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  • 2005-2009  (4)
  • 1990-1994  (18)
  • 2,4-dichlorophenoxyacetic acid (2,4-D)
  • DGGE
  • bioremediation
  • 1
    Digitale Medien
    Digitale Medien
    Anaerobic Bioremediation of Groundwater Containing a Mixture of 1,1,2,2-Tetrachloroethane and Chloroethenes (2006)
    Springer
    Biodegradation 17 (2006), S. 193-206 
    Details
    ISSN: 1572-9729
    Schlagwort(e): bioremediation ; Dehalococcoides ; dechlorination ; microcosm ; tetrachloroethane ; trichloroethene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s10532-005-4218-7
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  • 2
    Digitale Medien
    Digitale Medien
    2,4-Dichlorophenoxyacetic Acid (2,4-D) Utilization by Delftia acidovorans MC1 at Alkaline pH and in the Presence of Dichlorprop is Improved by Introduction of the tfdK Gene (2006)
    Springer
    Biodegradation 17 (2006), S. 263-273 
    Details
    ISSN: 1572-9729
    Schlagwort(e): 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
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s10532-005-6894-8
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  • 3
    Digitale Medien
    Digitale Medien
    The Impact of Bioaugmentation on Metal Cyanide Degradation and Soil Bacteria Community Structure (2006)
    Springer
    Biodegradation 17 (2006), S. 207-217 
    Details
    ISSN: 1572-9729
    Schlagwort(e): biodegradation ; DGGE ; K2Ni(CN)4 soil bacterial populations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Metal cyanides are significant contaminants of many soils found at the site of former industrial activity. In this study we isolated bacteria capable of degrading ferric ferrocyanide and K2Ni(CN)4. One of these bacteria a Rhodococcus spp. was subsequently used to bioaugment a minimal medium broth, spiked with K2Ni(CN)4, containing 1 g of either an uncontaminated topsoil or a former coke works site soil. Degradation of the K2Ni(CN)4 was observed in both soils, however, bioaugmentation did not significantly impact the rate or degree of K2Ni(CN)4 removal. Statistical analysis of denaturing gradient gel electrophoresis profiles showed that the topsoil bacterial community had a higher biodiversity, and its structure was not significantly affected by either K2Ni(CN)4 or bioaugmentation. In contrast, profiles from the coke works site indicated significant changes in the bacterial community in response to these additions. Moreover, in both soils although bioaugmentation did not affect rates of biodegradation the Rhodococcus spp. did become established in the communities in broths containing both top and coke works soil. We conclude that bacterial communities from contaminated soils with low biodiversity are much more readily perturbed through interventions such as contamination events or bioaugmentation treatments and discuss the implications of these findings for bioremediation studies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s10532-005-4219-6
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  • 4
    Digitale Medien
    Digitale Medien
    Bioremediation by Composting of Heavy Oil Refinery Sludge in Semiarid Conditions (2006)
    Springer
    Biodegradation 17 (2006), S. 251-261 
    Details
    ISSN: 1572-9729
    Schlagwort(e): bioremediation ; composting ; ecotoxicity ; oil sludge
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s10532-005-5020-2
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  • 5
    Digitale Medien
    Digitale Medien
    Repeated use of Bacillus subtilis cell walls for copper binding (1994)
    Springer
    World journal of microbiology and biotechnology 10 (1994), S. 472-474 
    Details
    ISSN: 1573-0972
    Schlagwort(e): Bacillus subtilis ; bioremediation ; copper ; Gram-positive walls
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00144475
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  • 6
    Digitale Medien
    Digitale Medien
    Biological destruction of CCl4: I. Experimental design and data (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 521-528 
    Details
    ISSN: 0006-3592
    Schlagwort(e): carbon tetrachloride ; acetate ; nitrate ; bioremediation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: 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.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260430613
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  • 7
    Digitale Medien
    Digitale Medien
    Amending cultures of selenium-resistant bacteria with dimethyl selenone (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 8 (1994), S. 501-508 
    Details
    ISSN: 0268-2605
    Schlagwort(e): Amendment ; biomethylation ; bioremediation ; dimethyl selenone ; headspace analysis ; fluorine-induced chemiluminescence ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/aoc.590080602
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  • 8
    Digitale Medien
    Digitale Medien
    Microbial metabolism of xenobiotics: Fundamental and applied research (1994)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 59 (1994), S. 9-23 
    Details
    ISSN: 0268-2575
    Schlagwort(e): microbial metabolism ; xenobiotics ; biodegradation ; bioremediation ; bioaugmentation ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: 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.
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jctb.280590104
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  • 9
    Digitale Medien
    Digitale Medien
    Biotechniques for air pollution control (1993)
    Springer
    Biodegradation 4 (1993), S. 283-301 
    Details
    ISSN: 1572-9729
    Schlagwort(e): air pollution ; biofiltration ; bioremediation ; bioscrubbing ; off-gas treatment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00695975
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  • 10
    Digitale Medien
    Digitale Medien
    Effects of 2,4-D removal on the synthesis of specific proteins by Catharanthus roseus cell cultures (1993)
    Springer
    Plant growth regulation 13 (1993), S. 287-295 
    Details
    ISSN: 1573-5087
    Schlagwort(e): auxin ; Catharanthus roseus ; 2,4-dichlorophenoxyacetic acid (2,4-D) ; indole alkaloid ; protein synthesis ; two-dimensional polyacrylamide gel electrophoresis (2D-PAGE)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00024850
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  • 11
    Digitale Medien
    Digitale Medien
    Microbial reductive dechlorination of PCBs (1993)
    Springer
    Biodegradation 4 (1993), S. 231-240 
    Details
    ISSN: 1572-9729
    Schlagwort(e): bioremediation ; sediments ; Aroclor ; anaerobic microorganisms ; anaerobiosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00695971
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  • 12
    Digitale Medien
    Digitale Medien
    Metabolic diversity of aromatic hydrocarbon-degrading bacteria from a petroleum-contaminated aquifer (1993)
    Springer
    Biodegradation 4 (1993), S. 249-259 
    Details
    ISSN: 1572-9729
    Schlagwort(e): aromatic hydrocarbons ; biodegradation ; bioremediation ; denitrification ; groundwater ; Pseudomonas
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00695973
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  • 13
    Digitale Medien
    Digitale Medien
    Criteria to assess when biodegradation is kinetically limited by intraparticle diffusion and sorption (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 41 (1993), S. 625-632 
    Details
    ISSN: 0006-3592
    Schlagwort(e): bioremediation ; biodegradation ; soil ; sorption/desorption ; intraparticle diffusion ; pollution ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: 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.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/bit.260410605
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  • 14
    Digitale Medien
    Digitale Medien
    Interactions of bacteria with cadmium (1992)
    Springer
    Biodegradation 3 (1992), S. 161-170 
    Details
    ISSN: 1572-9729
    Schlagwort(e): bioremediation ; cadmium ; heavy metals
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00129081
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  • 15
    Digitale Medien
    Digitale Medien
    Petroleum bioremediation — a multiphase problem (1992)
    Springer
    Biodegradation 3 (1992), S. 337-350 
    Details
    ISSN: 1572-9729
    Schlagwort(e): petroleum ; bioremediation ; hydrocarbon pollution ; bioemulsifiers ; petroleum microbiology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00129092
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  • 16
    Digitale Medien
    Digitale Medien
    Rapid molecular characterization of mutations leading to unstable hemoglobin β-chain variants (1992)
    Springer
    Annals of hematology 65 (1992), S. 188-192 
    Details
    ISSN: 1432-0584
    Schlagwort(e): β-globin ; Unstable hemoglobins ; Polymerase chain reaction ; DGGE
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Characterization of unstable hemoglobins by protein analysis is often difficult. However, it is facilitated by DNA analysis, especially in the case of hyperunstable β-chain variants, which produce a β-thalassemia phenotype. We have applied an efficient strategy to the detection of such variants at the DNA level, based on computer-designed denaturing gradient gel electrophoresis (DGGE) of amplified DNA fragments. This approach makes it possible to detect any anomaly in the β-globin gene. We describe the use of the DGGE method for rapid characterization of β-chain variants and report a new missense mutation in the β-globin gene third exon, β 127 CAG-CGG/Gln-Arg, which is responsible for the synthesis of a highly unstable hemoglobin.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01703113
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  • 17
    Digitale Medien
    Digitale Medien
    Detection of DNA sequence polymorphisms among wheat varieties (1992)
    Springer
    Theoretical and applied genetics 84 (1992), S. 573-578 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Common wheat ; RAPD ; DGGE ; DNA polymorphism ; DNA markers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A DNA marker detection strategy that allows the rapid, efficient resolution of high levels of polymorphism among closely related lines of common wheat (Triticum aestivum) has been developed to circumvent the apparent lack of restriction fragment length polymorphism in many important self-pollinated crop species. The technique of randomly amplified polymorphic DNA (RAPD) was combined with a denaturing gradient gel electrophoresis system (DGGE) to explore DNA sequence polymorphisms among different genotypes of wheat. Of the 65 primer combinations used for the polymerase chain reaction (PCR) amplifications, over 38% of them produced readily detectable and reproducible DNA polymorphisms between a spring wheat line, SO852, and a winter wheat variety, ‘Clark’. A high level of polymorphism was observed among a number of commercial varieties and breeding lines of wheat. This procedure was also used to detect polymorphisms in a recombinant inbred population to test the feasibility of its application in genome mapping. This DNA polymorphism detection system provides an opportunity for pedigree analysis and fingerprinting of developed wheat lines as well as construction of a high density genetic map of wheat. Without the need for 32P and sophisticated DNA extraction procedures, this approach should make it feasible to utilize marker-based selection in a plant breeding program.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00224154
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  • 18
    Digitale Medien
    Digitale Medien
    Aquatic microorganisms: processes, populations, and molecular solutions to environmental problems (1992)
    Springer
    Journal of aquatic ecosystem stress and recovery 1 (1992), S. 253-262 
    Details
    ISSN: 1573-5141
    Schlagwort(e): bacteria ; factor analysis ; path analysis ; aquatic ; gene probe ; bioremediation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: 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).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00044167
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  • 19
    Digitale Medien
    Digitale Medien
    Mercury biotransformations and their potential for remediation of mercury contamination (1992)
    Springer
    Biodegradation 3 (1992), S. 147-159 
    Details
    ISSN: 1572-9729
    Schlagwort(e): bioremediation ; inorganic mercury ; organomercury
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00129080
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  • 20
    Digitale Medien
    Digitale Medien
    UAF radiorespirometric protocol for assessing hydrocarbon mineralization potential in environmental samples (1991)
    Springer
    Biodegradation 2 (1991), S. 121-127 
    Details
    ISSN: 1572-9729
    Schlagwort(e): hydrocarbon biodegradation ; bioassay ; radiorespirometry ; bioremediation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00114602
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  • 21
    Digitale Medien
    Digitale Medien
    Auxin-impregnated hygroscopic gel: effects on ponderosa pine and common hackberry seedlings (1991)
    Springer
    New forests 5 (1991), S. 359-367 
    Details
    ISSN: 1573-5095
    Schlagwort(e): 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
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00118863
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  • 22
    Digitale Medien
    Digitale Medien
    Identification of metabolites from degradation of naphthalene by a Mycobacterium sp. (1990)
    Springer
    Biodegradation 1 (1990), S. 283-290 
    Details
    ISSN: 1572-9729
    Schlagwort(e): bioremediation ; metabolites ; microbial degradation ; naphthalene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00119765
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