A BACTERIUM that digests methane is doing its bit to slow global warming, say the American, German and Russian researchers who discovered it. But they warn that the bacterium-the first of its kind to be found in acidic wetlands-is being poisoned by industrial pollutants.

"The bacterium is a real novelty in two ways," says Werner Liesack, a team member from the Max Planck Institute for Terrestrial Microbiology in Marburg. It is unrelated to other methane-eating bacteria, and it thrives in acidic conditions.

Although most of the bacteria that produce methane live in acidic wetlands in the northern hemisphere, these environments were thought to be unsuitable for bacteria that digest the gas. But the scientists noticed that some wetlands in Europe were only producing about half as much methane as expected-and this led them to the bacterium.

"It plays a vital role in protecting the atmosphere," says Liesack. Almost half the world's methane emissions come from wetlands in the northern hemisphere.

The bacterium is under threat, however. Nikolai Panikov and Svetlana Dedysh of Moscow University found that it is especially sensitive to nitrate and sulphate pollution from industry and traffic. They say that the methane output of acidic wetlands is now higher than it was before the industrial revolution, because of the decline in this methane-eating bacterium. The team, whose research has yet to be published, is still deciding what to call it.

Author: Oliver Klaffke
New Scientist magazine, issue 20 March 99

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