摘要：The Deepwater Horizon oil spill was one of the largest oil spills in history, and the fate of
this oil within the Gulf of Mexico ecosystem remains to be fully understood. The goal of
this study—conducted in mid-June of 2010, approximately two months after the oil spill
began—was to understand the key role that microbes would play in the degradation of the
oil in the offshore oligotrophic surface waters near the Deepwater Horizon site. As the
utilization of organic carbon by bacteria in the surface waters of the Gulf had been
previously shown to be phosphorus limited, we hypothesized that bacteria would be unable
to rapidly utilize the oil released from the Macondo well. Although phosphate was
scarce throughout the sampling region and microbes exhibited enzymatic signs
of phosphate stress within the oil slick, microbial respiration within the slick
was enhanced by approximately a factor of five. An incubation experiment to
determine hydrocarbon degradation rates confirmed that a large fraction of this
enhanced respiration was supported by hydrocarbon degradation. Extrapolating our
observations to the entire area of the slick suggests that microbes had the potential to
degrade a large fraction of the oil as it arrived at the surface from the well. These
observations decidedly refuted our hypothesis. However, a concomitant increase in
microbial abundance or biomass was not observed in the slick, suggesting that
microbial growth was nutrient limited; incubations amended with nutrients showed
rapid increases in cell number and biomass, which supported this conclusion.
Our study shows that the dynamic microbial community of the Gulf of Mexico
supported remarkable rates of oil respiration, despite a dearth of dissolved nutrients.
