title: Characterization of toluene and ethylbenzene biodegradation under nitrate-, iron(III)- and manganese(IV)-reducing conditions by compound-specific isotope analysis.
abstract: Ethylbenzene and toluene degradation under nitrate-, Mn(IV)-, or Fe(III)-reducing conditions was investigated by compound specific stable isotope analysis (CSIA) using three model cultures (Aromatoleum aromaticum EbN1, Georgfuchsia toluolica G5G6, and a Azoarcus-dominated mixed culture). Systematically lower isotope enrichment factors for carbon and hydrogen were observed for particulate Mn(IV). The increasing diffusion distances of toluene or ethylbenzene to the solid Mn(IV) most likely caused limited bioavailability and hence resulted in the observed masking effect. The data suggests further ethylbenzene hydroxylation by ethylbenzene dehydrogenase (EBDH) and toluene activation by benzylsuccinate synthase (BSS) as initial activation steps. Notably, significantly different values in dual isotope analysis were detected for toluene degradation by G. toluolica under the three studied redox conditions, suggesting variations in the enzymatic transition state depending on the available TEA. The results indicate that two-dimensional CSIA has significant potential to assess anaerobic biodegradation of ethylbenzene and toluene at contaminated sites.
authors.affiliation: Department of Isotope Biogeochemistry, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany; Faculty of Biology, University of Freiburg, Freiburg, Germany.
authors.forename: Conrad
authors.initials: C
authors.lastname: Dorer
authors.affiliation: Department of Isotope Biogeochemistry, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany. Electronic address: carsten.vogt@ufz.de.
authors.forename: Carsten
authors.initials: C
authors.lastname: Vogt
authors.affiliation: Department of River Ecology, UFZ - Helmholtz Centre for Environmental Research, Magdeburg, Germany.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Neu
authors.affiliation: Department of Isotope Biogeochemistry, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany.
authors.forename: Hryhoriy
authors.initials: H
authors.lastname: Stryhanyuk
authors.affiliation: Department of Isotope Biogeochemistry, UFZ - Helmholtz Centre for Environmental Research, Leipzig, Germany.
authors.forename: Hans-Hermann
authors.initials: HH
authors.lastname: Richnow
mesh_terms: D001555:Benzene Derivatives / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002244:Carbon; D019755:Carbon-Carbon Lyases; D005290:Ferric Compounds / Q000378:metabolism; D006859:Hydrogen; D007501:Iron / Q000737:chemistry; D007554:Isotopes / Q000032:analysis; D008345:Manganese / Q000737:chemistry; D008956:Models, Chemical; D009566:Nitrates / Q000737:chemistry / Q000378:metabolism; D009589:Nitrogen Oxides; D010084:Oxidation-Reduction; D014050:Toluene / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001555:Benzene Derivatives; D005290:Ferric Compounds; D007554:Isotopes; D009566:Nitrates; D009589:Nitrogen Oxides; D014050:Toluene; D008345:Manganese; D002244:Carbon; D006859:Hydrogen; D007501:Iron; D019755:Carbon-Carbon Lyases; C114354:benzylsuccinate synthase; C004912:ethylbenzene
keywords: Dual isotope analysis; Isotope fractionation; Manganese reduction