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Qiu, S. ; Gözdereliler, E. ; Weyrauch, P. ; Lopez, E.C. ; Kohler, H.P.* ; Sørensen, S.R.* ; Meckenstock, R.U. ; Elsner, M.

Small 13C/12C fractionation contrasts with large enantiomer fractionation in aerobic biodegradation of phenoxy acids.

Environ. Sci. Technol. 48, 5501-5511 (2014)
DOI PMC
Open Access Green as soon as Postprint is submitted to ZB.
Phenoxy acid herbicides are important groundwater contaminants. Stable isotope analysis and enantiomer analysis are well-recognized approaches for assessing in situ biodegradation in the field. In an aerobic degradation survey with six phenoxyacetic acid and three phenoxypropionic acid-degrading bacteria we measured (a) enantiomer-specific carbon isotope fractionation of MCPP ((R,S)-2-(4-chloro-2-methylphenoxy)-propionic acid), DCPP ((R,S)-2-(2,4-dichlorophenoxy)-propionic acid), and 4-CPP ((R,S)-2-(4-chlorophenoxy)-propionic acid); (b) compound-specific isotope fractionation of MCPA (4-chloro-2-methylphenoxyacetic acid) and 2,4-D (2,4-dichlorophenoxyacetic acid); and (c) enantiomer fractionation of MCPP, DCPP, and 4-CPP. Insignificant or very slight (ε = -1.3‰ to -2.0‰) carbon isotope fractionation was observed. Equally small values in an RdpA enzyme assay (εea = -1.0 ± 0.1‰) and even smaller fractionation in whole cell experiments of the host organism Sphingobium herbicidovorans MH (εwc = -0.3 ± 0.1‰) suggest that (i) enzyme-associated isotope effects were already small, yet (ii) further masked by active transport through the cell membrane. In contrast, enantiomer fractionation in MCPP, DCPP, and 4-CPP was pronounced, with enantioselectivities (ES) of -0.65 to -0.98 with Sphingomonas sp. PM2, -0.63 to -0.89 with Sphingobium herbicidovorans MH, and 0.74 to 0.97 with Delftia acidovorans MC1. To detect aerobic biodegradation of phenoxypropionic acids in the field, enantiomer fractionation seems, therefore, a stronger indicator than carbon isotope fractionation.
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Publication type Article: Journal article
Document type Scientific Article
Keywords Sphingomonas-herbicidovorans Mh; Stable-isotope Fractionation; 2,4-dichlorophenoxyacetic Acid; Organic Contaminants; Natural Attenuation; Degrading Bacteria; Ground-water; Enantioselective Degradation; Limestone Aquifer; Chiral Herbicide
ISSN (print) / ISBN 0013-936X
e-ISSN 1520-5851
Journal Environmental Science & Technology
Quellenangaben Volume: 48, Issue: 10, Pages: 5501-5511 Article Number: , Supplement: ,
Publisher American Chemical Society (ACS)
Publishing Place Washington, DC
Reviewing status Peer reviewed
Institute(s) Institute of Groundwater Ecology (IGOE)