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Lihl, C. ; Douglas, L.M.* ; Franke, S.* ; Pérez-de-Mora, A. ; Meyer, A.H. ; Daubmeier, M. ; Edwards, E.A.* ; Nijenhuis, I.* ; Sherwood Lollar, B.* ; Elsner, M.

Mechanistic dichotomy in bacterial trichloroethene dechlorination revealed by carbon and chlorine isotope effects.

Environ. Sci. Technol. 53, 4245-4254 (2019)
Postprint DOI PMC
Open Access Green
Tetrachloroethene (PCE) and trichloroethene (TCE) are significant groundwater contaminants. Microbial reductive dehalogenation at contaminated sites can produce nontoxic ethene but often stops at toxic cis-1,2-dichloroethene (cis-DCE) or vinyl chloride (VC). The magnitude of carbon relative to chlorine isotope effects (as expressed by Lambda(C/Cl), the slope of delta C-13 versus delta Cl-37 regressions) was recently recognized to reveal different reduction mechanisms with vitamin B-12 as a model reactant for reductive dehalogenase activity. Large Lambda(C/Cl) values for cis-DCE reflected cob(I)alamin addition followed by protonation, whereas smaller Lambda(C/Cl) values for PCE evidenced cob(I)alamin addition followed by Cl- elimination. This study addressed dehalogenation in actual microorganisms and observed identical large Lambda(C/Cl) values for cis-DCE (Lambda(C/Cl) = 10.0 to 17.8) that contrasted with identical smaller Lambda(C/Cl) for TCE and PCE (Lambda(C/Cl) = 2.3 to 3.8). For TCE, the trend of small Lambda(C/Cl) could even be reversed when mixed cultures were precultivated on VC or DCEs and subsequently confronted with TCE (Lambda(C/Cl) = 9.0 to 18.2). This observation provides explicit evidence that substrate adaptation must have selected for reductive dehalogenases with different mechanistic motifs. The patterns of Lambda(C/Cl) are consistent with practically all studies published to date, while the difference in reaction mechanisms offers a potential answer to the long-standing question of why bioremediation frequently stalls at cis-DCE.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
Keywords Ratio Mass-spectrometry; Reductive Dechlorination; Dehalococcoides-ethenogenes; Vinyl-chloride; Microbial-degradation; Organic Contaminants; Fractionation; Tetrachloroethene; Ethene; Transformation
ISSN (print) / ISBN 0013-936X
e-ISSN 1520-5851
Journal Environmental Science & Technology
Quellenangaben Volume: 53, Issue: 8, Pages: 4245-4254 Article Number: , Supplement: ,
Publisher ACS
Publishing Place Washington, DC
Non-patent literature Publications
Reviewing status Peer reviewed
Institute(s) Institute of Groundwater Ecology (IGOE)