Saturday, February 9, 2008

Extremophile Hunt Begins in Antarctica, Implications for Exobiologists

Written by Ian O'Neill

The extremophile bacteria Spirochaeta americana (credit: NASA)
An expedition has set off for Antarctica's Lake Untersee in the quest to find bacteria living in one of the most extreme environments on Earth. The bacteria-hunting team are looking for a basic lifeform in a highly toxic location. Resembling the chemistry of Mars, moons of Jupiter and Saturn, even comets, the ice-covered lake may hold some clues to how life might survive, thrive even, beyond the "normality" of our planet.

Lake Untersee is a strange place. For starters, it is always covered in ice. Secondly, the water's pH level is so alkali that it resembles bleach rather than regular lake water. And third, it produces methane on a scale that dwarfs any other source on Earth. In fact, the chemistry of this terrestrial location has been likened to the high alkalinity, high methane environments on Mars, frozen moons and comets in our solar system neighborhood.

We already know that extreme life can thrive in the superheated conditions along volcanic vents in the oceans and they can live quite happily in nuclear reactors. Some bacteria are content to be frozen for over 30,000 years before they are thawed to continue life as if nothing had happened. So the search continues… can life thrive in conditions where the pH (a measure of a substances acidity or alkalinity) is considered to be toxic to life? The head scientist of the Antarctic team, Richard Hoover of NASA's Marshall Space Flight Center, believes that although we consider life that we know to thrive in the "normal" conditions we know and experience ourselves, this may not be the "norm" for life elsewhere in the cosmos.

The team of US, Russian and Austrian scientists hope to identify additional extreme bacteria to add to their impressive accolade of discoveries. So far, previous teams headed by Hoover have found new species and genera of anaerobic microbial extremophiles in the ice and permafrost of Alaska, Siberia, Patagonia, and Antarctica. Now they hope to find life that is hardy enough to deal not only with the extreme cold of the Antarctic, but also with the "normally" poisonous pH and high methane in Lake Untersee. This will characterize the signature of extreme life, a great help to exobiologists when results come in from future life-hunting missions to Mars and other planetary bodies.

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