High permeation rates in liposome systems explain rapid glyphosate biodegradation associated with strong isotope fractionation.
Environ. Sci. Technol. 52, 7259-7268 (2018)
Bacterial uptake of charged organic pollutants such as the widely used herbicide glyphosate is typically attributed to active transporters, whereas passive membrane permeation as an uptake pathway is usually neglected. For 1-palmitoyl-2-oleoyl-snglycero-3-phosphocholine (POPC) liposomes, the pH-dependent apparent membrane permeation coefficients (P-app) of glyphosate, determined by nuclear magnetic resonance (NMR) spectroscopy, varied from P-app (pH 7.0) = 3.7 (+/- 0.3) x 10(-7) m.s(-1) to P-app (pH 4.1) = 4.2 (+/- 0.1) x 10(-6) m.s(-1). The magnitude of this surprisingly rapid membrane permeation depended on glyphosate speciation and was, at circumneutral pH, in the range of polar, noncharged molecules. These findings point to passive membrane permeation as a potential uptake pathway during glyphosate biodegradation. To test this hypothesis, a Gram-negative glyphosate degrader, Ochrobactrum sp. FrEM, was isolated from glyphosate-treated soil and glyphosate permeation rates inferred from the liposome model system were compared to bacterial degradation rates. Estimated maximum permeation rates were, indeed, 2 orders of magnitude higher than degradation rates of glyphosate. In addition, biodegradation of millimolar glyphosate concentrations gave rise to pronounced carbon isotope fractionation with an apparent kinetic isotope effect, AKIE(carbon), of 1.014 +/- 0.003. This value lies in the range typical of non-masked enzymatic isotope fractionation demonstrating that glyphosate biodegradation was not subject to mass transfer limitations and glyphosate exchange across the cell membrane was rapid relative to enzymatic turnover.
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Publikationstyp
Artikel: Journalartikel
Dokumenttyp
Wissenschaftlicher Artikel
Typ der Hochschulschrift
Herausgeber
Schlagwörter
Bioavailability Restrictions; Aerobic Biodegradation; Unilamellar Vesicles; Bacterial-membranes; Mass-spectrometry; Resistant Crops; Arthrobacter Sp; Transport; Herbicide; Soil
Keywords plus
Sprache
Veröffentlichungsjahr
2018
Prepublished im Jahr
HGF-Berichtsjahr
2018
ISSN (print) / ISBN
0013-936X
e-ISSN
1520-5851
ISBN
Bandtitel
Konferenztitel
Konferzenzdatum
Konferenzort
Konferenzband
Quellenangaben
Band: 52,
Heft: 13,
Seiten: 7259-7268
Artikelnummer: ,
Supplement: ,
Reihe
Verlag
ACS
Verlagsort
Washington, DC
Tag d. mündl. Prüfung
0000-00-00
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Gutachter
Prüfer
Topic
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Veröffentlichungsdatum
0000-00-00
Anmeldedatum
0000-00-00
Anmelder/Inhaber
weitere Inhaber
Anmeldeland
Priorität
Begutachtungsstatus
Peer reviewed
POF Topic(s)
20403 - Sustainable Water Management
Forschungsfeld(er)
Environmental Sciences
PSP-Element(e)
G-504390-001
Förderungen
Copyright
Erfassungsdatum
2018-07-24