UC San Diego

Deepwater Horizon oil spill was the world’s largest marine oil spills in history. This spill was unique in that a large proportion of the hydrocarbon was released into the deep ocean. Microbial communities present in the Gulf of Mexico rapidly responded to the oil spill. In order to understand the process of hydrocarbon degradation by deep-sea microbes, it is important to determine when and under which conditions they are metabolically active. Here we report on the impacts of high pressure on the microbial growth and protein synthesis activity of hydrocarbon-degrading microbes isolated from the Gulf of Mexico, which included Halomonas titanicae, Shewanella indicae and Alcanivorax xenomutans. Bioorthogonal noncanonical amino acid tagging (BONCAT) is a method that uses a methionine analog to fluorescently tag cells undergoing active protein synthesis. We use BONCAT to follow the activity of microbes under atmospheric and high pressure. Actively growing cells that take up these methionine analogs are subsequently fluorescently tagged using click chemistry, and assessed by flow cytometry. The results showed that all three stains grown best in hexadecane with corexit. High hydrostatic pressure (10 and 25 MPa) inhibited the aerobic growth of A. xenomutans, while didn’t show clear impacts on the growth of H. titanicae and S. indica. BONCAT results demonstrated that high hydrostatic pressures had negative impacts on the metabolic activity of A. xenomutans and H. titanicae, while did not show significant effects on the protein synthesis of S. indica. In general, the effects of high pressure on the microbial activity are species specific.