Dual Carbon–Chlorine Isotope Analysis Indicates Distinct Anaerobic Dichloromethane Degradation Pathways in Two Members of Peptococcaceae
Journal Article
·
· Environmental Science and Technology
- Univ. of Tennessee, Knoxville, TN (United States). Center for Environmental Biotechnology, Dept. of Civil and Environmental Engineering, and Dept. of Microbiology
- Isotope Tracer Technologies Inc. (IT2), Waterloo, Ontario (Canada); Univ. of Waterloo, Waterloo, Ontario (Canada). Dept. of Earth and Environmental Sciences; Univ. of Guelph, Guelph, Ontario (Canada). School of Engineering,
- Univ. of Toronto, Toronto, Ontario (Canada). Dept. of Earth Sciences
- Georgia Inst. of Technology, Atlanta, GA (United States). School of Biology
- DuPont de Nemours and Company, Wilmington, DE (United States). DuPont Corporate Remediation Group
- The Chemours Company, Wilmington, DE (United States)
- Univ. of Tennessee, Knoxville, TN (United States). Center for Environmental Biotechnology, Dept. of Civil and Environmental Engineering, and Dept. of Microbiology; Univ. of TN and Oak Ridge National Lab., Oak Ridge, TN (United States). Oak Ridge National Laboratory (UT-ORNL) Joint Institute for Biological Sciences (JIBS) and Biosciences Division; University of Tennessee, Knoxville, TN (United States). Dept. of Biosystems Engineering and Soil Science
Dichloromethane (DCM) is a probable human carcinogen and frequent groundwater contaminant and contributes to stratospheric ozone layer depletion. DCM is degraded by aerobes harboring glutathione-dependent DCM dehalogenases; however, DCM contamination occurs in oxygen-deprived environments, and much less is known about anaerobic DCM metabolism. Some members of the Peptococcaceae family convert DCM to environmentally benign products including acetate, formate, hydrogen (H2), and inorganic chloride under strictly anoxic conditions. The current study applied stable carbon and chlorine isotope fractionation measurements to the axenic culture Dehalobacterium formicoaceticum and to the consortium RM comprising DCM degrader Candidatus Dichloromethanomonas elyunquensis. Degradation-associated carbon and chlorine isotope enrichment factors (εC and εCl) of -42.4 ± 0.7‰ and -5.3 ± 0.1‰, respectively, were measured in D. formicoaceticum cultures. A similar εCl of -5.2 ± 0.1‰, but a substantially lower εC of -18.3 ± 0.2‰, were determined for Ca. Dichloromethanomonas elyunquensis. The εC and εCl values resulted in distinctly different dual element C–Cl isotope correlations (ΛC/Cl = Δδ13C/Δδ37Cl) of 7.89 ± 0.12 and 3.40 ± 0.03 for D. formicoaceticum and Ca. Dichloromethanomonas elyunquensis, respectively. The distinct ΛC/Cl values obtained for the two cultures imply mechanistically distinct C–Cl bond cleavage reactions, suggesting that members of Peptococcaceae employ different pathways to metabolize DCM. These findings emphasize the utility of dual carbon–chlorine isotope analysis to pinpoint DCM degradation mechanisms and to provide an additional line of evidence that detoxification is occurring at DCM-contaminated sites.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC05-00OR22725
- OSTI ID:
- 1474553
- Journal Information:
- Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 15 Vol. 52; ISSN 0013-936X
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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