A newly discovered type of oil-eating microbe suddenly is flourishing in the Gulf of Mexico and gobbling up the BP spill at a much faster rate than expected, scientists reported Tuesday.
Scientists discovered the new microbe while studying the underwater dispersion of millions of gallons of oil spilled since the explosion of BP's Deepwater Horizon drilling rig.
Also, the microbe works without significantly depleting oxygen in the water, researchers reported in the online journal Sciencexpress.
"Our findings ... suggest that a great potential for intrinsic bioremediation of oil plumes exists in the deep-sea," lead researcher Terry Hazen, a microbial ecologist at Lawrence Berkeley National Lab in Berkeley, California, said in a statement.
The data is also the first ever on microbial activity from a deep-water dispersed oil plume, Hazen said.
Environmentalists have raised fears about the giant oil spill and the underwater plume of dispersed oil, particularly its potential effects on sea life. A report just last week described a 22-mile-long underwater mist of tiny oil droplets.
"Our findings show that the influx of oil profoundly altered the microbial community by significantly stimulating deep-sea" cold temperature bacteria that are closely related to known petroleum-degrading microbes, Hazen reported.
Their findings are based on more than 200 samples collected from 17 deep-water sites between May 25 and June 2. They found that the dominant microbe in the oil plume is a new species, closely related to members of Oceanospirillales.
This microbe thrives in cold water, with temperatures in the deep recorded at 41 degrees Fahrenheit.
Hazen suggested that the bacteria may have adapted over time due to periodic leaks and natural seeps of oil in the Gulf.
Scientists also had been concerned that oil-eating activity by microbes would consume large amounts of oxygen in the water and create a "dead zone" dangerous to other life. The new study found that oxygen saturation outside the oil plume was 67 percent while within the plume it was 59 percent.
"The low concentrations of iron in seawater may have prevented oxygen concentrations dropping more precipitously from biodegradation demand on the petroleum, since many hydrocarbon-degrading enzymes have iron as a component," Hazen said. "There's not enough iron to form more of these enzymes, which would degrade the carbon faster but also consume more oxygen."
These latest findings may initially seem to be at odds with the study published last Thursday in Science by researchers from Woods Hole Oceanographic Institution, which confirmed the existence of the oil plume and said microorganisms did not seem to be biodegrading it very quickly.
However, Hazen and Rich Camilli of Woods Hole both said Tuesday that the studies complement each other.
The Woods Hole team used a robot submarine and a mass spectrometer to detect the plume, but were forced to leave the area in late June, when Hurricane Alex threatened. At that time, they figured the plume was likely to remain for some time.
But that was before the well was capped in mid-July. Hazen said that within two weeks of the capping, the plume could not be detected, but there was a phenomenon called marine snow that indicated microbes had been feasting on hydrocarbons.
As of Tuesday, there was no sign of the plume, Hazen said.
That doesn't mean there is no oil left from the 4.9 million barrels of crude that spilled into the Gulf after the April 20 blowout at BP's Deepwater Horizon rig. The U.S. government estimated on Aug. 4 that 50 percent of the BP oil is gone from the Gulf and the rest is rapidly degrading.
The research was supported by an existing grant with the Energy Biosciences Institute, a partnership led by the U.C. Berkeley and the University of Illinois that is funded by a $500 million, 10-year grant from BP. Other support came from the U.S. Department of Energy and the University of Oklahoma Research Foundation.
Sciencexpress is the online edition of the journal Science.