Washington, October 1 : A new research has revealed that subsurface life in the form of single-celled organisms feast on an extensive number of oil compounds.
The research, led by David Valentine of UC (University of California) Santa Barbara and Chris Reddy of Woods Hole Oceanographic Institution in Massachusetts, was conducted thousands of feet below the bottom of the sea, off the shores of Santa Barbara in the US.
They detail how the microbes are dining on thousands of compounds that make up the oil seeping from the sea floor.
"It takes a special organism to live half a mile deep in the Earth and eat oil for a living," said Valentine, an associate professor of earth science at UCSB. "There's this incredibly complex diet for organisms down there eating the oil. It's like a buffet," he added.
The researchers found that there may be one other byproduct being produced by all of this munching on oil - natural gas.
"They're eating the oil, and probably making natural gas out of it," Valentine said. "It's actually a whole consortium of organisms - some that are eating the oil and producing intermediate products, and then those intermediate products are converted by another group to natural gas," he added.
Reddy, a marine chemist at Woods Hole, said that the research provides important new clues in the study of petroleum.
"The biggest surprise was that microbes living without oxygen could eat so many compounds that compose crude oil," he said.
"Prior to this study, only a handful of compounds were shown, mostly in laboratory studies, to be degraded anaerobically. This is a major leap forward in understanding petroleum geochemistry and microbiology," he added.
According to Valentine, the diet of the single-cell microbes is far more diverse than previously thought.
"They ate around 1,000 of the 1,500 compounds we could trace, and presumably are eating many more," he said.
By studying samples from the subsurface, the ocean floor, the mid-water, and then from the surface, the researchers could determine how much of the oil was being degraded and digested by the microbes.
Using a new technique devised by Reddy, the scientists were able to pick apart the differences in the makeup of the oil, which is migrating 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 and, sometimes, to the beaches in the form of tar.