Functional gene diversity and expression in methane-hydrate bearing deep subsurface sediments

Methane is a critical component of the deep subsurface. In shallow marine sediments, anaerobic oxidation of methane (AOM) is coupled to sulfate reduction. However, relatively little is known about which microbial metabolisms are active in deeply buried sediment containing methane hydrates, particularly with regard to alternative electron acceptors that could fuel deep AOM. We propose to determine which microbial population(s) and functional genes are active in the deep biosphere beneath Hydrate Ridge offshore Oregon by sequencing metagenomes and 16S amplicons from samples drilled on ODP Leg 204 and archived for future molecular analysis. We will analyze gene diversity and expression in six geochemically distinct zones from 2 to 139 meters below the seafloor with the goal of evaluating the relationship between geochemical conditions (i.e. sulfate, iron and manganese availability) and microbial metabolic activity.