Small 13C/12C Fractionation Contrasts with Large Enantiomer Fractionation in Aerobic Biodegradation of Phenoxy Acids
| Autor: | Philip Weyrauch, Eva C. Magana Lopez, Martin Elsner, Sebastian R. Sørensen, Erkin Gözdereliler, Hans-Peter E. Kohler, Shiran Qiu, Rainer U. Meckenstock |
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| Rok vydání: | 2014 |
| Předmět: |
Carbon Isotopes
Chromatography Bacteria biology Herbicides Stereoisomerism General Chemistry Fractionation Chemical Fractionation Biodegradation Phenoxyacetates MCPA Aerobiosis Enzyme assay chemistry.chemical_compound Biodegradation Environmental Isotope fractionation chemistry Isotopes of carbon biology.protein Environmental Chemistry 2 4-Dichlorophenoxyacetic Acid Enantiomer Enzyme Assays Isotope analysis |
| Zdroj: | Environmental Science & Technology. 48:5501-5511 |
| ISSN: | 1520-5851 0013-936X |
| DOI: | 10.1021/es405103g |
| Popis: | 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. |
| Databáze: | OpenAIRE |
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