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Bacteria rush in to gobble up oil plumes from Deepwater
By Casey Johnston
Researchers have discovered a large contingent of silent partners in the Deepwater oil spill cleanup—bacteria. Two samples of a deep-sea oil plume show that a high number of microbes have populated the oily area and are hacking away at the hydrocarbon concentration. The bacteria also seem to be using relatively little oxygen to metabolize parts of the oil, minimizing their own environmental impact.
The samples of water were taken inside and outside a large oil plume about 6 miles from the well site and three-quarters of a mile below the surface, and date from a month after the Deepwater Horizon rig explosion. The scientists compared the chemical composition of the waters, as well as their microbial cell populations.
Despite the hostile environment, they found that the density of microbial cells inside the plume was twice that of uncontaminated water. The population was diverse, but certain types known to metabolize hydrocarbons using ambient oxygen and thrive in the presence of oil in cold water were particularly plentiful.
The authors of the paper found that, on average, the microbes were consuming hydrocarbons fast enough to give the plume's oil a half life of one to six days. The metabolization isn't yet taxing the water too badly, either, as the oxygen concentration inside the plume is only eight percent lower than normal, a figure consistent with other recent results.
Several factors contribute to the easy digestibility of the plume, including the fact that it's relatively light, dispersed, and composed mostly of the volatile stuff that the microbes love to eat. The microbes have also had lots of oil-eating practice from slower natural seeps in the area. This doesn't mean our troubles are over—many other toxic materials from the oil, such as methane, may persist. Still, it appears the bacteria may be able to pick up some of our deep-ocean-cleaning slack.
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