Microbial Communities in Bulk Fluids and Biofilms of a North Slope Oil Facility have Similar Composition but Different Structure

The oil-water gas environments of oil production facilities harbor abundant and diverse microbial communities that can participate in deleterious processes such as biocorrosion. Several molecular methods, including pyrosequencing of 16S rRNA libraries, were used to characterize the microbial communities from an oil production facility on the Alaskan North Slope. The communities in produced water and a sample from the "envelope" of a pipeline inspection gauge (PIG) were compared in order to identify specific populations or community structures associated with biocorrosion. The PIGs are used for physical mitigation of pipeline corrosion and fouling and the samples are enriched in surface-associated solids (i.e., parrafins, minerals, and biofilm) and coincidentally, microorganisms (1.2x10^5-fold). Throughout the oil production facility, bacteria were more abundant (10 to 150-fold) than archaea, with thermophilic members of the phyla Firmicutes (thermoanaerobacter and Thermacetogenium) and Synergistes (Thermovirga) dominating the community. However, the structure of the PIG community was distinct due to the increased relative abundances of the genera Thermacetogenium and Thermovirga. The data presented here suggests that bulk fluid is representative of the composition of biofilm communities associated with biocorrosion but that certain populations are more abundant in biofilms, which should be the focus of monitoring and mitigation strategies.