Reductive Dechlorination of TCE by Chemical Model Systems in Comparison to Dehalogenating Bacteria: Insights from Dual Element Isotope Analysis (13C/12C, 37Cl/35<

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• 作者：Stefan Cretnik ; Kristen A. Thoreson ; Anat Bernstein ; Karin Ebert ; Daniel Buchner ; Christine Laskov ; Stefan Haderlein ; Orfan Shouakar-Stash ; Sarah Kliegman ; Kristopher McNeill ; Martin Elsner
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2013
• 出版时间：July 2, 2013
• 年：2013
• 卷：47
• 期：13
• 页码：6855-6863
• 全文大小：365K
• 年卷期：v.47,no.13(July 2, 2013)
• ISSN：1520-5851

文摘

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 蔚_carbon and 蔚_chlorine (i.e., molecular-average isotope effects) were 鈭?2.2鈥?卤 0.5鈥?and 鈭?.6鈥?卤 0.1鈥?with Geobacter lovleyi strain SZ; 鈭?.1鈥?卤 0.6鈥?and 鈭?.7鈥?卤 0.6鈥?with Desulfitobacterium hafniense Y51; 鈭?6.1鈥?卤 0.9鈥?and 鈭?.0鈥?卤 0.2鈥?with the enzymatic cofactor cobalamin; 鈭?1.3鈥?卤 0.5鈥?and 鈭?.5鈥?卤 0.1鈥?with cobaloxime. Dual element isotope slopes m = 螖未¹³C/ 螖未³⁷Cl 鈮?蔚_carbon/蔚_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.