March 30, 2009

Microbes emit methane without hydrogen gas

U.S. scientists say they've discovered microbes can directly convert carbon dioxide and water to methane without generating hydrogen.

Pennsylvania State University Professor Bruce Logan said his team made the discovery while studying making hydrogen in microbial electrolysis cells.

We kept getting all this methane, he said. We may now understand why.

Methanogenic microorganisms produce methane in marshes and dumps but scientists thought the organisms turned hydrogen or organic materials, such as acetate, into methane. However, the researchers found the cells produced much more methane than expected.

All the methane generation going on in nature that we have assumed is going through hydrogen may not be, said Logan. We actually find very little hydrogen in the gas phase in nature. Perhaps where we assumed hydrogen is being made, it is not.

He said microbial electrolysis cells require an electrical voltage to be added to the voltage that is produced by bacteria using organic materials to make current that evolves into hydrogen. The researchers found the Archaea, using about the same electrical input, could use the current to convert carbon dioxide and water to methane without any organic material, bacteria or hydrogen usually found in microbial electrolysis cells.

The study was reported in the journal Environmental Science and Technology.