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Cretnik, S. ; Thoreson, K.A. ; Bernstein, A. ; Ebert, K.* ; Buchner, D.* ; Laskov, C.* ; Haderlein, S.* ; Shouakar-Stash, O.* ; Kliegman, S.* ; McNeill, K.* ; Elsner, M.

Reductive dechlorination of TCE by chemical model systems in comparison to dehalogenating bacteria: Insights from dual element isotope analysis (13C/12C, 37Cl/35Cl).

Environ. Sci. Technol. 47, 6855-6863 (2013)
DOI PMC
Open Access Green as soon as Postprint is submitted to ZB.
Chloroethenes like trichloroethene (TCE) are prevalent environmental contaminants, which may be degraded through reductive dechlorination. Chemical models such as cobalamine (vitamin B12) and its simplified analogue cobaloxime have served to mimic microbial reductive dechlorination. To test whether in vitro and in vivo mechanisms agree, we combined carbon and chlorine isotope measurements of TCE. Degradation-associated enrichment factors εcarbon and εchlorine (i.e., molecular-average isotope effects) were -12.2‰ ± 0.5‰ and -3.6‰ ± 0.1‰ with Geobacter lovleyi strain SZ; -9.1‰ ± 0.6‰ and -2.7‰ ± 0.6‰ with Desulfitobacterium hafniense Y51; -16.1‰ ± 0.9‰ and -4.0‰ ± 0.2‰ with the enzymatic cofactor cobalamin; -21.3‰ ± 0.5‰ and -3.5‰ ± 0.1‰ with cobaloxime. Dual element isotope slopes m = Δδ(13)C/ Δδ(37)Cl ≈ εcarbon/εchlorine of TCE showed strong agreement between biotransformations (3.4 to 3.8) and cobalamin (3.9), but differed markedly for cobaloxime (6.1). These results (i) suggest a similar biodegradation mechanism despite different microbial strains, (ii) indicate that transformation with isolated cobalamin resembles in vivo transformation and (iii) suggest a different mechanism with cobaloxime. This model reactant should therefore be used with caution. Our results demonstrate the power of two-dimensional isotope analyses to characterize and distinguish between reaction mechanisms in whole cell experiments and in vitro model systems.
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Publication type Article: Journal article
Document type Scientific Article
Keywords Solution Reaction-kinetics ; Chlorinated Ethenes ; Vinyl-chloride ; Vitamin-b-12-catalyzed Dechlorination ; Dehalospirillum-multivorans ; Reaction-mechanisms ; Mediated Reduction ; Strain Y51 ; Fractionation ; Tetrachloroethene
ISSN (print) / ISBN 0013-936X
e-ISSN 1520-5851
Journal Environmental Science & Technology
Quellenangaben Volume: 47, Issue: 13, Pages: 6855-6863 Article Number: , Supplement: ,
Publisher American Chemical Society (ACS)
Publishing Place Washington, DC
Reviewing status Peer reviewed
Institute(s) Institute of Groundwater Ecology (IGOE)