Biological reductive dechlorination of tetrachloroethylene and trichloroethylene to ethylene under methanogenic conditions.
A biological process for remediation of groundwater contaminated with tetrachloroethylene (PCE) and trichloroethylene (TCE) can only be applied if the transformation products are environmentally acceptable. Studies with enrichment cultures of PCE- and TCE-degrading microorganisms provide evidence that, under methanogenic conditions, mixed cultures are able to completely dechlorinate PCE and TCE to ethylene, a product which is environmentally acceptable. Radiotracer studies with [14C]PCE indicated that [14C]ethylene was the terminal product; significant conversion to 14CO2 or 14CH4 was not observed. The rate-limiting step in the pathway appeared to be conversion of vinyl chloride to ethylene. To sustain reductive dechlorination of PCE and TCE, it was necessary to supply an electron donor; methanol was the most effective, although hydrogen, formate, acetate, and glucose also served. Studies with the inhibitor 2-bromoethanesulfonate suggested that methanogens played a key role in the observed biotransformations of PCE and TCE.
Freedman
D L
DL
School of Civil and Environmental Engineering, Cornell University, Ithaca, New York 14853-3501.
Gossett
J M
JM
D000476:Alkanesulfonates / Q000494:pharmacology; D017738:Alkanesulfonic Acids; D001673:Biodegradation, Environmental / Q000187:drug effects; D004579:Electron Transport; D005030:Ethylenes; D019605:Euryarchaeota / Q000378:metabolism*; D008697:Methane / Q000378:metabolism*; D010084:Oxidation-Reduction; D013750:Tetrachloroethylene / Q000378:metabolism*; D014241:Trichloroethylene / Q000378:metabolism*; D014873:Water Pollutants / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
D000476:Alkanesulfonates; D017738:Alkanesulfonic Acids; D005030:Ethylenes; D014873:Water Pollutants; D014874:Water Pollutants, Chemical; C012210:BES; D014241:Trichloroethylene; C036216:ethylene; D008697:Methane; D013750:Tetrachloroethylene