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  • 1
    ISSN: 1432-0789
    Keywords: Key words Benzoate biodegradation ; Comamonas terrigena ; Denitrification ; Interfacial environment ; Redox potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The purpose of this work was to assess the influence of redox conditions on benzoate biodegradation coupled with oxygen and nitrate as electron acceptors. A benzoate-degrading, facultatively denitrifying bacterium was isolated from a sediment sample and was tentatively identified as Comamonas terrigena (strain J92-6). The experimental system was based on sand columns that were filled with liquid medium containing benzoate and nitrate. The columns were inoculated to provide a fixed biofilm on the sand. Conditions were created by aeration, dinitrogen-purging, and sodium sulfide amendment that comprised oxic, anoxic, and reduced (–375 mV) zones, respectively, at different depths of the columns. Anaerobic biodegradation of benzoate was nitrate-dependent and proceeded at all redox potential values ranging from +400 to –375 mV. Thus, benzoate degradation coupled with denitrification was not inhibited at low redox potentials characteristic of sulfate reduction and methanogenesis. The results demonstrate that the fixed biofilm column system can be successfully used to evaluate the influence of environmental factors on the biodegradation of benzoate, a central decomposition product of anaerobic, aromatic hydrocarbon biodegradation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 27 (1998), S. 79-84 
    ISSN: 1432-0789
    Keywords: Key words Soil microflora ; Earthworm ; Soil biotic interactions ; CO2 release ; Protozoa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  The stimulatory effect of earthworms (Lumbricus terrestris L.) on soil microbial activity was studied under microcosm-controlled conditions. The hypothesis was tested that microbial stimulation observed in the presence of a soil invertebrate would be due to the utilization of additional nutritive substances (secretion and excretion products) that it provides. Changes in microbial activity were monitored by measuring simultaneously CO2 release and protozoan population density. The increase in CO2 released in the presence of earthworms was found to result from both earthworm respiration and enhanced microbial respiration. The stimulation of microbial activity was confirmed by a significant increase in protozoan population density, which was 3–19 times greater in the presence of earthworms. The respiratory rate of L. terrestris was estimated to be 53 μl O2 g–1 h–1. Earthworm respiration significantly correlated with individual earthworm weight, but there was no correlation between the increase in microbial respiration and earthworm weight. This finding does not support the hypothesis given above that enhanced microbial respiration is due to utilization of earthworm excreta. A new hypothesis that relationships between microbial activity and earthworms are not based on trophic links alone but also on catalytic mechanisms is proposed and discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied microbiology and biotechnology 49 (1998), S. 618-623 
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Anaerobic biodegradation of atrazine by the bacterial isolate M91-3 was characterized with respect to mineralization, metabolite formation, and denitrification. The ability of the isolate to enhance atrazine biodegradation in anaerobic sediment slurries was also investigated. The organism utilized atrazine as its sole source of carbon and nitrogen under anoxic conditions in fixed-film (glass beads) batch column systems. Results of HPLC and TLC radiochromatography suggested that anaerobic biotransformation of atrazine by microbial isolate M91-3 involved hydroxyatrazine formation. Ring cleavage was demonstrated by 14CO2 evolution. Denitrification was confirmed by detection of 15N2 in headspace samples of K15NO3-amended anaerobic liquid cultures. In aquatic sediments, mineralization of uniformly ring-labeled [14C]atrazine occurred in both M91-3-inoculated and uninoculated sediment. Inoculation of sediments with M91-3 did not significantly enhance anaerobic mineralization of atrazine as compared to uninoculated sediment, which suggests the presence of indigenous organisms capable of anaerobic atrazine biodegradation. Results of this study suggest that the use of M91-3 in a fixed-film bioreactor may have applications in the anaerobic removal of atrazine and nitrate from aqueous media.
    Type of Medium: Electronic Resource
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