Journal
ENVIRONMENTAL SCIENCE & TECHNOLOGY
Volume 53, Issue 8, Pages 4245-4254Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.est.8b06643
Keywords
-
Categories
Funding
- German National Science Foundation (DFG) [DFG NI1323/2, EL 266/3-1, EL 266/3-2]
- German-Israeli Foundation for Scientific Research and Development (GIF) [I-1267-307.8/2014]
- US DOD [W912HQ-15-C-0014]
- Natural Sciences and Research Council of Canada
Ask authors/readers for more resources
Tetrachloroethene (PCE) and trichloroethene (TCE) are significant groundwater contaminants. Microbial reductive dehalogenation at contaminated sites can produce nontoxic ethene but often stops at toxic cis-1,2-dichloroethene (cis-DCE) or vinyl chloride (VC). The magnitude of carbon relative to chlorine isotope effects (as expressed by Lambda(C/Cl), the slope of delta C-13 versus delta Cl-37 regressions) was recently recognized to reveal different reduction mechanisms with vitamin B-12 as a model reactant for reductive dehalogenase activity. Large Lambda(C/Cl) values for cis-DCE reflected cob(I)alamin addition followed by protonation, whereas smaller Lambda(C/Cl) values for PCE evidenced cob(I)alamin addition followed by Cl- elimination. This study addressed dehalogenation in actual microorganisms and observed identical large Lambda(C/Cl) values for cis-DCE (Lambda(C/Cl) = 10.0 to 17.8) that contrasted with identical smaller Lambda(C/Cl) for TCE and PCE (Lambda(C/Cl) = 2.3 to 3.8). For TCE, the trend of small Lambda(C/Cl) could even be reversed when mixed cultures were precultivated on VC or DCEs and subsequently confronted with TCE (Lambda(C/Cl) = 9.0 to 18.2). This observation provides explicit evidence that substrate adaptation must have selected for reductive dehalogenases with different mechanistic motifs. The patterns of Lambda(C/Cl) are consistent with practically all studies published to date, while the difference in reaction mechanisms offers a potential answer to the long-standing question of why bioremediation frequently stalls at cis-DCE.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available