Undersea Microbes Active But Living On The Slow Side

[phantom power]

This might have implications for theories about increased methane uptake by anaerobic bacteria, although none of these bacteria has access to atmospheric methane.

Deeply buried ocean sediments may house populations of tiny organisms that have extremely low maintenance energy needs and population turnover rates of anywhere from 200 to 2,000 years, according to an international team of researchers.

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"The samples showed strikingly elevated concentrations of cells in deeply buried sulfate-methane transition zones," says Dr. Christopher H. House, assistant professor of geosciences, Penn State. "Sulfate methane transition zones are areas where both methane and sulfate diffuse and both compounds are used by local denizens."

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Besides simply knowing that populations of Archaea exist in the deep sediment layers at the sulfate-methane transition zones, the researchers looked at the energy sources for these microbes. Many organisms living in environments with methane use the methane for energy and use the methane's carbon to grow, repair and reproduce. Looking at the carbon isotopes the researchers found that few if any of these Archaea used methane as a carbon source. They also found that conversion of carbon dioxide to methane was not fueling these Archaea.

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In fact, the researchers estimate that these Archaea may completely turn over population as frequently as every 70 years, or as infrequently as 2,150 years. They also suggest that the sulfate-methane transition zone is a much better environment than other areas in the sediment and that turnover rates are even lower away from the transition zone.

http://www.sciencedaily.com/releases/2006/04/060410163558.htm