Oral Session I 022616 TR_HW

The Deepwater Horizon (DWH) blowout in the northern Gulf of Mexico represents one of the largest marine oil spills. Significant shifts in bacterial community composition in the water column correlated to the microbial degradation and utilization of oil hydrocarbons. Nevertheless, the full genetic potential and taxon-specific metabolisms of bacterial hydrocarbon degraders enriched during the DWH spill remain largely unresolved. To address this gap, we reconstructed genomes of novel, marine bacteria enriched from sea surface and plume spill communities by coupling stable-isotope probing with genomic reconstruction. Thereby, we could identify bacterial community members that actively assimilate alkane and polycyclic aromatic hydrocarbons (PAHs) and resolve their physiological capabilities. We reconstructed a total of 7 genomes, including one genome from an alkane SIP-enrichment using n-hexadecane and three genomes each from PAH SIP-enrichments using naphthalene or phenanthrene. Marinobacter represented the active, alkane-degrading SIPpopulation, while uncultured Alphaand Gammaproteobacteria, such as Thalassospira and Alcanivorax, characterized the PAH-degrading communities. Despite the observation that only Marinobacter actively degraded alkanes, metabolic pathways for alkane degradation were present in all of the 7 assembled high-quality genomes. Interestingly, the biochemical repertoire of PAH utilization varied among the different bacterial species and the combined capabilities of the microbial community exceeded those of its individual components. Altogether, this implies that the degradation of a complex hydrocarbon mixture requires the non-redundant capabilities of a complex oil-degrading community.