Poster Presentation Australian Microbial Ecology 2019

Community structure and dynamics of petroleum-degrading microbes in subsurface environments of the North West Shelf, WA  (#112)

Darren Cheah 1 , Cornelia Wuchter 1 , Alan G. Scarlett 1 , Kliti Grice 1 , Marco Coolen 1
  1. Western Australian Organic & Isotope Geochemistry Centre (WA-OIGC), Bentley, WA, Australia

Subsurface petroleum environments, which include crude oil, natural gas, and unconventional oil and gas deposits, are indigenous habitats for anaerobic microbial communities that degrade petroleum compounds for their metabolic activities1. Petroleum reserves in the North West Shelf (NWS) of Western Australia are important energy resources for the Australian economy2, but biodegraded crude oils complicate extraction and purification processes3. There have been extensive geochemical studies carried out on petroleum biodegradation in the NWS4,5, but there is a lack of microbial ecology data pertaining to biodegraded petroleum in corresponding reservoirs. Reservoir temperature is the primary control on microbial growth and biodegradation rates, but salinity, fresh oil recharge rates, nutrient composition and availability, fluid migration, and build-up of intermediates also interactively influence microbial activity6. The microbial communities in subsurface petroleum environments work within syntrophic consortia that degrade petroleum compounds across varying metabolic and redox conditions7, through which methane is discharged as a terminal product8,9. This study aims to characterise community structure and dynamics of petroleum-degrading microbes in the subsurface, which could be further applied to secondary crude oil extraction, as well as methane production from terminal crude oil degradation. Microbial diversity and function in relation to petroleum biodegradation are analysed by metagenomic and metatranscriptomic methods, while organic geochemical methods and compound-specific isotope analysis (CSIA) are used to characterise metabolite abundances and biodegradation pathways. Trace metal and inorganic components are also analysed to characterise influences of nutrients and other volatiles. Finally, anaerobic incubation experiments are being conducted under various substrate and media inoculations to further characterise microbial community dynamics under controlled conditions, as well as their viability for microbially enhanced oil recovery and methane production.

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