microbiology and biotechnology 14 (1998), S. 711-717 
    ISSN: 1573-0972
    Keywords: Biopiles ; bioremediation ; biosurfactants ; crude oil ; Microtox® ; Rhodococcus ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Rhodococcus strains from the culture collection at the Institute of Ecology and Genetics of Microorganisms, Perm, Russia were examined for biosurfactant production during growth on n-alkanes and the ability to remove oil associated with contaminated sands and oil shale cuttings. Members of the genus, particularly R. ruber, were shown to produce low toxicity surfactants effective in removing oil from surfaces. The extent of desorption was inversely related to the concentration of high molecular weight hydrocarbons, namely asphaltenes and resins. In addition, crude surfactant complexes enhanced the degradation of crude oil, in the short term, when added to contaminated agricultural soil during bioremediation studies utilizing biopiling technology.
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  • 42
    ISSN: 1573-1499
    Keywords: bioremediation ; Monod kinetics ; porous medium ; traveling wave
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Computer Science
    Notes: Abstract A one‐dimensional model is developed for simulating in‐situ bioremediation. The modeled processes are advective and dispersive transport, biotransformation and microbial growth. The biodegradation of the contaminant is limited by the supply of electron acceptor or microbial mass. We distinguish three regimes of oxygen consumption, a low oxygen consumption regime, an intermediate regime and a fast oxygen consumption regime. Parameter variation reveals the influence of the dimensionless numbers on the duration of the three regimes.
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  • 43
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 438-444 
    ISSN: 0006-3592
    Keywords: bioremediation ; plasma discharge ; dichlorophenol degradation ; perchloroethylene degradation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pulsed electric discharge (PED) and bioremediation were combined to create a novel two-stage system which dechlorinates the halogenated pollutants, 2,4-dichlorophenol and perchloroethylene, with repetitive (0.1-1 kHz), short pulse (∼100 ns), low voltage (40-80 kV) discharges and then mineralizes the less chlorinated products with aerobic bacteria. A 6.1 mM aqueous dichlorophenol sample was cycled through the PED reactor (60 kV of applied pulsed voltage and 300 Hz) 6 times, resulting in the release of 55% of the initial dichlorophenol chloride ions (1 mM Cl- removed each cycle). The respective average specific efficiency is 0.4-0.6 keV/(Cl- molecule). Pseudomonas mendocina KR1, which grows in minimal medium supplemented with phenol but not with dichlorophenol, increased in cell density in all cultures supplemented with the PED-treated DCP samples and yielded a maximum of two-fold additional Cl- released compared to the PED-related alone. The number of PED-treatment cycles, voltage, and frequency were also varied, showing that both cell densities and overall dichlorophenol dechlorination were highly dependent upon the number of PED-treatment cycles, rather than the tested voltages and frequencies. Using this two-stage treatment system, PED released 31% of the initial chloride ions from dichlorophenol (after three cycles at 40-45 kV and 1.2 kHz) while P. mendocina KR1 in the second stage increased dechlorination to 90%. These results were corroborated by the 35% additional chloride release found with activated sludge cultures. Perchloroethylene (0.6 mM) was similarly treated in a first-stage PED reactor (80% chloride removal after four cycles) followed by biodegradation of the dechlorinated products with a recombinant toluene o-monooxygenase-expressing Pseudomonas fluorescens strain. Gas chromatographic analysis showed that the PED reactor created less-chlorinated byproducts (i.e., trichloroethylene) that were removed (74%) upon exposure to the recombinant bacterium. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:438-444, 1998.
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  • 44
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 60 (1998), S. 204-215 
    ISSN: 0006-3592
    Keywords: immobilization ; white-rot fungi ; Lentinula edodes ; manganese peroxidase ; Mn3+ ; azlactone ; chlorophenol ; EEDQ ; biocatalyst ; bioremediation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Manganese peroxidase (MnP) purified from commercial cultures of Lentinula edodes was covalently immobilized through its carboxyl groups using an azlactone-functional copolymer derivatized with ethylenediamine and 2-ethoxy-1-ethoxycarbonyl-1,2-dihydroquinoline (EEDQ) as a coupling reagent. The tethered enzyme was employed in a two-stage immobilized MnP bioreactor for catalytic generation of chelated MnIII and subsequent oxidation of chlorophenols. Manganese peroxidase immobilized in the enzyme reactor (reactor 1) produced MnIII-chelate, which was pumped into another chemical reaction vessel (reactor 2) containing the organopollutant. Reactor 1-generated MnIII-chelates oxidized 2,4-dichlorophenol and 2,4,6-trichlorophenol in reactor 2, demonstrating a two-stage enzyme and chemical system. H2O2 and oxalate chelator concentrations were varied to optimize the immobilized MnP's oxidation of MnII to MnIII. Oxidation of 1.0 mM MnII to MnIII was initially measured at 78% efficiency under optimized conditions. After 24 h of continuous operation under optimized reaction conditions, the reactor still oxidized 1.0 mM MnII to MnIII with ∼69% efficiency, corresponding to 88% of the initial MnP activity. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 204-215, 1998.
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  • 45
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 507-516 
    ISSN: 0006-3592
    Keywords: bioremediation ; Comamonas ; nitrobenzoates ; reactor modeling ; mixed culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A model describing the transient activity of a mixed immobilized culture of Comamonas spp. JS46 and JS47 growing on mixed substrates is presented. The transient periods considered are those following changes in the feed carbon source, which alternated between meta- and para-nitrobenzoate. The feed profile alternately starved one of the species in the mixed culture. The response of the system, as quantified by the reactor effluent substrate concentrations, is dictated by the activity of the biomass and the appropriate biochemical pathway. As detailed mechanistic pathway information is not available, respirometry has been used to characterize both facets of activity. Two parameters were introduced: Ψ representing pathway activity and Γ representing biomass activity; a detailed description of the analysis is included. The model is compared to experimental investigation of the system and describes the reactor response well. The agreement between model and experiment suggests the usefulness of oxygen kinetics as global measurements to describe complex systems when mechanistic detail is not available. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59: 507-516, 1998.
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  • 46
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    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 471-476 
    ISSN: 0006-3592
    Keywords: soil immobilization ; soil pollutants ; bioremediation ; bioreactor ; biofilm ; pentachlorophenol ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A new concept for the development of microbial consortia for the degradation of persistent soil pollutants and for pollutant treatment is proposed. The concept defined as “soil immobilization” is based on the entrapment of soil particles, showing microbial activity in degrading the target pollutant, into a solid membrane with a large pore size distribution. The particular hydrodynamic and mass transfer properties of this system result in a very efficient process. A new type of bioreactor is proposed for carrying out the immobilized soil process. The performance of the system was tested by developing a microbial system for the mineralization of pentachlorophenol (PCP). The results show that the volumetric efficiency of the process for PCP mineralization in the immobilized soil bioreactor is 1-3 orders of magnitude higher than reported literature values. Chlorine and carbon atoms of PCP are both nearly completely (99%) mineralized. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 471-476, 1998.
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  • 47
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    Biotechnology and Bioengineering 57 (1998), S. 751-755 
    ISSN: 0006-3592
    Keywords: PCE ; chlorinated ethenes ; kinetics ; bioremediation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Reductive dechlorination of chlorinated ethenes has typically been modeled using standard Michaelis-Menten kinetic equations, implying that each dechlorination step is catalyzed by a unique biological factor. An alternative kinetic model is based on the assumption that all steps are mediated by a single factor. These two options are considered in the context of chlorinated ethene degradation by a previously characterized anaerobic culture. Competitive kinetics afford better chi-squared and visual fits of the data set tested. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 751-755, 1998
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  • 48
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    Biotechnology and Bioengineering 58 (1998), S. 231-239 
    ISSN: 0006-3592
    Keywords: polyphosphate metabolism ; metabolic engineering ; Escherichia coli ; bioremediation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Polyphosphate metabolism plays an important role in the bioremediation of phosphate contamination in municiple wastewater, and may play a key role in heavy metal tolerance and bioremediation. However, little is known about the regulation of polyphosphate metabolism in microorganisms and its role in heavy metal toxicity. We have manipulated polyphosphate metabolism in Escherichia coli by overexpressing the genes for polyphosphate kinase (ppk) and for polyphosphatase (ppx) under control of their native promoters and inducible promoters. Overexpression of ppk results in high levels of intracellular polyphosphate, improved phosphate uptake, but no increase in tolerance to heavy metals. Overexpression of both ppk and ppx results in lower levels of intracellular polyphosphate, secretion of phosphate from the cell, and increased tolerance to heavy metals. Metabolic flux analysis indicates that the cell responds to increased flux through the PPK-PPX pathway by altering flux through the TCA cycle. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:231-239, 1998.
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  • 49
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    Biotechnology and Bioengineering 58 (1998), S. 345-355 
    ISSN: 0006-3592
    Keywords: cyclodextrin ; polychlorobiphenyl ; chlorobenzoic acid ; soil ; bioremediation ; biodegradation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The possibility of enhancing the intrinsic ex-situ bioremediation of a chronically polychlorinated biphenyl-contaminated soil by using cyclodextrins was studied in this work. The soil, contaminated with a large array of polychlorinated biphenyls and deriving from a dump site where it has been stored for about 10 years, was found to contain indigenous cultivable aerobic bacteria capable of utilising biphenyl and chlorobenzoic acids. The soil was amended with inorganic nutrients and biphenyl, saturated with water, and treated in aerobic batch slurry- and fixed-phase reactors. Hydroxypropyl-β-cyclodextrin and γ-cyclodextrin, added to both reactor systems at the concentration of 10 g/L at the 39th and 100th days of treatment, were found to generally enhance the depletion rate and extent of the soil polychlorobiphenyls. Despite some abiotic losses could have affected the depletion data, experimental evidence, such as the production of metabolites tentatively characterized as chlorobenzoic acids and chloride ion accumulation in the reactors, indicated that cyclodextrins significantly enhanced the biological degradation of the soil polychlorobiphenyls. This result has been ascribed to the capability of cyclodextrins of enhancing the availability of polychlorobiphenyls in the hydrophilic soil environment populated by immobilised and suspended indigenous soil microorganisms. Both cyclodextrins were metabolised by the indigenous soil microorganisms at the concentration at which they were used. Therefore, cyclodextrins, both for their capability of enhancing the biodegradation of soil polychlorobiphenyls and for their biodegradability, can have the potential of being successfully used in the bioremediation of chronically polychlorinated biphenyl-contaminated soils. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58:345-355, 1998.
    Additional Material: 5 Ill.
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  • 50
    ISSN: 0006-3592
    Keywords: Comamonas ; nitrobenzoates ; bioremediation ; immobilized mixed culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The treatment of meta- and para-nitrobenzoic acid in an industrial wastestream by Comamonas sp. JS46 and Comamonas sp. JS47 is investigated. The most important feature of the wastestream is the constantly changing concentration ratio of the two isomers. The most extreme occurrence is considered here: the complete change in feed carbon source from one isomer to the other. A series of immobilized cell airlift reactor experiments are described to examine the operation and response of the system to these changes in the feed carbon source. Separate reactors containing each species immobilized are compared with a reactor containing both species immobilized within the same bead, and to a reactor containing both species with each species confined to separate beads. On the basis of response time necessary to recover the appropriate activity, the reactor containing both species immobilized within the same bead offers the most effective arrangement. Interactions occurring between the two organisms in the coimmobilized system, mediated by the nitrobenzoate metabolites, are discussed relative to the improved response of this arrangement. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59:21-27, 1998.
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  • 51
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    Biotechnology and Bioengineering 59 (1998), S. 520-523 
    ISSN: 0006-3592
    Keywords: haloalkane dehalogenase ; protein engineering ; bioremediation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We attempted to expand the range of chlorinated solvents degraded by Xanthobacter autotrophicus GJ10 to include trichloroethylene by the rational modification of the enzyme haloalkane dehalogenase. The amino acids Phe164, Asp170, Phe172 and Trp175 were individually replaced with alanine by site-directed mutagenesis. All substitutions produced enzymes with lower than wild type activity with 1,2-dichloroethane. The Phe164Ala and Asp170Ala mutants were 3 and 2 times more active than was the wild type enzyme in dechlorinating 1,6-dichlorohexane. The Asp170Ala mutant resembled the wild type enzyme in its relative activity against longer chain substrates. No mutant was active with trichloroethylene. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59: 520-523, 1998.
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  • 52
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    Yeast 14 (1998), S. 1069-1087 
    ISSN: 0749-503X
    Keywords: amines and amides ; biodetergents ; biocides ; bioremediation ; biosensors ; Candida rugosa ; carbohydrate esters ; cosmetics and perfumery ; food and flavour ; immobilisation ; isoenzymes ; lipases ; molecular biology ; pharmaceuticals ; single cell protein ; specificity ; tanning ; ultra-structure ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: This review describes how the versatile Candida rugosa lipases (CRL) have extended the frontiers of biotechnology. As evidenced by the current literature, CRL claims more applications than any other biocatalyst. This review comprises a detailed discussion on the molecular biology of CRL, its versatile catalytic reactions, broad specificities and diverse immobilization strategies. It also discusses its role in the food and flavour industry, the production of ice cream and single cell protein, biocatalytic resolution of life-saving pharmaceuticals, carbohydrate esters and amino acid derivatives unobtainable by conventional chemical synthesis, potent biocide making, biosensor modulations, eco-friendly approach and bioremediation, biosurfactants in detergent making, and recently, cosmetics and perfumery. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
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  • 53
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    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 71 (1998), S. 15-26 
    ISSN: 0268-2575
    Keywords: bioremediation ; Citrobacter ; lanthanum ; uranium ; thorium ; plutonium ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Removal of La3+, UO22+ and Th4+ from aqueous solution by a Citrobacter sp. was dependent on phosphatase-mediated phosphate release and the residence time in a plug-flow reactor (PFR) containing polyacrylamide gel-immobilized cells. In a stirred tank reactor (STR) lanthanum phosphate accumulated on the biomass rapidly, in preference to uranium or thorium phosphates. Thorium removal was not affected by the presence of uranium but was promoted in the presence of lanthanum. Analysis of the accumulated polycrystalline material by X-ray powder diffraction (XRD) analysis and proton induced X-ray emission (PIXE) suggested the formation of a mixed crystal of lanthanum and thorium phosphate. La3+, UO22+ and Th4+ are analogues of the corresponding species of Pu3+, PuO22+ and Pu4+. The La/U/Th model system was used to identify some potential problems in the bioremediation of wastes containing plutonium and to develop a method for the biologically-mediated removal of plutonium from solution, in a test solution of 239Pu ‘spiked’ with a 241Pu tracer. © 1998 SCI.
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  • 54
    ISSN: 1572-9729
    Keywords: bioremediation ; bioslurry reactor ; explosive ; microcosm ; mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Microcosm tests simulating bioslurry reactors with 40% soilcontent, containing high concentrations of TNT and/or RDX,and spiked with either 14C]-TNT or14C]-RDX were conducted to investigate the fate ofexplosives and their metabolites in bioslurry treatment processes.RDX is recalcitrant to indigenous microorganisms in soil andactivated sludge under aerobic conditions. However, soilindigenous microorganisms alonewere able to mineralize 15% of RDX to CO2 underanaerobic condition, and supplementation of municipal anaerobicsludge as an exogenous source of microorganismssignificantly enhanced the RDX mineralization to 60%. RDXmineralizing activity of microorganisms in soil and sludge wassignificantly inhibited by the presence of TNT. TNTmineralization was poor (〈 2%) and was not markedlyimproved by the supplement ofaerobic or anaerobic sludge. Partitioning studies of14C]-TNT in the microcosmsrevealed that the removal of TNTduring the bioslurry process was due mainly to thetransformation of TNT and irreversiblebinding of TNT metabolites onto soil matrix. In the case ofRDX under anaerobic conditions,a significant portion (35%) of original radioactivity wasalso incorporated into the biomass andbound to the soil matrix.
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  • 55
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    Biodegradation 8 (1997), S. 349-356 
    ISSN: 1572-9729
    Keywords: biodegradation ; bioremediation ; acclimation ; Everglades ; mineralization ; nitrophenol ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The Everglades in South Florida are a unique ecologicalsystem. As a result of the widespread use of pesticides andherbicides in agricultural areas upstream from these wetlands,there is a serious potential for pollution problems in theEverglades. The purpose of this study was to evaluate theability of indigenous microbial populations to degradexenobiotic organic compounds introduced by agricultural andother activities. Such biodegradation may facilitate theremediation of contaminated soils and water in the Everglades.The model compound selected in this study is 4-nitrophenol, achemical commonly used in the manufacture of pesticides. Themineralization of 4-nitrophenol at various concentrations wasstudied in soils collected from the Everglades. Atconcentrations of 10 and 100 µg/g soil, considerablemineralization occurred within a week. At a higherconcentration, i.e., 10 mg/g soil, however, no mineralizationof 4-nitrophenol occurred over a 4-month period; such a highconcentration apparently produced an inhibitory effect. Therate and extent of 4-nitrophenol mineralization was enhancedon inoculation with previously isolated nitrophenol-degradingmicroorganisms. The maximum mineralization extent measured,however, was less than 30% suggesting conversion to biomassand/or unidentified intermediate products. These resultsindicate the potential for natural mechanisms to mitigate theadverse effects of xenobiotic pollutants in a complex systemsuch as the Everglades.
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  • 56
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    Biodegradation 8 (1997), S. 401-417 
    ISSN: 1572-9729
    Keywords: bioavailability ; biodegradation ; bioremediation ; mass transfer ; soil sanitation ; surfactants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Biodegradation of hydrophobic organic compounds in polluted soil is a process involving interactions among soil particles, pollutants, water, and micro-organisms. Surface-active agents or surfactants are compounds that may affect these interactions, and the use of these compounds may be a means of overcoming the problem of limited bioavailability of hydrophobic organic pollutants in biological soil remediation. The effects of surfactants on the physiology of micro-organisms range from inhibition of growth due to surfactant toxicity to stimulation of growth caused by the use of surfactants as a co-substrate. The most important effect of surfactants on the interactions among soil and pollutant is stimulation of mass transport of the pollutant from the soil to the aqueous phase. This can be caused by three different mechanisms: emulsification of liquid pollutant, micellar solubilisation, and facilitated transport. The importance of these mechanisms with respect to the effect of surfactants on bioavailability is reviewed for hydrophobic organic pollutants present in different physical states. The complexity of the effect of surfactants on pollutant bioavailability is reflected by the results in the literature, which range from stimulation to inhibition of desorption and biodegradation of polluting compounds. No general trends can be found in these results. Therefore, more research is necessary to make the application of surfactants a standard tool in biological soil remediation.
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  • 57
    ISSN: 1573-1499
    Keywords: bioremediation ; numerical simulation ; carbon tetrachloride ; denitrification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Computer Science
    Notes: Abstract When injecting nutrients during active bioremediation, various nutrient addition strategies can be employed in order to remediate the site at minimal expense. In particular, if more than one nutrient is required, a pulse addition strategy can be devised in which these nutrients are added as temporally separated pulses such that the biostimulated portion of the flow field can be maximized. In this manuscript, results of numerical simulations are reported which demonstrate this effect. Previously published kinetic expressions describing microbial growth and carbon tetrachloride degradation under denitrifying conditions are used in these simulations. The simulations indicate that volumetric treatment can be accomplished by injecting long duration nutrient pulses of different nutrients that are separated by a long period where only unamended water is injected. This strategy will cause the nutrient pulses to overlap at a considerable distance from the injection point, while maintaining concentrations that are high enough to ensure significantbiomass growth and contaminant destruction.
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  • 58
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    Plant and soil 192 (1997), S. 219-226 
    ISSN: 1573-5036
    Keywords: barley ; bioremediation ; hydrocarbon ; hydrocarbon contamination ; plant growth ; soil contamination ; soil water ; soil water properties ; water repellency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Much effort has been focused on defining the end-point of bioremediated soils by chemical analysis toxicity tests. However, these tests do not assess the quality, or the capability, of soil to support plant growth after bioremediation. We studied the response of plants to hydrocarbon contaminants by camparing barley (Hordeum vulgare) growth on: (i) control soil, agricultural topsoil, (ii) oil-contaminated soil (40,000 mg kg−1 total extractable hydrocarbons, or TEH), and (iii) oil-contaminated soil treated by bioremediation (20,000 mg kg−1 TEH). Barley growth and yield was significantly reduced by oil-contamination. Bioremediation did not improve yield of barley and shoot dry mass was slightly reduced after bioremediation. The lack of effect from bioremediation is attributed to poor soil water sorption, which was negatively influenced by hydrocarbon residuals. We concluded that the soil-water relation is one of the most important factors in assessing endpoint of bioremediated soils for plant growth.
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  • 59
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    Plant and soil 192 (1997), S. 227-236 
    ISSN: 1573-5036
    Keywords: bioremediation ; hydrocarbon ; hydrocarbon contamination ; soil contamination ; soil water ; soil water properties ; water repellency
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This study was conducted to investigate water movement in hydrocarbon contaminated soils. Three soils were studied, a hydrocarbon contaminated soil, the same soil after 3 years of bioremediation, and a control soil from the same site. There was a critical soil water content around 18% (bioremediated soil) and 20% (contaminated soil), above which the sorptivity of the contaminated soil was near that of the control soil. For soils with water contents below this value, there was a strong divergence in sorptivity between contaminated and control or bioremediated soils. Results suggest that water availability in contaminated soils will be highly dependent on soil water properties as water potential approaches the permanent wilting point (-1.5 MPa matrix potential). Infiltration of water into air dry (2% m.c. w/w) hydrocarbon contaminated soils was up to three orders of magnitude slower than for the control soil. For air dried soils, the infiltration rate of the contaminated and bioremediated soils was constant with time. This was in contrast to the control soil where infiltration rate was a function of the reciprocal of the square root of time.
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  • 60
    ISSN: 1572-9699
    Keywords: 16S rRNA ; Biolog™ ; bioremediation ; phenotype ; phospholipid ester-linked fatty acid (GC-FAME) ; phylogeny ; polycyclic aromatic hydrocarbons (PAHs) taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The diversity of bacteria isolated from creosote- contaminated soils in the United States, Norway, and Germany was determined by comparing their ability to degrade polycyclic aromatic hydrocarbons (PAHs), their phospholipid ester-linked fatty acid (GC-FAME) profiles, sole carbon source utilization patterns (Biolog™ assays (Use of trade names or specific products does not imply endorsement by the U.S. EPA.), and 16S rRNA sequences. Bacteria were initially obtained by enrichment with phenanthrene and fluoranthene. Many were capable of degrading a broad range of the PAHs found in creosote. Phenanthrene- or fluoranthene- degraders were abundant in most of the soils tested. Several of the fluoranthene-degrading isolates clustered with Sphingomonas (formerly Pseudomonas) paucimobilis strain EPA505 in the GC-FAME and Biolog™ analyses and three of the isolates examined by 16S rRNA sequence comparisons showed a close relationship with Sphingomonas. In addition, the Sphingomonas strains showed the most extensive degradation of 4- & 5-ring PAHs in creosote. Burkholderia cepacia strains isolated on phenanthrene from PAH-contaminated soils had limited ability to attack higher molecular weight PAHs either individually or in creosote. Thus, PAH degradation capabilities appeared to be associated with members of certain taxa, independent of the origin of the soils from which the bacteria were isolated.
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  • 61
    ISSN: 1572-9729
    Keywords: biodegradation ; PAH ; phenanthrene ; pyrene ; bioremediation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of several bioremediation stimulants, including potentialmetabolism pathway inducers, inorganic/organic nutrients, and surfactants onthe metabolism of phenanthrene and pyrene, as well as the populationdynamics of PAH degrading microorganisms was examined in five soils withdiffering background PAH concentrations, exposure histories and physicalproperties. Most of the supplements either had no significant effect ordecreased the mineralization of [14C]-phenanthrene and[14C]-pyrene in soil slurry microcosms. The effect of aparticular supplement, however, was often not uniform within or acrosssoils. Decreased mineralization of [14C]-phenanthrene and[14C]-pyrene was usually due to either preferential use of thesupplement as carbon source and/or stimulation of non-PAH degradingmicroorganisms. Many of the supplements increased populations ofheterotrophic microorganisms, as measured by plate counts, but did notincrease populations of phenanthrene degrading microorganisms, as measuredby the [14C]-PAH mineralization MPN analysis or cellularincorporation of [14C]-PAH. These results suggest that the PAHdegrading community at each site may be unique in their response tomaterials added in an attempt to stimulate PAH degradation. Thecharacteristics of the site, including exposure history, soil type, andtemporal variation may all influence their response.
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  • 62
    ISSN: 1572-9729
    Keywords: bioremediation ; denitrification ; ferrous iron ; naphthalene ; nutrients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The feasibility of aerobic in situ bioremediation isbeing investigated for use in a strategy to controlsubsurface coal tar contamination at the site of aformer manufactured gas plant. As part of thisinvestigation, anoxic aquifer sands collected between11 and 25 m below ground surface were assayed in batchmicrocosms to measure the singular and combinedeffects of O2, NO3 -, andPO4 3- on 14C-naphthalenemineralization. The influence of these additivesvaried considerably between sediments. A high initialconcentration of O2 (21 mg/L) promoted thegreatest extent of mineralization in the majority ofactive sediments. NO3 - (85 mg/L) wasobserved to enhance, inhibit, or have no effect on therate of naphthalene mineralization, althoughsignificant denitrification was observed in nearly allthe active sediments. Data suggest thatPO4 3- complexation and/or precipitation withsediment cations limited P bioavailability. Thesediments that were incapable of mineralizingnaphthalene were characterized by low pH (〈 4.1),high SO4 2- (〉 500 mg/L), and moderate tohigh dissolved Fe(II) (30–265 mg/L) whenequilibrated aerobically with water. Fe(II) likelyexerted a significant O2 demand that reduced theO2 available as an electron acceptor forbiodegradation. These experiments demonstrate thatwhile aeration/oxygenation can be an effectivestrategy for enhancing subsurface bioremediation ofaromatic hydrocarbons, the biodegradation response toaeration/oxygenation and nutrient addition may varyconsiderably within an aquifer.
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  • 63
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    Water, air & soil pollution 95 (1997), S. 165-178 
    ISSN: 1573-2932
    Keywords: bioremediation ; phytoremediation ; polycyclic aromatic hydrocarbons ; petroleum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Rhizosphere microbial populations may increase bioremediation of soil contaminated with organic chemicals. A growth chamber study was conducted to evaluate rhizosphere microbial populations in contaminated and non-contaminated soil. Alfalfa (Medicago sativa L.) and alpine bluegrass (Poa alpina L.) were grown in soil containing a mixture of organic chemicals for 14 weeks. The equal millimolar mixture of hexadecane, (2,2-dimethylpropyl)benzene, cis-decahydronaphthalene (decalin), benzoic acid, phenanthrene, and pyrene was added at levels of 0 and 2000 mg/kg. Organic chemical degrader (OCD) populations were assessed by a Most-Probable-Number technique, and bacteria and fungi were enumerated by plate count methods. Different methods for expressing OCD rhizosphere populations were investigated to determine the effect it had on interpretation of the results. At 9 weeks, the OCD numbers were significantly higher in rhizosphere and contaminated soils than in bulk and non-contaminated soils, respectively. Alfalfa rhizosphere OCD levels were 4 × 107/g for contaminated and 6 × 106/g for non-contaminated soils. Bluegrass rhizosphere OCD levels were 1 × 107/g and 1 × 106/g in contaminated and non-contaminated soils, respectively. Selective enrichment of OCD populations was observed in contaminated rhizosphere soil. Higher numbers of OCD in contaminated rhizospheres suggest potential stimulation of bioremediation around plant roots.
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  • 64
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    Water, air & soil pollution 95 (1997), S. 165-178 
    ISSN: 1573-2932
    Keywords: bioremediation ; phytoremediation ; polycyclic aromatic hydrocarbons ; petroleum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Rhizosphere microbial populations may increase bioremediation of soil contaminated with organic chemicals. A growth chamber study was conducted to evaluate rhizosphere microbial populations in contaminated and non-contaminated soil. Alfalfa (Medicago sativa L.) and alpine bluegrass (Poa alpina L.) were grown in soil containing a mixture of organic chemicals for 14 weeks. The equal millimolar mixture of hexadecane, (2,2-dimethyl-propyl)-benzene, cis-decahydronaphthalene (decalin), benzoic acid, phenanthrene, and pyrene was added at levels of 0 and 2000 mg/kg. Organic chemical degrader (OCD) populations were assessed by a Most-Probable-Number technique, and bacteria and fungi were enumerated by plate count methods. Different methods for expressing OCD rhizosphere populations were investigated to determine the effect it had on interpretation of the results. At 9 weeks, the OCD numbers were significantly higher in rhizosphere and contaminated soils than in bulk and non-contaminated soils, respectively. Alfalfa rhizosphere OCD levels were 4 × 107/g for contaminated and 6 × 106/g for non-contaminated soils. Bluegrass rhizosphere OCD levels were 1 × 107/g and 1 × 106/g in contaminated and non-contaminated soils, respectively. Selective enrichment of OCD populations was observed in contaminated rhizosphere soil. Higher numbers of OCD in contaminated rhizospheres suggest potential stimulation of bioremediation around plant roots.
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  • 65
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    Biotechnology and Bioengineering 55 (1997), S. 182-190 
    ISSN: 0006-3592
    Keywords: dechlorination ; bioremediation ; PCBs ; sediments ; anaerobic granules ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A polychlorinated biphenyl (PCB)-dechlorinating anaerobic microbial consortium, developed in a granular form, demonstrated extensive dechlorination of PCBs present in Raisin River sediments at room (20° to 22°C) and at a relatively low (12°C) temperature. Highly chlorinated PCB congeners were dechlorinated and less chlorinated compounds were produced. The homolog comparison showed that tri-, tetra-, penta-, hexa-, and heptachlorobiphenyl compounds decreased significantly, and mono- and dichlorobiphenyl compounds increased. After 32 weeks of incubation at 12°C, the predominant less chlorinated products included 2-, 4-, 2-2/26-, 24-, 2-4-, 24-2-, 26-2-, and 26-4-CB. Among these, 24- and 24-2-CB did not accumulate at room temperature, suggesting a further dechlorination of these congeners. Predominantly meta dechlorination (i.e., pattern M) was catalyzed by the microbial consortium in the granules. Dechlorination in the control studies without granules was not extensive. This study is the first demonstration of enhanced reductive dechlorination of sediment PCBs by an exogenous anaerobic microbial consortium. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 182-190, 1997.
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  • 66
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    Biotechnology and Bioengineering 56 (1997), S. 361-371 
    ISSN: 0006-3592
    Keywords: biofilms ; bioremediation ; toluene ; vapor phase bioreactors ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A Pseudomonas putida 54G biofilm was grown on toluene vapor supplied as the sole external carbon and energy source in a flat plate biofilm reactor. Enumerations of cells in the biofilm were made using culture techniques (selective and nonselective for toluene) and microscopic techniques (total and respiring cells), and an analysis of the progression of the state of the culture was made by examination of various fractions of the populations. Long-term exposure to higher levels of toluene produced the following trends: (i) lower fraction of total cells that respired; (ii) lower fraction of culturable cells that also grew on toluene; (iii) higher fraction of respiring cells that could not grow on toluene plates; and (iv) a relatively constant fraction of total cells that could not be cultured on toluene. Respiration rate was determined using oxygen microsensors, and the fraction of the total respiration that was not associated with toluene uptake increased with higher toluene exposure. A combination of cryosectioning and respiration rate data was used to demonstrate that more respiring cells and a higher respiration rate both occurred at the base of the film, suggesting a deterioration in physiological state with continued exposure to toluene. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 361-371, 1997.
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  • 67
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    Journal of Chemical Technology AND Biotechnology 70 (1997), S. 331-336 
    ISSN: 0268-2575
    Keywords: polycyclic aromatic hydrocarbons ; petrochemical sludge ; polluted soil ; bioremediation ; gas chromatography ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Bioremediation is capable of reducing the hydrocarbon concentration of contaminated soil by 75-95% depending on the soil type, the kind of hydrocarbons and the history of the contamination. The impact of different number of petrochemical sludge applications to soil on the degree of PAH elimination was assessed. A simple and reliable extraction and gas chromatographic method was used to facilitate more rapid determination of hydrocarbon contamination in soils and sludge wastes. Its application in a model laboratory bioremediation experiment and a pilot field study were used to illustrate its practical benefits. Post-remediation persistence of sludge constituents was evaluated after a single dose sludge application in the laboratory and after seven sludge applications in the field. A relative increase in the concentration of some PAHs was detected at the end of the experiments, but their individual concentrations were reduced to suggested values for industrial soils. The remaining concentration of total hydrocarbons in soil was found to be similar in both experiments, pointing to soil organic matter adsorption capacity as the factor determining hydrocarbon elimination limits in soil bioremediation. ©1997 SCI
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  • 68
    ISSN: 0268-2575
    Keywords: bioremediation ; diesel-oil ; inoculum ; cold-adapted microorganisms ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Laboratory bioremediation experiments were performed with soil from a diesel-oil contaminated waste disposal site; contamination was 5580 mg hydrocarbons per kg soil dry mass. The effects of incubation temperatures (10°C and 25°C), of the addition of an inorganic fertilizer at C: N ratios of 10:1 and 50:1, of the indigenous soil microorganisms and of a psychrotrophic and a mesophilic inoculum capable of degrading diesel-oil were investigated. The highest diesel-oil decontamination rates were 43% at 10°C and 55% at 25°C after 30 days. The biodegradation activity of the indigenous soil microorganisms was highly increased by the use of fertilizers. The diesel-oil degradation activity of the added inocula was highest when no fertilizer was present and was inhibited by nutrient supply. Abiotic processes did not contribute to diesel-oil elimination. ©1997 SCI
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  • 69
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    Journal of Chemical Technology AND Biotechnology 69 (1997), S. 107-113 
    ISSN: 0268-2575
    Keywords: bioremediation ; dechlorination ; degradation ; induction ; pentachlorophenol ; Pseudomonas sp ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: -The effect of selected variables on pentachlorophenol (PCP) dechlorination and degradation by a PCP-mineralizing Pseudomonas sp. UG30 was studied. Maximum rates of PCP dechlorination and degradation increased linearly with increasing initial cell densities up to 1·1×109 CFU cm-3 and then levelled off. Maximum rates of PCP dechlorination and degradation decreased as the initial PCP concentration increased. Degradation of 400 ppm PCP was incomplete and stopped when 120 ppm Cl- was released into the medium. It was found that Cl- ions inhibited PCP degradation at a concentration of 100 ppm and higher. Enzymes involved in PCP dechlorination and degradation by UG30 cells were inducible, but not repressed by glucose. UG30 cultures were able to degrade PCP at 10°C and rates increased linearly with increasing temperature to 30°C. Apparent activation energies for PCP dechlorination and degradation were 7·72 and 9·13 kcal mol-1, respectively. © 1997 SCI.
    Additional Material: 7 Ill.
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  • 70
    ISSN: 1572-9729
    Keywords: bioremediation ; petroleum ; mutagenicity ; crude oil degradation ; fungal degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Two fungal strains, Cunninghamella elegans and Penicillium zonatum, that grow with crude oil as a sole carbon source were exposed to three crude oils that exhibit a range of mutagenic activity. At regular time intervals following fungal incubation with the various crude oils, extracts were tested for the presence of mutagenic activity using the spiral Salmonella assay. When the most mutagenic of the oils, Pennsylvania crude oil, was degraded by C. elegans or by P. zonatum, its mutagenicity was significantly reduced; corresponding uninoculated (weathered) controls of Pennsylvania crude remained mutagenic. West Texas Sour crude oil, a moderately mutagenic oil, exhibited little change in mutagenicity when incubated with either C. elegans or P. zonatum. Swanson River Field crude oil from Cook Inlet, Alaska is a slightly mutagenic oil that became more mutagenic when incubated with C. elegans; weathered controls of this oil showed little change in mutagenicity. Mycelial mat weights measured during growth on crude oils increased corresponding to the biodegradation of about 25% of the crude oil.
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  • 71
    ISSN: 1572-9729
    Keywords: biodegradation ; methane formation ; phthalic acid esters ; landfills ; bioremediation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Anaerobic microorganisms in municipal solid waste samples from laboratory-scale landfill reactors and a pilot-plant biogas digestor were investigated with the aim of assessing their ability to transform four commercially used phthalic acid esters (PAEs) and phthalic acid (PA). The PAEs studied were diethyl phthalate (DEP), butylbenzyl phthalate (BBP), dibutyl phthalate (DBP) and bis(2-ethylhexyl) phthalate (DEHP). No biological transformation of DEHP could be detected in any of the experiments. Together with waste samples from the simulated landfilling conditions, the PAEs (except DEHP) were hydrolytically transformed to their corresponding monoesters. These accumulated as end products, and in most cases they were not further degraded. During incubation with waste from the biogas digestor, the PAEs (except DEHP) were completely degraded to methane and carbon dioxide. The influence of the landfill development phase on the transformations was investigated utilizing PA and DEP as model substances. We found that during both the intense and stable methanogenic (but not the acidogenic) phases, the microoganisms in the samples had the potential to transform PA. A shorter lag phase was observed for the PA transformation in the samples from the stable methanogenic phase as compared with earlier phases. This indicates an increased capacity to degrade PA during the aging phases of the municipal solid waste in landfills. No enhancement of the DEP transformation could be observed as conditions in the methanogenic landfill model changed over a year's time. The results indicate that microorganisms developing in a methanogenic landfill environment have a substantially lower potential to degrade PAEs compared with those developing in a biogas reactor.
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  • 72
    ISSN: 1572-9729
    Keywords: biodegradation ; bioremediation ; mathematical modeling ; soil respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Mineralization rates of non-volatile petroleum hydrocarbons (HCs) in five different oil-contaminated soils with initial HC contents ranging from 0.1 to 13 g kg-1 are estimated as a function of environmental factors. The aim of the study is threefold, (i) to study the relevance of environmental factors that may influence the mineralization rate, (ii) to compare mineralization rates estimated in two experiments at different scales, after standardizing them to environmental reference conditions, (iii) to evaluate the CO2 production rate as a measure for the mineralization rate of HCs. Experiments were performed at laboratory scale (30–50 cm3 soil volume) in closed-jars under constant environmental conditions and in lysimeters (0.81 m3 soil volume) under dynamic climatic and hydrological conditions. A biodegradation model, coupled to transport models for soil heat, water, and gas dynamics is employed for data interpretation. The transport models are used to simulate the environmental conditions that influence the mineralization rate in the non-steady lysimeter experiments. The results show that temperature, O2 concentration and HC content have an effect on the mineralization rates. Water content could not be identified as a direct governing environmental factor. However, an indirect effect of water content is that it influences the effective gas diffusion coefficient in soils. The CO2 production rate seems to be a good quantity to express the mineralization rate of HCs for HC contents〉1 g kg-1. Measured CO2 production rates standardized to reference conditions are similar for the two different experimental scales. This demonstrates that the usage of biodegradation rates obtained in the laboratory to predict the biodegradation rates under field conditions is sound, as long as the differences in environmental conditions have been taken into account.
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  • 73
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    Journal of industrial microbiology and biotechnology 16 (1996), S. 79-101 
    ISSN: 1476-5535
    Keywords: alginate ; bacteria ; biodegradation ; bioremediation ; κ-carrageenan ; encapsulation ; immobilization ; microorganisms ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Immobilized microbial cells have been used extensively in various industrial and scientific endeavours. However, immobilized cells have not been used widely for environmental applications. This review examines many of the scientific and technical aspects involved in using immobilized microbial cells in environmental applications, with a particular focus on cells encapsulated in biopolymer gels. Some advantages and limitations of using immobilized cells in bioreactor studies are also discussed.
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  • 74
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    Journal of industrial microbiology and biotechnology 17 (1996), S. 41-46 
    ISSN: 1476-5535
    Keywords: metallothionein ; cyanobacteria ; metals ; bioremediation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A cDNA encoding mouse metallothionein was cloned into the shuttle vector pUC303, creating a translational fusion with the bacterial chloramphenicol acetyltransferase gene. The resulting fusion protein has been expressed in the cyanobacteriumSynechococcus PCC7942. Cyanobacterial transformants expressed mouse metallothionein-specific mRNA species as detected by RNA slot blots. In addition, the transformants expressed a unique cadmium ionbinding protein corresponding to the predicted size of the mouse metallothionein fusion protein. Expression of this fusion protein conferred a two-to five-fold increase in cadmium ion tolerance and accumulation onSynechococcus PCC7942.
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  • 75
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    Journal of industrial microbiology and biotechnology 17 (1996), S. 116-123 
    ISSN: 1476-5535
    Keywords: sulphate-reducing bacteria ; bioremediation ; complex nitrogen sources ; substrates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Detailed nutrient requirements were determined to maximise efficacy of a sulphate-reducing bacterial mixed culture for biotechnological removal of sulphate, acidity and toxic metals from waste waters. In batch culture, lactate produced the greatest biomass, while ethanol was more effective in stimulating sulphide production and acetate was less effective. The presence of additional bicarbonate and H2 only marginally stimulated sulphide production. The sulphide output per unit of biomass was greatest using ethanol as substrate. In continuous culture, ethanol and lactate were used directly as efficient substrates for sulphate reduction while acetate yielded only slow growth. Glucose was utilised following fermentation to organic acids and therefore had a deleterious effect on pH. Ethanol was selected as the most efficient substrate due to cost and efficient yield of sulphide. On ethanol, the presence of additional carbon sources had no effect on growth or sulphate reduction in batch culture but the presence of complex nitrogen sources (yeast extract or cornsteep) stimulated both. Cornsteep showed the strongest effect and was also preferred on cost grounds. In continuous culture, cornsteep significantly improved the yield of sulphate reduced per unit of ethanol consumed. These results suggest that the most efficient nutrient regime for bioremediation using sulphate-reducing bacteria required both ethanol as carbon source and cornsteep as a complex nitrogen source.
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  • 76
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    World journal of microbiology and biotechnology 12 (1996), S. 207-212 
    ISSN: 1573-0972
    Keywords: Alkenylbenzenes ; biodegradation ; bioremediation ; microorganisms ; styrene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Alkenylbenzenes are produced in large quantities by the petrochemical industry. The simplest of these alkenylbenzenes, styrene, is in widespread use in the polymer-processing industry and is thus found in many industrial effluents. Airborne gaseous emissions of styrene are particular problems due to the potential toxicity and carcinogenicity of the compound. The catabolic pathways involved in the degradation of styrene have been well characterised. With an increased knowledge of the adaptative response which microorganisms exhibit when exposed to higher styrene concentrations, together with an understanding of the genetic regulation of the catabolic pathways which operate in these microbial strains, it is likely that these organisms could be exploited in areas such as biotransformations, biocatalysis and bioremediation.
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  • 77
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    World journal of microbiology and biotechnology 12 (1996), S. 457-461 
    ISSN: 1573-0972
    Keywords: Biomethanation ; bioremediation ; cleaner technology ; desulphurization ; gene probes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The emergence and acceptance of the concept of sustainable development warrants that the scope of environmental biotechnology be enlarged to address issues like environmental monitoring, restoration of environmental quality, resource/residue/waste-recovery/utilization/treatment, and substitution of the non-renewable resource base with renewable resources. This paper delineates the current and prospective applications in these sub-areas of environmental biotechnology, and documents case studies on environmental monitoring (enteric viruses), restoration of environmental quality (oil spill remediation), resource recovery (hydrocarbon recovery from oily sludges, biosurfactants from distillery spentwash, desulphurization of coal & sour gases), and substitution of non-renewable resources with renewables (conversion of lignocellulisics into value added chemicals).
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  • 78
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    Biotechnology and Bioengineering 51 (1996), S. 551-557 
    ISSN: 0006-3592
    Keywords: denitrify ; carbon tetrachloride ; chloroform ; acetate ; nitrate ; bioremediation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Fed batch experiments were performed to test the effects of electron donor and electron acceptor availability on the production of chloroform (CF) during carbon tetrachloride (CT) destruction by a denitrifying bacterial consortium. In one series of tests, acetate (electron donor) was present in excess while nitrate and nitrite (electron acceptor) were limiting. In the other series of tests, acetate was the limiting nutrient, and nitrate and nitrite were in excess. Under nitrate limiting conditions, 50% (±17%) of the CT transformed by the microorganisms was converted to CF. However, under acetate limiting conditions, only 4% (±4%) of the CT that was degraded appeared as CF. Previous research had suggested that denitrifying bacteria can degrade CT via two competing pathways. One of these pathways produces CF as the predominant end product. The second pathway produces CO2 as the primary end product. The results shown here suggest that the first pathway is dominant when nitrate and nitrite are depleted while the second pathway, which produces little CF, dominates when nitrate or nitrite are available.
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  • 79
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    Journal of Chemical Technology AND Biotechnology 66 (1996), S. 300-304 
    ISSN: 0268-2575
    Keywords: waste gases ; flue gases ; BTEX ; VOC ; bioremediation ; biodegradation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Three identical biofilters, run under the same conditions but inoculated with different mixed cultures, were fed a mixture of toluene, ethylbenzene, and o-xylene (TEX) gases. Inert porous perlite was used as support material, in contrast to the more conventional biofiltration systems where natural supports are used. Biodegradation started in all three biofilters a few hours after inoculation, without previous adaptation of the inocula to the toxic mixture. Despite acidification of the systems to pH values below 4·5, the elimination capacities reached were fully satisfactory. The best performing biofilter, in which bacteria were dominant, showed an elimination capacity of 70 g TEX m-3 h-1 with a near complete removal of the mixture up to an influent concentration of 1200 mg TEX m-3 at a gas residence time of 57 s. Most of the ingoing carbon was recovered as carbon dioxide in the outgoing gas. In the other biofilters fungi dominated and performance was slightly worse. With single substrates, the elimination capacity was higher for toluene and ethylbenzene than for the TEX mixture, whereas o-xylene removal was slowest in all cases. Also when feeding the mixture to the biofilters, o-xylene was removed most slowly.
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  • 80
    ISSN: 1572-9699
    Keywords: xenobiotics ; chloroaromatics ; nitroaromatics ; azo dyes ; aromatic amines ; recalcitrance ; bioremediation ; sequential-degradation ; synchronous-degradation ; mineralization ; polymerization ; oxygen tolerance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Toxic aromatic pollutants, concentrated in industrial wastes and contaminated sites, can potentially be eliminated by low cost bioremediation systems. Most commonly, the goal of these treatment systems is directed at providing optimum environmental conditions for the mineralization of the pollutants by naturally occurring microflora. Electrophilic aromatic pollutants with multiple chloro, nitro and azo groups have proven to be persistent to biodegradation by aerobic bacteria. These compounds are readily reduced by anaerobic consortia to lower chlorinated aromatics or aromatic amines but are not mineralized further. The reduction increases the susceptibility of the aromatic molecule for oxygenolytic attack. Sequencing anaerobic and aerobic biotreatment steps provide enhanced mineralization of many electrophilic aromatic pollutants. The combined activity of anaerobic and aerobic bacteria can also be obtained in a single treatment step if the bacteria are immobilized in particulate matrices (e.g. biofilm, soil aggregate, etc.). Due to the rapid uptake of oxygen by aerobes and facultative bacteria compared to the slow diffusion of oxygen, oxygen penetration into active biofilms seldom exceeds several hundred micrometers. The anaerobic microniches established inside the biofilms can be applied to the reduction of electron withdrawing functional groups in order to prepare recalcitrant aromatic compounds for further mineralization in the aerobic outer layer of the biofilm. Aside from mineralization, polyhydroxylated and chlorinated phenols as well as nitroaromatics and aromatic amines are susceptible to polymerization in aerobic environments. Consequently, an alternative approach for bioremediation systems can be directed towards incorporating these aromatic pollutants into detoxified humic-like substances. The activation of aromatic pollutants for polymerization can potentially be encouraged by an anaerobic pretreatment step prior to oxidation. Anaerobic bacteria can modify aromatic pollutants by demethylating methoxy groups and reducing nitro groups. The resulting phenols and aromatic amines are readily polymerized in a subsequent aerobic step.
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  • 81
    ISSN: 1572-9729
    Keywords: bioremediation ; pentachlorophenol ; pressure-treated timber ; Phanerochaete chrysosporium ; Flavobacterium ; Rhodococcus chlorophenolicus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The reduction of pentachlorophenol in treated timber, after inoculation with pentachlorophenol-degrading bacterial species,Rhodococcus chlorophenolicus andFlavobacterium sp., and the white-rot fungusPhanerochaete chrysosporium, was monitored in solid substrate systems and in liquid culture suspensions. In solid substrate systems there was no significant pentachlorophenol degradation by the bacterial species under a variety of conditions. Under similar conditions,Phanerochaete chrysosporium transformed over 80% of the starting concentration of 500 ppm to pentachloroanisole. In liquid culture suspensions however, mid-exponential phaseFlavobacterium sp. cells were able to degrade over 99% of the pentachlorophenol in sawdust and wood chips due to the extraction of PCP from the timber as a water soluble salt. There were however no significant changes in the chlorinated dioxin components during this treatment.
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  • 82
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    World journal of microbiology and biotechnology 11 (1995), S. 257-265 
    ISSN: 1573-0972
    Keywords: Biodegradation ; bioremediation ; cyanide, microorganisms ; toxic wastes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Many microorganisms have an inherent capacity to degrade the toxic organic compounds that enter the environment as a result of pollution and natural activities. Significant degradation of these compounds may take many years and it is frequently necessary to consider methods that can accelerate this process. There have been several demonstrations of enhanced biological degradation of toxic wastes, both in the laboratory and under field conditions. The prospects for enhanced biological cyanide degradation are reviewed. Compared with bench-scale processes, there are very few reports of field-scale processes for cyanide bioremediation. The implementation of such field-scale degradation requires inputs from biology, hydrology, geology, chemistry and civil engineering. A conceptual framework is emerging that can be adapted to develop new processes for bioremediation of toxic organic wastes. In terms of cyanide biodegradation, this framework incorporates identification of microbes, determination of the optimal conditions for degradation, establishment of the metabolic pathways involved in cyanide degradation, identification and localization of the genes involved, identification of suitable microbial strains for practical application and development of practical engineering processes. The present review addresses the progress that has been made in each of these aspects of cyanide biodegradation. It also examines the existing field applications of biological cyanide degradation and makes recommendations for future research.
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  • 83
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    World journal of microbiology and biotechnology 10 (1994), S. 472-474 
    ISSN: 1573-0972
    Keywords: Bacillus subtilis ; bioremediation ; copper ; Gram-positive walls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Purified cell walls from Bacillus subtilis were repeatedly suspended in 5 mm CuCl2 and, after removing unbound Cu, were suspended in 1% (v/v) HNO3 to release bound Cu. The walls were then regenerated by washing in H2O. After five cycles, copper binding actually increased slightly, probably due to enhanced exposure of binding sites in the walls. Thus bacterial walls may be used repeatedly for metal removal during bioremediation of heavy metal pollution.
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  • 84
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    Biotechnology and Bioengineering 43 (1994), S. 521-528 
    ISSN: 0006-3592
    Keywords: carbon tetrachloride ; acetate ; nitrate ; bioremediation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A denitrifying consortium capable of transforming carbon tetrachloride (CCl4) was cultured from aquifer sediment from the U.S. Department of Energy's Hanford Site in southeastern Washington State. To understand the kinetics of the biological destruction of CCl4 by these microbes, a set of experiments, the conditions of which were chosen according to a fractional factorial experimental design, were completed. This article reports on the experimental design along with the results for CCl4, biomass, acetate, nitrate, and nitrite concentrations. These data indicate that growth is inhibited by high nitrite concentrations, whereas CCl4 degradation is slowed by the presence of nitrate and/or nitrite. © 1994 John Wiley & Sons, Inc.
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  • 85
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    Applied Organometallic Chemistry 8 (1994), S. 501-508 
    ISSN: 0268-2605
    Keywords: Amendment ; biomethylation ; bioremediation ; dimethyl selenone ; headspace analysis ; fluorine-induced chemiluminescence ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A possible biological intermediate in the reduction and methylation of selenium oxyanions, dimethyl selenone, was synthesized, and the first experiments involving the amendment of selenium resistant bacterial cultures with this compound are reported. The amount of volatile, reduced selenium-containing species released from these cultures into the headspace is significantly more than that produced in analogous experiments involving sodium selenate amended cultures. Dimethyl selenone is reduced in the presence of dimethyl sulfide and dimethyl disulfide in a complex growth medium, trypticase soy broth with 0.1% nitrate. This reduction occurs whether or not the reduced sulfur compounds are biologically produced.
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  • 86
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    Journal of Chemical Technology AND Biotechnology 59 (1994), S. 9-23 
    ISSN: 0268-2575
    Keywords: microbial metabolism ; xenobiotics ; biodegradation ; bioremediation ; bioaugmentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The ability of microorganisms to metabolise xenobiotic compounds has received much attention due to the environmental persistence and toxicity of these chemicals. The microbial degradation of xenobiotics is seen as a cost effective method of removing these pollutants from the environment by a process now known as bioremediation. Microbial treatment of industrial effluents is also possible. Fundamental work has revealed that a wide variety of microorganisms are capable of degrading an equally wide range of organic pollutants. Pure and mixed cultures of microorganisms have been studied and degradation is observed under both aerobic and anaerobic conditions. Breakdown products have been found during work on the degradative pathways involved and toxicological assessments using bacteria and higher organisms (fish, plants) have been used to determine the toxicity of these intermediates. Many of the degradative genes responsible for xenobiotic metabolism are present on plasmids, transposons or are grouped in clusters on chromosomes. This provides clues to the evolution of degradative pathways and makes the task of genetic manipulation easier such that new microbial strains capable of efficiently degrading pollutants can be developed. Several enzymes involved in xenobiotic metabolism have been isolated and factors affecting their activity investigated. Genetically manipulated strains or naturally isolated organisms may be used in the treatment of industrial wastes or as inocula to enhance degradation in the environment. Environmental factors, including pH, temperature, bioavailability, nutrient supply and oxygen availability have been shown to affect xenobiotic biodegradation. These factors must be optimised to obtain a satisfactory microbial treatment process. Using information gained from fundamental research, bioremediation technology has been used to detoxify different contaminated environments and the results of field studies are very encouraging.
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  • 87
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    Biodegradation 4 (1993), S. 283-301 
    ISSN: 1572-9729
    Keywords: air pollution ; biofiltration ; bioremediation ; bioscrubbing ; off-gas treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper gives an overview of present biological techniques for the treatment of off-gases and the techniques that are being developed at the moment. The characteristics, advantages, disadvantages, costs and application area are discussed and compared. Biological off-gas treatment is based on the absorption of volatile contaminants in an aqueous phase or biofilm followed by oxidation by the action of microorganisms. Biofilters, bioscrubbers and biotrickling filters are used for elimination of odour and bioconvertable volatile organic and inorganic compounds and are enjoying increasing popularity. This popularity is a result of the low investment and operational costs involved compared to physico-chemical techniques and the elimination efficiencies that can be obtained. The operational envelop is still extending to higher concentrations and gas flow rates (exceeding 200,000 m3 h−1) and a broader spectrum of degradable compounds. Research and development on the use of membranes and the addition of activated carbon or a second liquid phase to the biological systems may lead to a more efficient elimination of hydrophobic compounds and buffering of fluctuating loads. Shorter adaptation periods can be obtained by inoculation with specialized microorganisms. Improved design and operation are made possible by the growing insights in the kinetics and microbiology and supported by the development of models describing biological off-gas treatment. In conclusion, biotechniques are efficient and cost effective in treating off-gases with concentrations of biodegradable contaminants up to 1–5 g/m3. They could play a justified and important role in air pollution control in the coming years.
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  • 88
    ISSN: 1573-5087
    Keywords: auxin ; Catharanthus roseus ; 2,4-dichlorophenoxyacetic acid (2,4-D) ; indole alkaloid ; protein synthesis ; two-dimensional polyacrylamide gel electrophoresis (2D-PAGE)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstracts Total and neosynthesized proteins of periwinkle cell suspensions (Catharanthus roseus) were first investigated in cells grown in a 2,4-D-containing medium. Analysis of total (silver-stained) proteins by two-dimensional gel electrophoresis revealed that the levels of seventeen polypeptides were altered during the growth cycle of the cells. Analysis of in vivo [35S]-methionine labeled polypeptides revealed differences in the synthesis of at least 35 polypeptides. Three polypeptides with molecular masses of 30, 35 and 39 kDa appeared to be specific markers of the early stationary phase. In a second sequence of experiments, cells were grown in a 2,4-D-free medium. Alterations in protein synthesis were observed: several polypeptides were expressed earlier in the 2,4-D-starved cells than in control cells; the synthesis of at least two specific polypeptides was increased in cells grown in 2,4-D-free medium, whereas the synthesis of three other polypeptides (molecular masses 33, 34 and 52.5 kDa) was switched on in these cells. As previous studies showed that 2,4-D depletion increased the alkaloid production in C. roseus cells, the present results may suggest that these polypeptides are implicated in the regulation of the alkaloid pathway.
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  • 89
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    Biodegradation 4 (1993), S. 231-240 
    ISSN: 1572-9729
    Keywords: bioremediation ; sediments ; Aroclor ; anaerobic microorganisms ; anaerobiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Reductive dechlorination is an advantageous process to microorganisms under anaerobic conditions because it is an electron sink, thereby allowing reoxidation of metabolic intermediates. In some organisms this has been demonstrated to support growth. Many chlorinated compounds have now been shown to be reductively dechlorinated under anaerobic conditions, including many of the congeners in commercial PCB mixtures. Anaerobic microbial communities in sediments dechlorinate Aroclor at rates of 3 µg Cl/g sediment × week. PCB dechlorination occurs at 12° C, a temperature relevant for remediation at temperate sites, and at concentrations of 100 to 1000 ppm. The positions dechlorinated are usually meta 〉 para 〉 ortho. The biphenyl rings, and the mono-ortho- and diorthochlorobiphenyls were not degraded after a one year incubation. Hence subsequent aerobic treatment may be necessary to meet regulatory standards. Reductive dechlorination of Arochlors does reduce their dioxin-like toxicity as measured by bioassay and by analysis of the co-planar congeners. The most important limitation to using PCB dechlorination as a remediation technology is the slower than desired dechlorination rates and no means yet discovered to substantially enhance these rates. Long term enrichments using PCBs as the only electron acceptor resulted in an initial enhancement in dechlorination rate. This rate was sustained but did not increase in serial transfers. Bioremediation of soil contaminated with Aroclor 1254 from a transformer spill was dechlorinated by greater than 50% following mixing of the soil with dechlorinating organisms and river sediment. It is now reasonable to field test reductive dechlorination of PCBs in cases where the PCB concentration is in the range where regulatory standards may be directly achieved by dechlorination, where a subsequent aerobic treatment is feasible, where any co-contaminants do not pose an inhibitory problem, and where anaerobic conditions can be established.
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  • 90
    ISSN: 1572-9729
    Keywords: aromatic hydrocarbons ; biodegradation ; bioremediation ; denitrification ; groundwater ; Pseudomonas
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We characterized bacteria from contaminated aquifers for their ability to utilize aromatic hydrocarbons under hypoxic (oxygen-limiting) conditions (initial dissolved oxygen concentration about 2 mg/l) with nitrate as an alternate electron acceptor. This is relevant to current intense efforts to establish favorable conditions forin situ bioremediation. Using samples of granular activated carbon slurries from an operating groundwater treatment system, we isolated bacteria that are able to use benzene, toluene, ethylbenzene, orp-xylene as their sole source of carbon under aerobic or hypoxic-denitrifying conditions. Direct isolation on solid medium incubated aerobically or hypoxically with the substrate supplied as vapor yielded 103 to 105 bacteria ml−1 of slurry supernatant, with numbers varying little with respect to isolation substrate or conditions. More than sixty bacterial isolates that varied in colony morphology were purified and characterized according to substrate utilization profiles and growth condition (i.e., aerobic vs. hypoxic) specificity. Strains with distinct characteristics were obtained using benzene compared with those isolated on toluene or ethylbenzene. In general, isolates obtained from direct selection on benzene minimal medium grew well under aerobic conditions but poorly under hypoxic conditions, whereas many ethylbenzene isolates grew well under both incubation conditions. We conclude that the conditions of isolation, rather than the substrate used, will influence the apparent characteristic substrate utilization range of the isolates obtained. Also, using an enrichment culture technique, we isolated a strain ofPseudomonas fluorescens, designated CFS215, which exhibited nitrate dependent degradation of aromatic hydrocarbons under hypoxic conditions.
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  • 91
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    Biotechnology and Bioengineering 41 (1993), S. 625-632 
    ISSN: 0006-3592
    Keywords: bioremediation ; biodegradation ; soil ; sorption/desorption ; intraparticle diffusion ; pollution ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: To determine when intraparticle diffusion and sorption can influence the rate of biodegradation, we consider the biodegradation of a pollutant diffusing into or out of porous aggregates suspended in a liquid medium, where the reactant is metabolized by bacteria. The pollutant that diffuses into the aggregates obeys a sorption-desorption equilibrium isotherm at sites on inner pore surfaces. The governing partial differential equations for the transient process describe (a) the local equilibrium sorption-desorption and the diffusion of the pollutant in the porous aggregate, (b) the mass transfer of the pollutant from the external surface of the spherical aggregates to the reaction medium, and (c) the biodegradation of the pollutant in the external medium. Illustrative calculations are presented for a linear sorption calculations are presented for a linear sorption isotherm and first-order biodegradation kinetics. A dimensionless group, comprised of the diffusion coefficient, biodegradation rate coefficient, aggregate characteristics length (radius), and adsorption capacity, serves as a criterion for determining when intraparticle diffusion can be ignored. The model provides a realistic description of experimental data for biodegradation of a pollutant subject to intraparticle diffusion and sorption. © 1993 John Wiley & Sons, Inc.
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  • 92
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    Biodegradation 3 (1992), S. 161-170 
    ISSN: 1572-9729
    Keywords: bioremediation ; cadmium ; heavy metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Cadmium pollution arises mainly from contamination of minerals used in agriculture and from industrial processes. The usual situation is of large volumes of soil and water that are contaminated with low — but significant — concentrations of cadmium. Therefore, detoxification of the polluted water and soil involves the concentration of the metal, or binding it in a way that makes it biologically inert. Cadmium is one of the more toxic metals, that is also carcinogenic and teratogenic. Its effects are short term, even acute (diseases like Itai-itai), or long term. The long term effects are intensified due to the fact that cadmium accumulates in the body. This paper describes a study involving several hundred cadmium-resistant bacterial isolates. These bacteria could be divided into three groups—the largest group consisted of bacteria resistant to cadmium by effluxing it from the cells. The bacteria of the other two groups were capable of binding cadmium or of detoxifying it. We concentrated on one strain that could bind cadmium very efficiently, depending on the bacterial biomass and on the pH. This strain could effectively remove cadmium from contaminated water and soil.
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  • 93
    ISSN: 1572-9729
    Keywords: petroleum ; bioremediation ; hydrocarbon pollution ; bioemulsifiers ; petroleum microbiology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Microbial degradation of hydrocarbons is a multiphase reaction, involving oxygen gas, water-insoluble hydrocarbons, water, dissolved salts and microorganisms. The fact that the first step in hydrocarbon catabolism involves a membrane-bound oxygenase makes it essential for microorganisms to come into direct contact with the hydrocarbon substrate. Growth then proceeds on the hydrocarbon/water interface. Bacteria have developed two general strategies for enhancing contact with water-insoluble hydrocarbons: specific adhesion mechanisms and production of extracellular emulsifying agents. Since petroleum is a complex mixture of many different classes of hydrocarbons, of which any particular microorganism has the potential to degrade only part, it follows that the microorganisms must also have a mechanism for desorbing from used' oil droplets. The major limitations in bioremediation of hydrocarbon-contaminated water and soil is available sources of nitrogen and phosphorus. The usual sources of these materials, e.g. ammonium sulfate and phosphate salts, have a high water solubility which reduces their effectiveness in open systems because of rapid dilution. We have attempted to overcome this problem by the use of a new controlled-release, hydrophobic fertilizer, F-1, which is a modified urea-formaldehyde polymer containing 18% N and 10% P as P2O5. Microorganisms were obtained by enrichment culture that could grow on crude oil as the carbon and energy source and F-1 as the nitrogen and phosphorus source. The microorganisms and the F-1 adhered to the oil/water interface, as observed microscopically and by the fact that degradation proceeded even when the water phase was removed and replaced seven times with unsupplemented water — a simulated open system. Strains which can use F-1 contain a cell-bound, inducible enzyme which depolymerizes F-1. After optimizing conditions in the laboratory for the use of F-1 and the selected bacteria for degrading crude oil, a field trial was performed on an oil contaminated sandy beach between Haifa and Acre, Israel, in the summer of 1992. The sand was treated with 5 g F-1 per kg sand and inoculated with the selected bacteria; the plot was watered with sea water and plowed daily. After 28 days the average hydrocarbon content of the sand decreased from 5.1 mg per g sand to 0.6 mg per g sand. Overall, there was an approx. 86% degradation of pentane extractables as demonstrated by dry weight, I.R. and GLC analyses. An untreated control plot showed only a 15% decrease in hydrocarbons. During the winter of 1992, the entire beach (approx. 200 tons of crude oil) was cleaned using the F-1 bacteria technology. The rate of degradation was 0.06 mg g-1 sand day-1 (10°C) compared to 0.13 mg g-1 sand day-1 during the summer (25°C).
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  • 94
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    Journal of aquatic ecosystem stress and recovery 1 (1992), S. 253-262 
    ISSN: 1573-5141
    Keywords: bacteria ; factor analysis ; path analysis ; aquatic ; gene probe ; bioremediation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Studies on aquatic ecosystems at the trophic level of bacteria include population succession and the movement of species through the water column. Factor and path analysis of environmental parameters and the bacterial profiles indicate that the bacterial populations are under the control of environmental factors. The most important environmental factors in the Canadian study reported here are temperature followed by oxygen levels, nutrient levels, and ion concentrations. A major revolution in investigative approaches has begun in aquatic bacterial population studies using technology based on molecular methods. Finger print analysis of bacterial 16S RNA (molecular phylogeny) has not only changed the classification of bacteria but also the approach to solving environmental problems. The bacterial groups have been placed into species that are more functionally and ecologically aligned. Uncultured mixed biomass can be examined by gene probes for both procaryotes and eucaryotes to identify specific nucleotide sequences. Aquatic ecosystem health is maintained by the balanced biota and the process of biodegradation is an important stage in bioremediation. Control of toxic wasters in the waters and groundwaters can be accomplished byin situ bioremediation using indigenous microorganisms as demonstrated by the field study reported by Litchfieldet al. (1990).
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  • 95
    ISSN: 1572-9729
    Keywords: bioremediation ; inorganic mercury ; organomercury
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Bacterially mediated ionic mercury reduction to volatile Hg0 was shown to play an important role in the geochemical cycling of mercury in a contaminated freshwater pond. This process, and the degradation of methylmercury, could be stimulated to reduce the concentration of methylmercury that is available for accumulation by biota. A study testing the utility of this approach is described.
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  • 96
    ISSN: 1572-9729
    Keywords: hydrocarbon biodegradation ; bioassay ; radiorespirometry ; bioremediation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Following the EXXOn Valdez oil spill, a radiorespirometric protocol was developed at the University of Alaska Fairbanks (UAF) to assess the potential for microorganisms in coastal waters and sediments to degrade hydrocarbons. The use of bioremediation to assist in oil spill cleanup operations required microbial bioassays to establish that addition of nitrogen and phosphorus would enhance biodegradation. A technique assessing 1-14C-n-hexadecane mineralization in seawater or nutrient rich sediment suspensions was used for both of these measurements. Hydrocarbon-degradation potentials were determined by measuring mineralization associated with sediment microorganisms in sediment suspended in sterilized seawater and/or marine Bushnell-Haas broth. Production of 14CO2 and CO2 was easily detectable during the first 48 hours with added hexadecane levels ranging from 10 to 500 mg/l of suspension and dependent on the biomass of hydrocarbon degraders, the hydrocarbon-oxidation potential of the biomass and nutrient availability. In addition to assessment of the hydrocarbon-degrading potential of environmental samples, the radiorespirometric procedure, and concomitant measurement of microbial biomass, has utility as an indicator of hydrocarbon contamination of soils, aqueous sediments and water, and can also be used to evaluate the effectiveness of bioremediation treatments.
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  • 97
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    New forests 5 (1991), S. 359-367 
    ISSN: 1573-5095
    Keywords: indole-3-butyric acid (IBA) ; 2,4-dichlorophenoxyacetic acid (2,4-D) ; bareroot seedlings ; root development ; root dip ; Pinus ponderosa (Dougl. ex Laws.) ; Celtis occidentalis (L.) ; hygroscopic gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Greenhouse and field studies were conducted to determine the effects of indole3-butyric acid (IBA) and 2,4-dichlorophenoxyacetic acid (2,4-D) on root development and survival of 3+0 bareroot Pinus ponderosa (Dougl. ex Laws.) and 2+0 bareroot Celtis occidentalis (L) seedlings. In the greenhouse, 100 and 200 ppm. IBA and 10 and 50 ppm 2,4-D were applied to seedlings through a root dip in an auxin hygroscopic gel mix. A randomized complete block analysis of variance indicated that IBA gel treatments increased root volume and root dry weight in hackberry and had no effect on ponderosa pine; 2,4-D gel treatments had detrimental effects on both species. In the field, IBA gel treated ponderosa pine seedlings exhibited improved height and survival relative to the non-treated control seedlings. There was no detectable improvement in survival in the field for hackberry. However, diameter and stem dry weight were lower for hackberry seedlings treated with the gel dip alone.
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  • 98
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    Biodegradation 1 (1990), S. 283-290 
    ISSN: 1572-9729
    Keywords: bioremediation ; metabolites ; microbial degradation ; naphthalene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A Mycobacterium sp. isolated from oil-contaminated sediments was previously shown to mineralize 55% of the added naphthalene to carbon dioxide after 7 days of incubation. In this paper, we report the initial steps of the degradation of naphthalene by a Mycobacterium sp. as determined by isolation of metabolites and incorporation of oxygen from 18O2 into the metabolites. The results indicate that naphthalene is initially converted to cis- and trans-1,2-dihydroxy-1,2-dihydronaphthalene by dioxygenase and monooxygenase catalyzed reactions, respectively. The ratio of the cis to trans-naphthalene dihydrodiol isomers was approximately 25:1. Thin layer and high pressure liquid chromatographic and mass spectrometric techniques indicated that besides the cis- and trans-1,2-dihydroxy-1,2-dihydronaphthalene, minor amounts of ring cleavage products salicylate and catechol were also formed. Thus the formation of both cis and trans-naphthalene dihydrodiols by the Mycobacterium sp. is unique. The down-stream reactions to ring cleavage products proceed through analogous dioxygenase reactions previously reported for the bacterial degradation of naphthalene.
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  • 99
    ISSN: 1573-5028
    Keywords: 2,4-dichlorophenoxyacetic acid (2,4-D) ; detoxification ; herbicide resistance ; transgenic plants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Plants resistant to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) were produced through the genetic engineering of a novel detoxification pathway into the cells of a species normally sensitive to 2,4-D. We cloned the gene for 2,4-D monooxygenase, the first enzyme in the plasmid-encoded 2,4-D degradative pathway of the bacterium Alcaligenes eutrophus, into a cauliflower mosaic virus 35S promoter expression vector and introduced it into tobacco plants by Agrobacterium-mediated transformation. Transgenic tobacco plants expressing the highest levels of the monooxygenase enzyme exhibited increased tolerance to 2,4-D in leaf disc and seed germination assays, and young plants survived spraying with levels of herbicide up to eight times the usual field application rate. The introduction of the gene for 2,4-D monooxygenase into broad-leaved crop plants, such as cotton, should eventually allow 2,4-D to be used as an inexpensive post-emergence herbicide on economically important dicot crops.
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  • 100
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    Applied Organometallic Chemistry 2 (1988), S. 159-169 
    ISSN: 0268-2605
    Keywords: Arsenic ; bacteria ; bioremediation ; energy residuals ; fungi ; organoarsenic compounds ; retorted shale ; soil ; volatilization ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nutrient effects on microbial growth and arsenic volatilization from retorted oil shale and soil were evaluated in a laboratory study. Dimethylarsinic acid (DMAA), methanearsonic acid (MAA) and sodium arsenate amendments were used with added nutrients, or with retort process water added to simulate possible co-disposal conditions. In experiments with soil and retorted shale, dimethylarsinic acid showing the highest cumulative arsenic releases, in comparison with added inorganic sodium arsenate (SA). Low but detectable amounts of innate arsenic present in retorted shale could be volatilized with added organic matter. In soil, arsenic volatilization showed a direct relationship to nutrient levels and microbial growth. With shale, in comparison, a threshold response to available nutrients was evident. Distinct increases in fungal community development occurred with nutrients available at a level of 2.5% w/v, which also allowed incresed arsenic volatization. Codisposal of retort process waters with shale allowed arsenic volatilization without the addition of other nutrients. The presence of retort process water limited arsenic volatilization from the added organometallic compounds DMAA and MAA, but not from SA or innate arsenic. These differences should be useful in the definition of permissive and non-permissive environmental conditions for arsenic volatilization in bioremediation programs.
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