Oct 8, 2007

100,000 years on ice, and no freezer burn

Microbes are hardy little creatures, NewScientist reports:
Microbes can survive trapped inside ice crystals, under 3 kilometres of snow, for more than 100,000 years, a new study suggests. The study bolsters the case that life may exist on distant, icy worlds in our own solar system.

Living bacteria have been found in ice cores sampled at depths of 4 kilometres in Antarctica, though some scientists have argued that those microbes were contaminants from the drilling and testing of the samples in labs. And in 2005, researchers revived a bacterium that sat dormant in a frozen pond in Alaska for 32,000 years (see Ice age bacteria brought back to life).

Now, physicist Buford Price and graduate student Robert Rohde, both at University of California in Berkeley, US, have found a mechanism to explain how microbes could survive such extreme conditions.

They say a tiny film of liquid water forms spontaneously around the microbe. Oxygen, hydrogen, methane and many other gases will then diffuse to this film from air bubbles nearby, providing the microbe with sufficient food to survive.

Thus, virtually any microbe can remain alive in solid ice, resisting temperatures down to -55° Celsius and pressures of 300 atmospheres.

Under such harsh conditions, the microbes would not be able to grow and reproduce, but they would still be able to repair any molecular damage, keeping themselves viable for more than a thousand centuries, the team says. "It is not life as we generally think about it," says Rohde. "[They] are just sitting there surviving, hoping that the ice will melt."
And waiting for the next great HBO series to replace The Sopranos.

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