S131: Metagenomic, metatranscriptomic, and single cell genomic analyses of the deep-sea microbial community response to the Deepwater Horizon oil spill

The Deepwater Horizon oil spill is the largest spill in US history. To assess the response of the deep-sea microbial communities in the Gulf of Mexico to this large-scale environmental perturbation two plume samples and one uncontaminated sample collected from plume depth were analyzed. Pyrotag sequence analysis revealed that microbial diversity was significantly lower in the plume, with the order Oceanospirillales comprising 80-90% of the plume community, compared to 3% of the uncontaminated sample community. Analysis of assembled metagenomic sequences revealed numerous COGs were significantly different between the contaminated and uncontaminated samples. For example, a methyl-accepting chemotaxis protein, shown to be involved in bacterial chemotactic response to hydrocarbons, was the most statistically significant in both plume samples relative to the control. Analysis of unassembled reads revealed that proteins involved in degradation of simple aromatics and alkanes were more abundant in the plume interval compared to the uncontaminated sample. Proteins involved in methane oxidation were lower in the proximal sample, increased in the distal plume, but remained lower than the uncontaminated sample. Analysis of assembled and unassembled metatranscriptomic data confirmed that proteins involved in hydrocarbon degradation that were identified as most abundant in the plume relative to the control were, in fact, expressed in situ. Further, methyl-accepting chemotaxis proteins were expressed in the plume interval. Genomic analysis of an Oceanospirillales single cell obtained from the proximal plume validated our metagenome and metatranscriptome derived findings in that the single cell genome encoded hydrocarbon degradation and chemotaxis.