Study Reveals Microbes Dine on Thousands of Compounds in Oil

New research led by David Valentine of University of California at Santa Barbara (Santa Barbara, CA), Chris Reddy of Woods Hole Oceanographic Institution (WHOI) (Woodshole, MA), George Wardlaw, a graduate student in the Marine Science program at UCSB, and three other co-authors from Swiss Federal Institute of Technology and WHOI details how microbes are dining on thousands of compounds that make up the oil seeping from the sea floor. Research for this project began several years ago when Valentine brought Reddy out to the natural hydrocarbon seep field right off the California coast. Approximately 100 barrels of oil ooze out of the sea floor there each day and bubble up 15 meters to the sea surface.

Using a new technique devised by Reddy, the scientists were able to pick apart the differences in the makeup of the oil along its migration route to the surface through faults from deep below the sea floor. The microbes prefer the lighter compounds of oil. They tend to leave behind the heavily weathered residue, which is what makes its way to the surface. The samples were sent to Reddy's lab in Woods Hole to be analyzed using a diagnostic technology called a comprehensive two-dimensional gas chromatography ( GCxGC ), which cools the compounds to stop their motion for about 10 seconds, and a flash pulse of hot air releases them into a second column, where the compounds travel at different speeds, allowing the researchers to differentiate the many thousands of compounds.

According to Valentine, the next steps in their research are already under way. They are following the oil diet in controlled laboratory conditions, and tracking the fate of the oil once it forms a slick at the sea surface.