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Title: Dual Carbon–Chlorine Isotope Analysis Indicates Distinct Anaerobic Dichloromethane Degradation Pathways in Two Members of Peptococcaceae

Abstract

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 (H 2), 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 (ε C and ε Cl) of -42.4 ± 0.7‰ and -5.3 ± 0.1‰, respectively, were measured in D. formicoaceticum cultures. A similar ε Cl of -5.2 ± 0.1‰, but a substantially lower ε C of -18.3 ± 0.2‰, were determined for Ca. Dichloromethanomonas elyunquensis. The ε C and εCl values resulted in distinctly different dual element C–Cl isotope correlations (Λ C/Cl = Δδ 13C/Δδ 37Cl) of 7.89 ± 0.12 and 3.40 ± 0.03 for D. formicoaceticum and Ca. Dichloromethanomonas elyunquensis, respectively. The distinct Λ C/Cl values obtained for the two cultures imply mechanistically distinct C–Cl bond cleavagemore » 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.« less

Authors:
 [1];  [2];  [3];  [4];  [3];  [3];  [5];  [6]; ORCiD logo [7]
  1. Univ. of Tennessee, Knoxville, TN (United States). Center for Environmental Biotechnology, Dept. of Civil and Environmental Engineering, and Dept. of Microbiology
  2. 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,
  3. Univ. of Toronto, Toronto, Ontario (Canada). Dept. of Earth Sciences
  4. Georgia Inst. of Technology, Atlanta, GA (United States). School of Biology
  5. DuPont de Nemours and Company, Wilmington, DE (United States). DuPont Corporate Remediation Group
  6. The Chemours Company, Wilmington, DE (United States)
  7. 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
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1474553
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Environmental Science and Technology
Additional Journal Information:
Journal Volume: 52; Journal Issue: 15; Journal ID: ISSN 0013-936X
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Chen, Gao, Shouakar-Stash, Orfan, Phillips, Elizabeth, Justicia-Leon, Shandra D., Gilevska, Tetyana, Sherwood Lollar, Barbara, Mack, E. Erin, Seger, Edward S., and Löffler, Frank E. Dual Carbon–Chlorine Isotope Analysis Indicates Distinct Anaerobic Dichloromethane Degradation Pathways in Two Members of Peptococcaceae. United States: N. p., 2018. Web. doi:10.1021/acs.est.8b01583.
Chen, Gao, Shouakar-Stash, Orfan, Phillips, Elizabeth, Justicia-Leon, Shandra D., Gilevska, Tetyana, Sherwood Lollar, Barbara, Mack, E. Erin, Seger, Edward S., & Löffler, Frank E. Dual Carbon–Chlorine Isotope Analysis Indicates Distinct Anaerobic Dichloromethane Degradation Pathways in Two Members of Peptococcaceae. United States. doi:10.1021/acs.est.8b01583.
Chen, Gao, Shouakar-Stash, Orfan, Phillips, Elizabeth, Justicia-Leon, Shandra D., Gilevska, Tetyana, Sherwood Lollar, Barbara, Mack, E. Erin, Seger, Edward S., and Löffler, Frank E. Thu . "Dual Carbon–Chlorine Isotope Analysis Indicates Distinct Anaerobic Dichloromethane Degradation Pathways in Two Members of Peptococcaceae". United States. doi:10.1021/acs.est.8b01583. https://www.osti.gov/servlets/purl/1474553.
@article{osti_1474553,
title = {Dual Carbon–Chlorine Isotope Analysis Indicates Distinct Anaerobic Dichloromethane Degradation Pathways in Two Members of Peptococcaceae},
author = {Chen, Gao and Shouakar-Stash, Orfan and Phillips, Elizabeth and Justicia-Leon, Shandra D. and Gilevska, Tetyana and Sherwood Lollar, Barbara and Mack, E. Erin and Seger, Edward S. and Löffler, Frank E.},
abstractNote = {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.},
doi = {10.1021/acs.est.8b01583},
journal = {Environmental Science and Technology},
number = 15,
volume = 52,
place = {United States},
year = {2018},
month = {7}
}

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