Reductive dechlorination of TCE by chemical model systems in comparison to dehalogenating bacteria: insights from dual element isotope analysis (13C/12C, 37Cl/35Cl)
| Autor: | Kristen A. Thoreson, Martin Elsner, Christine Laskov, Daniel Buchner, Orfan Shouakar-Stash, Stefan Cretnik, Kristopher McNeill, Sarah Kliegman, Karin Ebert, Anat Bernstein, Stefan B. Haderlein |
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| Rok vydání: | 2013 |
| Předmět: |
Desulfitobacterium
Geobacter lovleyi Isotopes Kinetic isotope effect polycyclic compounds Reductive dechlorination Organometallic Compounds Environmental Chemistry Carbon Isotopes Isotope biology Chemistry Isotopes of chlorine Desulfitobacterium hafniense General Chemistry biology.organism_classification Trichloroethylene Vitamin B 12 Biodegradation Environmental Isotopes of carbon Environmental chemistry Chlorine Geobacter Oxidation-Reduction Water Pollutants Chemical |
| Zdroj: | Environmental sciencetechnology. 47(13) |
| ISSN: | 1520-5851 |
| Popis: | 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 e(carbon) and e(chlorine) (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 ≈ e(carbon)/e(chlorine) 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. |
| Databáze: | OpenAIRE |
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