title: Roles of Thermophiles and Fungi in Bitumen Degradation in Mostly Cold Oil Sands Outcrops.
abstract: Oil sands are surface exposed in river valley outcrops in northeastern Alberta, where flat slabs (tablets) of weathered, bitumen-saturated sandstone can be retrieved from outcrop cliffs or from riverbeds. Although the average yearly surface temperature of this region is low (0.7°C), we found that the temperatures of the exposed surfaces of outcrop cliffs reached 55 to 60°C on sunny summer days, with daily maxima being 27 to 31°C. Analysis of the cooccurrence of taxa derived from pyrosequencing of 16S/18S rRNA genes indicated that an aerobic microbial network of fungi and hydrocarbon-, methane-, or acetate-oxidizing heterotrophic bacteria was present in all cliff tablets. Metagenomic analyses indicated an elevated presence of fungal cytochrome P450 monooxygenases in these samples. This network was distinct from the heterotrophic community found in riverbeds, which included fewer fungi. A subset of cliff tablets had a network of anaerobic and/or thermophilic taxa, including methanogens, Firmicutes, and Thermotogae, in the center. Long-term aerobic incubation of outcrop samples at 55°C gave a thermophilic microbial community. Analysis of residual bitumen with a Fourier transform ion cyclotron resonance mass spectrometer indicated that aerobic degradation proceeded at 55°C but not at 4°C. Little anaerobic degradation was observed. These results indicate that bitumen degradation on outcrop surfaces is a largely aerobic process with a minor anaerobic contribution and is catalyzed by a consortium of bacteria and fungi. Bitumen degradation is stimulated by periodic high temperatures on outcrop cliffs, which cause significant decreases in bitumen viscosity.
authors.affiliation: Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Man-Ling
authors.initials: ML
authors.lastname: Wong
authors.affiliation: Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Dongshan
authors.initials: D
authors.lastname: An
authors.affiliation: Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Sean M
authors.initials: SM
authors.lastname: Caffrey
authors.affiliation: Visual Genomics Centre, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Jung
authors.initials: J
authors.lastname: Soh
authors.affiliation: Department of Geoscience, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Dong
authors.affiliation: Graz Technical University, Institute of Molecular Biotechnology, AG Computational Biotechnology, Graz, Austria.
authors.forename: Christoph W
authors.initials: CW
authors.lastname: Sensen
authors.affiliation: Department of Geoscience, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Thomas B P
authors.initials: TB
authors.lastname: Oldenburg
authors.affiliation: Department of Geoscience, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Steve R
authors.initials: SR
authors.lastname: Larter
authors.affiliation: Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada voordouw@ucalgary.ca.
authors.forename: Gerrit
authors.initials: G
authors.lastname: Voordouw
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D001673:Biodegradation, Environmental; D003080:Cold Temperature; D005658:Fungi / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D006838:Hydrocarbons / Q000378:metabolism*; D059013:Microbial Consortia; D008969:Molecular Sequence Data; D061329:Oil and Gas Fields / Q000382:microbiology*; D010802:Phylogeny; D045483:Rivers / Q000737:chemistry / Q000382:microbiology; D013696:Temperature
chemical_list: D006838:Hydrocarbons; C006647:asphalt