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Substantially Enhanced Degradation of Hexachlorocyclohexane Isomers by a Microbial Consortium on Acclimation.

Daniel Elcey, C. and Mohammad Kunhi, A. A. (2010) Substantially Enhanced Degradation of Hexachlorocyclohexane Isomers by a Microbial Consortium on Acclimation. Journal of Agricultural and Food Chemistry , 58. pp. 1046-1054.

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Abstract

Widespread contamination of the environment, globally, has been caused by extensive and indiscriminate use of hexachlorocyclohexane (HCH) as an insecticide since the 1940s, threatening the biota including humans, and there is an urgent need to eliminate it, preferably through bioremediation technologies. A γ-HCH-degrading microbial consortium was isolated by enrichment of a soil sample from a sugar cane field having a long history of technical grade HCH application. On acclimation the degrading ability improved substantially. The consortium, which took 10 days to degrade 25 μg mL-1 of γ-HCH, initially could mineralize even 300 μg mL-1 of the substrate within 108 h on acclimation. With 300 μg mL-1 substrate, the rate of degradation, as calculated for the early exponential phase, was 216 μg mL-1 day-1, the highest reported so far. An amount of 400 μg mL-1 of γ-HCH, however, was mineralized partially with only 78% Cl- release. No apparent accumulation of intermediary metabolites was observed up to 300 μg mL-1 substrate, indicating a fast rate of mineralization. Aeration, mesophilic temperatures (20-35 �C), and near neutral pH (6.0-8.0) were favorable conditions for degradation. The presence of glucose at 1000 μg mL-1 retarded the degradation, whereas cellulose and sawdust at 1600 μg mL-1 and glucose at 100 μg mL-1 did not show any marked effect. The consortium also mineralized R-, β-, and δ-HCH efficiently. The consortium consisted of nine bacterial strains and a fungal strain, and individually they were able to degrade 10 μg mL-1 of γ-HCH. This mixed culture holds high potential for deployment in bioremediation of HCH-contaminated soils, waste dumpsites, and water bodies.

Item Type: Article
Uncontrolled Keywords: Hexachlorocyclohexane; microbial consortium; acclimation; enhanced mineralization; environmental factors
Subjects: 500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 26 Pesticide Chemistry
500 Natural Sciences and Mathematics > 07 Life Sciences > 04 Microbiology
Divisions: Food Microbiology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 21 Jul 2011 04:44
Last Modified: 28 Dec 2011 10:26
URI: http://ir.cftri.com/id/eprint/10300

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