| Subject: Microbes in permafrost |
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Blobrana
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Date Posted: 11:32:39 02/23/05 Wed
Microbes in the Alaskan permafrost have been found living in temperatures as low as minus 40 degrees Celsius.
The discovery raises concerns that the activity of these bacteria, once thought inactive at such extreme temperatures, could be making a considerable contribution to greenhouse gas production. Scientists found that bacteria taken from the Alaskan tundra soil release gases during energy production whilst apparently in a frozen state.
This runs contrary to textbook biology, which dictates the need for freely available water to allow these single-celled life forms to function.
Dr Nicolai Panikov, from the Stevens Institute of Technology, New Jersey, US, and colleague, Dr Vladimir Romanovsky, from the University of Alaska, tested the mixture of bacteria and registered the production of gases; by-products of metabolism.
"Typically, bacteria in the permafrost are in a dormant state but we have found that they reproduce very slowly and respire, producing gases including CO2 and methane when frozen." - Dr Panikov .
Water is considered essential for life, whether at the single-cell level, such as in bacteria, or in larger animals. It helps the exchange of essential gases between the bacteria and the outside. So the discovery of bacteria, thought to be frozen solid at such extreme temperatures, raises many interesting questions about the survival mechanisms used in these harsh conditions.
"We have found that it is not pure ice but the mixture of ice and mineral particles that allows for the exchange of gases”
"One explanation is that the bacteria oxidise substances in the permafrost to generate heat inside them or that these microbes create anti-freeze compounds that keep water liquefied inside their cells."
Permafrost covers about one fifth of the world's land surface and is frozen over most of Alaska, Northern Canada and Siberia, from depths of a few centimetres to 300m. Long considered a major carbon sink, recent evidence suggests that the permafrost is thawing as global temperatures rise. Even a small increase in temperature will have a significant increase on the rate of metabolic activity in these bacteria affecting the biochemistry of the soil.
If the activity of these bacteria was incorporated into models of climate change prediction, the permafrost may take on the role of a source of greenhouse gases rather than a sink.
"Our results predict the rate of actual degradation- it shows that it's not necessary for the temperature to rise to freezing point for the stimulation of the degradation process."
Knut Stamnes, Professor of atmospheric physics at Stevens, believes that as the permafrost thaws the greatest threat comes from methane.
"Methane is more important than CO2 in producing greenhouse gases because the atmosphere is relatively saturated with CO2 but not with methane yet. This is a new area for exploration."
<a rel=nofollow target=_blank href="http://www.stevensnewsservice.com/pr/pr523.htm">http://www.stevensnewsservice.com/pr/pr523.htm</a>
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