by Medindia Content Team on  November 23, 2007 at 1:37 PM Environmental Health
Methane-consuming Bug Could Be a Natural Way to Fight Methane Emissions
A methane-consuming microorganism discovered in geothermal areas in Rotorua, New Zealand, could, one day, be used to reduce methane gas emissions from landfills. It could also help cut methane emissions from geothermal power stations.

A geothermal area is an area where warm water ascends through fissures, crevices and volcanic crust. Cold rainwater pours down into the porous bedrock, is heated from the old magma chamber and fissures and ascends to the surface as it gets hotter. Magma is simply molten rock located beneath the surface of the earth.

The science journal Nature has just published a paper on the microorganism, which was discovered in soil at Tikitere geothermal field, also known as Hell's Gate, near Rotorua, New Zealand by researchers at GNS Science.

Climate researchers are expected to follow the discovery closely as the bacterium offers the potential to reduce the amount of methane entering the atmosphere. Methane is a far more potent greenhouse gas than carbon dioxide.

The "greenhouse effect" is the heating of the Earth due to the presence of greenhouse gases. It is named this way because of a similar effect produced by the glass panes of a greenhouse. Shorter-wavelength solar radiation from the sun passes through Earth's atmosphere, then is absorbed by the surface of the Earth, causing it to warm. Part of the absorbed energy is then reradiated back to the atmosphere as long wave infared radiation. Little of this long wave radiation escapes back into space; the radiation cannot pass through the greenhouse gases in the atmosphere. The greenhouse gases selectively transmit the infared waves, trapping some and allowing some to pass through into space. The greenhouse gases absorb these waves and reemits the waves downward, causing the lower atmosphere to warm.

Estimates suggest that about a third of current annual methane emissions come from wetlands, forest and grass fires, oceans, and other natural sources.

The remaining two-thirds reportedly come from the production and transportation of oil and natural gas, coal mining, rotting landfills, sewage, belching livestock, and other human-influenced sources.

The hardy bacterium discovered in New Zealand is part of a group known as methanotrophs, but this one is able to live in hotter and much more acidic conditions than its relatives.

Methanotrophs use methane as their only source of energy. They live mostly in soils and are especially common in environments where methane is produced.

Microbiologist at GNS Science, Matthew Stott, said it was a particularly exciting discovery as it had international significance.

"We knew methane was being produced geothermally at Hell's Gate and we were puzzled as to why it wasn't reaching the surface," Dr Stott said.

"What we have found is an extremely tough methane-consuming organism that is new to science. It grows happily under extremely acidic conditions in the lab."

Globally, acidic environments such as marshes and peat bogs generate significant quantities of methane. Scientists have always suspected that a proportion of this methane was being consumed by bacteria living in these environments.

"Our discovery has demonstrated that methane-consuming organisms do live in highly acidic environments. Without them, the amount of methane entering the atmosphere would be much greater.

"Ultimately, it may be possible to implant this organism, or a similar one, in landfills and cut methane emissions into the atmosphere."

GNS Science worked with colleagues at the University of Hawaii to sequence the genome of the bacterium. They found its genetic makeup was different to all known methanotrophic organisms.

The discovery stems from a collaboration between GNS Science and the owner and operator of Hell's Gate, Tikitere Trust. The agreement between the two organisations includes the sharing of any benefits that might accrue from scientific discoveries.

Spokesman for Tikitere Trust, Jim Gray, said the discovery had the potential to put New Zealand and Tikitere Trust at the leading edge of extremophile science internationally.

"The Trust sees this is an exciting development that has both commercial and scientific implications for New Zealand."

Source: Medindia

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