1,1-dichloroethene as a predominant intermediate of microbial trichloroethene reduction.
A microbial culture derived from a landfill site in Dover, DE consistently reduced trichloroethene (TCE) to ethene through 1,1-dichloroethene (DCE) as a dominant intermediate in the presence of ampicillin. A constant 1,1-DCE-to-cis-DCE ratio of 2.4 +/- 0.3 was observed for more than two years, while trans-DCE was never detected. Without ampicillin, however, TCE was reduced to ethene almost exclusively through cis-DCE, suggesting that the culture contained at leasttwo TCE-dechlorinating populations. Two subcultures, which were established using 1,1-DCE or vinyl chloride as an electron acceptor, exhibited the same 1,1-DCE-to-cis-DCE ratio when TCE was introduced. PCR amplification of 16S rRNA gene followed by sequencing and DGGE analysis indicate that these (sub)cultures contained a Dehalococcoides population(s). TCE dechlorination assays with crude cell extract showed a DCE distribution pattern similar to that with whole cells. The enzyme involved in 1,1-DCE formation was likely a cobalt corrinoid enzyme, as suggested by the inhibitory effect of CH3I and photoreversibility of the inhibition. This study provides a possible biological mechanism forthe occurrence of 1,1-DCE in TCE-contaminated sites.
Department of Civil and Environmental Engineering, University of Delaware, Newark, Delaware 19716, USA.
Jingling
J
Zhang
Andrew P
AP
Joslyn
Pei C
PC
Chiu
D000667:Ampicillin / Q000494:pharmacology; D001673:Biodegradation, Environmental; D002713:Chlorine / Q000737:chemistry / Q000378:metabolism; D041862:Chloroflexi / Q000302:isolation & purification / Q000378:metabolism; D003035:Cobalt / Q000378:metabolism; D045728:Corrinoids / Q000378:metabolism; D004000:Dichloroethylenes / Q000032:analysis / Q000378:metabolism*; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry* / Q000382:microbiology*; D006847:Hydrocarbons, Iodinated / Q000494:pharmacology; D010084:Oxidation-Reduction; D010777:Photochemistry; D016133:Polymerase Chain Reaction / Q000379:methods; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D013237:Stereoisomerism; D013997:Time Factors; D014241:Trichloroethylene / Q000032:analysis / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000378:metabolism*
D045728:Corrinoids; D004000:Dichloroethylenes; D006847:Hydrocarbons, Iodinated; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; C029297:vinylidene chloride; D014241:Trichloroethylene; D003035:Cobalt; D002713:Chlorine; D000667:Ampicillin; C014055:methyl iodide