Bacteria have been rapidly eating a long undersea plume of oil in the Gulf of Mexico. The plume was thought to contain up to 20% of the total oil spilled after the Deepwater Horizon blowout. Terry Hazen, a microbial ecologist with the Lawrence Berkeley National Laboratory, and his team published their research on these bacteria in the journal Science.

Terry Hazen: Soon after we got out there on May 25, we detected a signal for hydrocarbons – oil – down deep, at about 1,100 meters. It’s better to define it as a cloud instead of plume, because it was very diffuse, so in other words, very small droplets, 10 to 60 microns of oil.

Dr. Hazen said he suspected there might be oil-eating microbes around the plume, because the sea floor there has many natural seeps of oil.

Terry Hazen: Now according to Ian McDonald of Florida State University, there is the equivalent of two Exxon Valdez spills going into the Gulf of Mexico every year from natural seeps. And this has been going on for millions of years. So if I had to bet where I would find oil-degrading bacteria down deep, this would have been one of the spots. And indeed, we showed that.

Back in the lab, said Hazen, cloned samples of the newly discovered bacteria appear to be able to digest a quantity of oil half volume of the Gulf oil plume about every three days. They eventually break the oil down to CO2 and water, he said.

Terry Hazen: Now, did they degrade every single component of the oil? It’s doubtful. And there could be some long-term effects from some of these very, very low concentrations. We don’t know. That remains to be seen.

Hazen added that in September 2010 he and other scientists are digging into the sediments near the wellhead to look for more signs of what has happened to oil spilled in the Gulf of Mexico.

Terry Hazen: Some of the other investigators that were out there, and of course the week before last, a week before our paper came out, the Woods Hole group came out with a very good study, basically defining the plume, in terms of the oil hydrocarbons and that sort of thing, using some very sophisticated instrumentation. And they defined it very well.

The bacteria basically break down the oil into CO2 and water, said Hazen.

Terry Hazen: They can completely degrade it to carbon dioxide and water, basically. All of the components are there. And of course there’ll be some nitrogen compounds within the oil. But these will all be incorporated into the biomass.

Hazen described the funding behind his research, in part from British Petroleum, which leased the failed well responsible for the oil spill.

Terry Hazen: We are part of the DOE National Laboratory. The infrastructure and everything else that we do and all the special instruments and that sort of thing is funded by the Department of Energy. We also have funding in this case the Energy Biosciences Institute. This is a 500-million dollar grant that was competed for by the University of California, Berkeley, from BP, and it’s a ten-year grant, and it started about four years ago. And as part of that, we proposed a program in microbial-enhanced hydrocarbon recovery, or oil recovery, and we were using these same tools of molecular analysis from oil wells and petroleum reservoirs and oil, looking to see what microbes were present, and that sort of thing. So that actually enabled us to immediately refocus some of that work, and basically using the same techniques and that sort of thing. And of course, ultimately it was funded by BP, but our contracts run through the University of California at Berkeley and then come to the DOE National Lab at Lawrence Berkeley National Laboratory.