Microbes in deep-sea rocks eat methane, lots of it

Most methane is buried deep in the ground. Some of it, however, bubbles up to escape, and that's good news for methane-loving microbes living in rocks that gather along the ocean's floor near methane sea vents, munching away on the colorless, odorless assembly of hydrocarbons.

The rocks host microbes that love a good methane buffet, especially one that goes bubbling by at all hours of the day. The microbes absorb the methane, converting it into energy and oxygen.

For the first time, scientists are beginning to grasp the impressive amounts of methane gas that never make it to the ocean's surface and up into the atmosphere -- all thanks to the appetite of tiny microbes living in tall stacks of carbonate rocks. This previously unrecognized biological sink for methane could have significant implications for how scientists understand the various processes affecting global warming.

"Methane is a much more powerful greenhouse gas than carbon dioxide, so tracing its flow through the environment is really a priority for climate models and for understanding the carbon cycle," study leader Victoria Orphan, a professor of geobiology at Caltech, said in a recent press release.

"We've recognized for awhile that the deep ocean is a sink for methane, but primarily it has been thought that it was only in the sediment," study co-author Jeffrey Marlow, a grad student at Caltech, told LiveScience. "The fact that it appears to be active in the rocks itself sort of redistributes where that methane is going."

Orphan, Marlow and their research partners even found these microbes living deep inside of carbonate rocks, not just on the surface. And although these bacteria cells convert methane to oxygen at roughly one-third the rate that microbes living in the ocean floor sediment do, there are many more rock microbes than there are sediment microbes -- meaning, according to Marlow, "their contributions to methane removal from the environment may be more significant."

The work of Orphan, Marlow and the rest of their team was detailed this week in the journal Nature Communications.