Oil spillsOil spill puzzle solved: Oil-eating bacteria consumed the Deepwater Horizon oil plume
The Deepwater Horizon oil spill in the Gulf of Mexico in 2010 is one of the most studied spills in history, yet scientists have not agreed on the role of microbes in eating up the oil. Now, a research team has identified all of the principal oil-degrading bacteria as well as their mechanisms for chewing up the many different components that make up the released crude oil.
The Deepwater Horizon oil spill in the Gulf of Mexico in 2010 is one of the most studied spills in history, yet scientists haven’t agreed on the role of microbes in eating up the oil. Now a research team at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) has identified all of the principal oil-degrading bacteria as well as their mechanisms for chewing up the many different components that make up the released crude oil.
The team, led by Berkeley Lab microbial ecologist Gary Andersen, is the first to simulate the conditions that occurred in the aftermath of the spill. Their study was published in the Proceedings of the National Academy of Sciences.
“This provides the most complete account yet of what was happening in the hydrocarbon plumes in the deep ocean during the event,” said Andersen. Berkeley Lab’s Ping Hu, the lead author of the study, added: “We simulated the conditions of the Gulf of Mexico oil spill in the lab and were able to understand the mechanisms for oil degradation from all of the principal oil-degrading bacteria that were observed in the original oil spill.”
LBL notes that this oil spill was the largest in history, with the release of 4.1 million barrels of crude oil as well as large amounts of natural gas from a mile below the surface of the ocean. After the initial explosion and uncontained release of oil, researchers observed a phenomenon that had not been seen before: More than 40 percent of the oil, combined with an introduced chemical dispersant, was retained in a plume nearly 100 miles long at this great depth.
Yet because of the difficulty in collecting samples from so far below the ocean surface, and because of the large area that was impacted by the spill, a number of gaps in understanding the fate of the oil over time remained.
Discovery of a new bacterium
Andersen and his team returned to the spill location four years later to collect water at depth. With the assistance of co-authors Piero Gardinali of Florida International University and Ron Atlas of the University of Louisville, a suspension of small, insoluble oil droplets was evenly distributed in bottles, along with the more soluble oil fractions and chemical dispersant to mimic the conditions of the oil plume. Over the next 64 days the composition of the microbes and the crude oil were intensively studied.
