A research team at Lawrence Berkeley National Laboratory has replicated the water conditions in the areas affected by the Deepwater Horizon oil spill and isolated the oil-eating strains of bacteria that helped to clean up the spill plume below the surface.
The Macondo well spilled four million barrels of crude into the Gulf, the largest unintentional spill in history. But almost half of the total amount remained below the surface, making it difficult to study. The team, led by microbial ecologist Gary Andersen, collected deep ocean water from the region and added oil and dispersants to see what the local microbes would do. They discovered a new, fast-growing, oil-eating bacterium that they have dubbed bermanella macondoprimitus, along with a community of other deep-dwelling species that have streamlined genes for degrading oil.
Andersen says that the oft-maligned dispersants used in the cleanup actually boosted these microbes' performance. "Our study demonstrated the importance of using dispersants in producing neutrally buoyant, tiny oil droplets, which kept much of the oil from reaching the ocean surface,” Andersen said. “Naturally occurring microbes at this depth are highly specialized in growing by using specific components of the oil for their food source. So the oil droplets provided a large surface area for the microbes to chew up the oil.”
However, this does not mean that Andersen's team has found a silver bullet for spill cleanup. These bacteria evolved for the Gulf environment and can't be transplanted to other waters. In addition, not all petroleum disperses in the water column: heavier fractions like bitumen sink to the bottom and settle. Many of these long-chain hydrocarbons are also harder to digest, making them more resistant to microbial degradation.