Oil-eating microbe found in the Gulf of Mexico
Saturday, August 28, 2010
 A group of researchers led by Terry Hazen, a senior ecologist at the Lawrence Berkeley National Laboratory, have discovered a new species of microorganism. Hazen's team started research in May this year. Their findings were based on more than 200 samples collected from 17 deep-water sites in the Gulf of Mexico between May 25 and June 2. The new species is distinctive for its oil-consuming activity in a wide range of conditions, and is playing a role in depletion of oil spills in the area. Scientists had been puzzled by the disappearance of oil in the aftermath of the Deepwater Horizon oil spill in the Gulf of Mexico. Detailed maps were made on how the spilled oil went underwater and how far it was spread; however, some of it seemed to have disappeared. A grant from the Energy Biosciences Institute, and a partnership led by the University of California, Berkeley and the University of Illinois that is funded by a USD 500 million, 10-year grant from BP, was the basis for support of the research. The U.S. Department of Energy and the University of Oklahoma Research Foundation also supported it. The field study was conducted during the first week. As Hazen said, "We deployed on two ships to determine the physical, chemical and microbiological properties of the deepwater oil plume. The oil escaping from the damaged wellhead represented an enormous carbon input to the water column ecosystem and while we suspected that hydrocarbon components in the oil could potentially serve as a carbon substrate for deep-sea microbes, scientific data was needed for informed decisions." Sample analysis was eased because the researchers used the pocket-sized Berkeley Lab DNA sampler PhyloChip. It allowed researchers to detect the presence of thousands of species of bacteria in samples from a wide range of environmental sources, without the culturing procedures usually performed in a furnished lab workplace. With the device, Hazen and his co-researchers discovered that a dominant microbe, making up 90 percent of all the bacteria in the oil plume, is a new species, closely related to members of Oceanospirillales family, more specifically Oleispirea antarctica and Oceaniserpentilla haliotis. The previous works were measuring low levels of oxygen in certain areas to detect microbes activity. Researchers thought that increased activity would lead to more aerobic activities, such as breathing, which depletes the oxygen content in water. However, the newly discovered species doesn't seem to be consuming much oxygen from the water column. The study found that oxygen saturation outside the oil plume was 67-percent, while within the plume, it was 59-percent. By Terry Hazen's words, "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... There's not enough iron to form more of these enzymes, which would degrade the carbon faster but also consume more oxygen." Analysis of changes in the oil composition as the plume extended from the wellhead pointed to faster than expected biodegradation rates with the half-life of alkanes ranging from 1.2 to 6.1 days. This microbe thrives in cold water, with temperatures in the deep recorded at 5 degrees Celsius (41 Fahrenheit). The summer observations showed the bacteria managed to consume the oil spill relatively quickly in June. Some commenters noted that the previously released oil dispersant COREXIT can have significantly eased the process of interaction of the microbes with the oil by making oil particles smaller and easier to access. As Hazen explained, "We've been out there continuously... Once the oil flow stopped on July 15, within two weeks we saw most of the plume disappear." |
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