title: Anaerobic biodegradation of longer-chain n-alkanes coupled to methane production in oil sands tailings.
abstract: Extraction of bitumen from mined oil sands ores produces enormous volumes of tailings that are stored in settling basins (current inventory ≥ 840 million m(3)). Our previous studies revealed that certain hydrocarbons (short-chain n-alkanes [C(6)-C(10)] and monoaromatics [toluene, o-xylene, m-xylene]) in residual naphtha entrained in the tailings are biodegraded to CH(4) by a consortium of microorganisms. Here we show that higher molecular weight n-alkanes (C(14), C(16), and C(18)) are also degraded under methanogenic conditions in oil sands tailings, albeit after a lengthy lag (~180 d) before the onset of methanogenesis. Gas chromatographic analyses showed that the longer-chain n-alkanes each added at ~400 mg L(-1) were completely degraded by the resident microorganisms within ~440 d at ~20 °C. 16S rRNA gene sequence analysis of clone libraries implied that the predominant pathway of longer-chain n-alkane metabolism in tailings is through syntrophic oxidation of n-alkanes coupled with CO(2) reduction to CH(4). These studies demonstrating methanogenic biodegradation of longer-chain n-alkanes by microbes native to oil sands tailings may be important for effective management of tailings and greenhouse gas emissions from tailings ponds.
authors.affiliation: Department of Renewable Resources, University of Alberta, Edmonton, Alberta T6G 2E3, Canada. tariq.siddique@ualberta.ca
authors.forename: Tariq
authors.initials: T
authors.lastname: Siddique
authors.forename: Tara
authors.initials: T
authors.lastname: Penner
authors.forename: Kathleen
authors.initials: K
authors.lastname: Semple
authors.forename: Julia M
authors.initials: JM
authors.lastname: Foght
mesh_terms: D000473:Alkanes / Q000378:metabolism*; D000693:Anaerobiosis; D001105:Archaea / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001673:Biodegradation, Environmental; D002245:Carbon Dioxide / Q000378:metabolism; D002849:Chromatography, Gas; D019295:Computational Biology; D020564:Deltaproteobacteria / Q000235:genetics* / Q000378:metabolism; D006838:Hydrocarbons; D008697:Methane / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010578:Petroleum / Q000378:metabolism*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D014866:Waste Products / Q000032:analysis*
chemical_list: D000473:Alkanes; D006838:Hydrocarbons; D010578:Petroleum; D012336:RNA, Ribosomal, 16S; D014866:Waste Products; D002245:Carbon Dioxide; C006647:asphalt; D008697:Methane