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Reinnicke, S. ; Simonsen, A.* ; Sørensen, S.R.* ; Aamand, J.* ; Elsner, M.

C and N isotope fractionation during biodegradation of the pesticide metabolite 2,6-dichlorobenzamide (BAM): Potential for environmental assessments.

Environ. Sci. Technol. 46, 1447-1454 (2012)
DOI PMC
Open Access Green as soon as Postprint is submitted to ZB.
2,6-Dichlorobenzamide (BAM) is a metabolite of the herbicide 2,6-dichlorobenzonitrile (dichlobenil), and a prominent groundwater contaminant. Observable compound-specific isotope fractionation during BAM formation-through transformation of dichlobenil by Rhodococcus erythropolis DSM 9685-was small. In contrast, isotope fractionation during BAM degradation-with Aminobacter sp. MSH1 and ASI1, the only known bacterial strains capable of mineralizing BAM-was large, with pronounced carbon (ε(C) = -7.5‰ to -7.8‰) and nitrogen (ε(N) = -10.7‰ to -13.5‰) isotopic enrichment factors. BAM isotope values in natural samples are therefore expected to be dominated by the effects of its degradation rather than formation. Dual isotope slopes Δ (=Δδ(15)N/Δδ(13)C ≈ ε(N)/ε(C)) showed only small differences for MSH1 (1.75 ± 0.03) and ASI1 (1.45 ± 0.03) suggesting similar transformation mechanisms of BAM hydrolysis. Observations are in agreement with either a tetrahedral intermediate promoted by OH(-) or H(3)O(+) catalysis, or a concerted reaction mechanism. Therefore, owing to consistent carbon isotopic fractionation, isotope shifts of BAM can be linked to BAM biodegradation, and may even be used to quantify degradation of this persistent metabolite. In contrast, nitrogen isotope values may be rather indicative of different sources. Our results delineate a new approach to assessing the fate of BAM in the environment.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
Keywords benzene biodegradation; herbicide dichlobenil; microbial dechlorination; organic contaminants; degradation pathways; carbon; soils; transformation; mineralization; hydrolysis
ISSN (print) / ISBN 0013-936X
e-ISSN 1520-5851
Journal Environmental Science & Technology
Quellenangaben Volume: 46, Issue: 3, Pages: 1447-1454 Article Number: , Supplement: ,
Publisher ACS
Publishing Place Washington, DC
Non-patent literature Publications
Reviewing status Peer reviewed
Institute(s) Institute of Groundwater Ecology (IGOE)