title: DNA stable-isotope probing of oil sands tailings pond enrichment cultures reveals different key players for toluene degradation under methanogenic and sulfidogenic conditions.
abstract: Oil sands tailings ponds are anaerobic repositories of fluid wastes produced by extraction of bitumen from oil sands ores. Diverse indigenous microbiota biodegrade hydrocarbons (including toluene) in situ, producing methane, carbon dioxide and/or hydrogen sulfide, depending on electron acceptor availability. Stable-isotope probing of cultures enriched from tailings associated specific taxa and functional genes to (13)C6- and (12)C7-toluene degradation under methanogenic and sulfate-reducing conditions. Total DNA was subjected to isopycnic ultracentrifugation followed by gradient fraction analysis using terminal restriction fragment length polymorphism (T-RFLP) and construction of 16S rRNA, benzylsuccinate synthase (bssA) and dissimilatory sulfite reductase (dsrB) gene clone libraries. T-RFLP analysis plus sequencing and in silico digestion of cloned taxonomic and functional genes revealed that Clostridiales, particularly Desulfosporosinus (136 bp T-RF) contained bssA genes and were key toluene degraders during methanogenesis dominated by Methanosaeta. Deltaproteobacterial Desulfobulbaceae (157 bp T-RF) became dominant under sulfidogenic conditions, likely because the Desulfosporosinus T-RF 136 apparently lacks dsrB and therefore, unlike its close relatives, is presumed incapable of dissimilatory sulfate reduction. We infer incomplete oxidation of toluene by Desulfosporosinus in syntrophic association with Methanosaeta under methanogenic conditions, and complete toluene oxidation by Desulfobulbaceae during sulfate reduction.
authors: CW-405 Biological Sciences Centre, Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9 Canada.
authors: Nidal Abu
authors: NA
authors: Laban
authors: CW-405 Biological Sciences Centre, Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9 Canada.
authors: Anh
authors: A
authors: Dao
authors: CW-405 Biological Sciences Centre, Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9 Canada julia.foght@ualberta.ca.
authors: Julia
authors: J
authors: Foght
mesh_terms: D000123:Acetyltransferases / Q000235:genetics; D000693:Anaerobiosis / Q000502:physiology; D001483:Base Sequence; D001673:Biodegradation, Environmental; D019755:Carbon-Carbon Lyases / Q000235:genetics*; D003013:Clostridium / Q000235:genetics / Q000378:metabolism; D004247:DNA / Q000235:genetics; D015342:DNA Probes / Q000235:genetics; D020564:Deltaproteobacteria / Q000235:genetics* / Q000378:metabolism; D019605:Euryarchaeota / Q000235:genetics* / Q000378:metabolism; D050885:Hydrogensulfite Reductase / Q000235:genetics*; D007553:Isotope Labeling; D008697:Methane / Q000378:metabolism; D019640:Methanosarcinales / Q000235:genetics / Q000378:metabolism; D064307:Microbiota / Q000235:genetics / Q000502:physiology; D061329:Oil and Gas Fields; D010084:Oxidation-Reduction; D010459:Peptococcaceae / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length / Q000235:genetics; D061005:Ponds; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013431:Sulfates / Q000378:metabolism; D014050:Toluene / Q000378:metabolism
chemical_list: D015342:DNA Probes; D012336:RNA, Ribosomal, 16S; D013431:Sulfates; D014050:Toluene; D004247:DNA; D050885:Hydrogensulfite Reductase; D000123:Acetyltransferases; C022560:formate C-acetyltransferase; D019755:Carbon-Carbon Lyases; C114354:benzylsuccinate synthase; D008697:Methane
keywords: anaerobic toluene degradation; benzylsuccinate synthase; fumarate addition; methanogenesis; sulfate reduction; syntrophy; tailings