Enhanced biodegradation of beta- and delta-hexachlorocyclohexane in the presence of alpha- and gamma-isomers in contaminated soils.
The chlorinated insecticide hexachlorocyclohexane (HCH) has been used extensively in the past, and contaminated sites are present throughout the world. Toward their bioremediation, we isolated a bacterium Pseudomonas aeruginosa ITRC-5 that mediates the degradation of all the four major isomers of HCH under aerobic conditions, both in liquid-culture and contaminated soils. In liquid-culture, the degradation of alpha- and gamma-HCH is rapid and is accompanied with the release of 5.6 micromole chloride ions and 4.1 micromole CO2 micromole(-1) HCH-isomer. The degradation of beta- and delta-isomers is slow, accompanied with the release of 0.9 micromole chloride ions micromole(-1) HCH-isomer, and results in a transient metabolite 2,3,4,5,6-pentachlorocyclohexan-1-ol. The strain ITRC-5 also mediates the degradation of alpha-, beta-, gamma-, and delta-isomers in contaminated soils, where degradation of otherwise persistent beta- and delta-HCH is enhanced severalfold in the presence of alpha- or gamma-HCH. The degradation of soil-applied beta- and delta-HCH under aerobic conditions has not been reported earlier. The isolate ITRC-5 therefore demonstrates potential for the bioremediation of HCH-wastes and contaminated soils.
Industrial Toxicology Research Centre, Post Box No 80, Mahatma Gandhi Marg, Lucknow-226 001, India.
Manish
M
Kumar
Pankaj
P
Chaudhary
Manish
M
Dwivedi
Ranjan
R
Kumar
Debarati
D
Paul
Rakesh K
RK
Jain
Satyendra K
SK
Garg
Ashwani
A
Kumar
D000332:Aerobiosis; D001673:Biodegradation, Environmental / Q000187:drug effects; D001711:Biotransformation; D002245:Carbon Dioxide / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D001556:Hexachlorocyclohexane / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D007477:Ions; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D012989:Soil Pollutants / Q000378:metabolism*; D013997:Time Factors
D002712:Chlorides; D007477:Ions; D012989:Soil Pollutants; D002245:Carbon Dioxide; C010275:pentachlorocyclohexene; C040534:alpha-hexachlorocyclohexane; C086916:delta-hexachlorocyclohexane; D001556:Hexachlorocyclohexane; C023888:beta-hexachlorocyclohexane