Microbial Ecology of Subsurface Oil Sands Deposits in Northern Alberta, Canada [article]

Christina M. Ridley, University Of Calgary, University Of Calgary, Lisa Marie Gieg, Gerrit Voordouw
The subsurface Athabasca Oil Sands in northern Alberta, Canada, is an important yet understudied microbial habitat. Over geological time, progressive biodegradation of low molecular weight hydrocarbons by indigenous microorganisms has resulted in an enrichment of high molecular weight hydrocarbons known as bitumen. This is an extreme environment characterized by low water and nutrient availability, thereby resulting in low microbial biomass. The objective of this study was to characterize the
more » ... crobial ecology of this unique ecosystem, which could ultimately provide a basis for the development of microbially enhanced oil recovery (MEOR) technologies. To that end, pristine core samples were collected from 220 to 320 meters below the surface during 3 annual field trips. Due to the high bitumen and low biomass content of the core samples, extensive method development and validation was performed to identify a robust molecular biological workflow that would allow for consistently successful extraction, amplification and sequencing of genomic DNA from core samples. This molecular biological method was then used to characterize the prokaryotic and eukaryotic microbial communities of the subsurface oil sands through 16S and 18S rRNA gene sequencing. Results revealed a surprising predominance of aerobic and facultative microorganisms in an environment that is traditionally considered anoxic. The genera Pseudomonas, Acinetobacter and Fontibacter were the dominant prokaryotes in all core samples (average relative sequence abundance >5%). Methanoculleus was the only methanogen detected at an average relative sequence abundance >1%. Fungi from the family Trichocomaceae and the order Hypocreales were the prevailing Eukaryotes. Core sample incubations were used to determine the effects of atmosphere and temperature on microbial community succession. Microcosms were established under aerobic, microaerobic and anaerobic atmospheres at reservoir (8°C), mesophilic (33°C) and thermophilic (60°C) temperatures. Results indicate [...]
doi:10.11575/prism/32803 fatcat:4xnvsjnqvrcethelttv7j2uwzq