title: Hydrogen Isotope Fractionation As a Tool to Identify Aerobic and Anaerobic PAH Biodegradation.
abstract: Aerobic and anaerobic polycyclic aromatic hydrocarbon (PAH) biodegradation was characterized by compound specific stable isotope analysis (CSIA) of the carbon and hydrogen isotope effects of the enzymatic reactions initiating specific degradation pathways, using naphthalene and 2-methylnaphtalene as model compounds. Aerobic activation of naphthalene and 2-methylnaphthalene by Pseudomonas putida NCIB 9816 and Pseudomonas fluorescens ATCC 17483 containing naphthalene dioxygenases was associated with moderate carbon isotope fractionation (εC = -0.8 ± 0.1‰ to -1.6 ± 0.2‰). In contrast, anaerobic activation of naphthalene by a carboxylation-like mechanism by strain NaphS6 was linked to negligible carbon isotope fractionation (εC = -0.2 ± 0.2‰ to -0.4 ± 0.3‰). Notably, anaerobic activation of naphthalene by strain NaphS6 exhibited a normal hydrogen isotope fractionation (εH = -11 ± 2‰ to -47 ± 4‰), whereas an inverse hydrogen isotope fractionation was observed for the aerobic strains (εH = +15 ± 2‰ to +71 ± 6‰). Additionally, isotope fractionation of NaphS6 was determined in an overlaying hydrophobic carrier phase, resulting in more reliable enrichment factors compared to immobilizing the PAHs on the bottle walls without carrier phase. The observed differences especially in hydrogen fractionation might be used to differentiate between aerobic and anaerobic naphthalene and 2-methylnaphthalene biodegradation pathways at PAH-contaminated field sites.
authors: UFZ-Helmholtz Centre for Environmental Research , Department of Isotope Biogeochemistry, Permoserstraße 15, 04318 Leipzig, Germany.|University of Freiburg , Faculty of Biology, Schaenzlestraße 1, 79104 Freiburg, Germany.
authors: Steffen
authors: S
authors: Kümmel
authors: UFZ-Helmholtz Centre for Environmental Research , Department of Isotope Biogeochemistry, Permoserstraße 15, 04318 Leipzig, Germany.
authors: Robert
authors: R
authors: Starke
authors: MPI-Max Planck Institute for Marine Microbiology , Department of Microbiology, Celsiusstrasse 1, 28359 Bremen, Germany.
authors: Gao
authors: G
authors: Chen
authors: UFZ-Helmholtz Centre for Environmental Research , Department of Isotope Biogeochemistry, Permoserstraße 15, 04318 Leipzig, Germany.|MPI-Max Planck Institute for Marine Microbiology , Department of Microbiology, Celsiusstrasse 1, 28359 Bremen, Germany.
authors: Florin
authors: F
authors: Musat
authors: UFZ-Helmholtz Centre for Environmental Research , Department of Isotope Biogeochemistry, Permoserstraße 15, 04318 Leipzig, Germany.
authors: Hans H
authors: HH
authors: Richnow
authors: UFZ-Helmholtz Centre for Environmental Research , Department of Isotope Biogeochemistry, Permoserstraße 15, 04318 Leipzig, Germany.
authors: Carsten
authors: C
authors: Vogt
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D002247:Carbon Isotopes / Q000032:analysis; D005591:Chemical Fractionation / Q000379:methods; D003903:Deuterium / Q000032:analysis; D004785:Environmental Pollutants / Q000737:chemistry / Q000378:metabolism*; D006859:Hydrogen / Q000737:chemistry*; D053858:Metabolic Networks and Pathways; D009281:Naphthalenes / Q000378:metabolism; D009587:Nitrogen Isotopes / Q000032:analysis; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D004785:Environmental Pollutants; D009281:Naphthalenes; D009587:Nitrogen Isotopes; D011084:Polycyclic Aromatic Hydrocarbons; C031721:naphthalene; D006859:Hydrogen; D003903:Deuterium; C027384:2-methylnaphthalene