Stereoselective microbial dehalorespiration with vicinal dichlorinated alkanes.
The suspected carcinogen 1,2-dichloroethane (1,2-DCA) is the most abundant chlorinated C(2) groundwater pollutant on earth. However, a reductive in situ detoxification technology for this compound does not exist. Although anaerobic dehalorespiring bacteria are known to catalyze several dechlorination steps in the reductive-degradation pathway of chlorinated ethenes and ethanes, no appropriate isolates that selectively and metabolically convert them into completely dechlorinated end products in defined growth media have been reported. Here we report on the isolation of Desulfitobacterium dichloroeliminans strain DCA1, a nutritionally defined anaerobic dehalorespiring bacterium that selectively converts 1,2-dichloroethane and all possible vicinal dichloropropanes and -butanes into completely dechlorinated end products. Menaquinone was identified as an essential cofactor for growth of strain DCA1 in pure culture. Strain DCA1 converts chiral chlorosubstrates, revealing the presence of a stereoselective dehalogenase that exclusively catalyzes an energy-conserving anti mechanistic dichloroelimination. Unlike any known dehalorespiring isolate, strain DCA1 does not carry out reductive hydrogenolysis reactions but rather exclusively dichloroeliminates its substrates. This unique dehalorespiratory biochemistry has shown promising application possibilities for bioremediation purposes and fine-chemical synthesis.
De Wildeman
Stefaan
S
Laboratory for Microbial Ecology and Technology, Ghent University, B-9000 Ghent, Belgium.
Diekert
Gabriele
G
Van Langenhove
Herman
H
Verstraete
Willy
W
D000473:Alkanes / Q000737:chemistry / Q000378:metabolism*; D000693:Anaerobiosis; D004275:DNA, Ribosomal / Q000235:genetics / Q000302:isolation & purification; D045858:Desulfitobacterium / Q000145:classification / Q000302:isolation & purification / Q000378:metabolism*; D004579:Electron Transport; D005025:Ethylene Dichlorides / Q000378:metabolism*; D006867:Hydrolases / Q000378:metabolism; D007700:Kinetics; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013379:Substrate Specificity
D000473:Alkanes; D004275:DNA, Ribosomal; D005025:Ethylene Dichlorides; D012336:RNA, Ribosomal, 16S; C024565:ethylene dichloride; D006867:Hydrolases