Monday, July 25, 2011: 3:00 PM
Nottoway, 4th fl (Sheraton New Orleans)
To understand the response of microbes to oil and potential surfactant contamination we employed an in situ bacterial collection device consisting of Bio-Sep® (University of Tulsa) beads, a non-reactive matrix, baited with volatile crude oil from the MC252-wellhead. We explored microbial hydrocarbon degrading organisms by placing baited and control beads at four depths tethered to a drilling riser immediately adjacent to the site of the original spill and destructively sampled over four weeks. With increasing time at which the sample was taken we observed distinctive changes in microbial community composition and abundance between baited and control samples and by sample depth. We also surveyed microbial communities in filtered water samples in both the surface and deepwater plumes and outside the plume on several oceanographic cruises from May through August 2010. We used phylogenetic microarray analysis (PhyloChip) to characterize the composition, structure and activity of microbial communities in oil- and dispersant-affected waters. Results confirmed our earlier observations that the dispersed hydrocarbon plume stimulated deep-sea indigenous Gammaproteobacteria that are closely related to known oil degraders. We also observed that the microbial community composition within the hydrocarbon plume changed over time. Deepwater samples with reduced DO but no measureable hydrocarbons had a similar microbial composition to the plume samples including a reduced overall microbial diversity. We speculate that the microbial community persisted after biodegradation in these samples. Further analysis of the microarray data demonstrated that a subset of the 1.1 million PhyloChip probes reliably discriminate the in-the-plume microbes from the out-of-the-plume group.