Tuesday, February 12, 2013

Life under ice

In Nature this week:
Lake-drilling team discovers life under the ice
Host of microbes found in lake deep under Antarctica's ice sheet.

The lake in question is a 60-square-kilometre body of water that sits on the edge of the Ross Ice shelf in West Antarctica. To reach it, Priscu, a glaciologist at Montana State University in Bozeman, and his team had to drill down 800 metres of ice.
Both water and sediment contained an array of microbes that did not need sunlight to survive. The scientists counted about 1,000 bacteria per millilitre of lake water — roughly one-tenth the abundance of microbes in the oceans. In Petri dishes, the bacteria show a “really good growth rate”, says Priscu.

The exact nature of the life unearthed by the US team will now be established by DNA sequencing and other tests. It will take at least a month to do the basic work, says Priscu.

“What we are all dying to find out now is, of course, ‘who’s there’ and ‘what’s their life style',” he says.

Researchers hope that the survival strategies of the subglacial microbes might offer clues to what the biology of extraterrestrial life might be like — Jupiter’s moon Europa, for instance, is thought to host a large sub-surface ocean of water where such life might be able to exist.

As photosynthesis is impossible without sunlight, the Lake Whillans bacteria must get their energy from a different source. This could be existing organic material, or, like the ‘chemotrophs’ found in gold mines and near deep-sea hydrothermal vents, the bacteria might run on chemical reactions involving minerals in the Antarctic bedrock and carbon dioxide dissolved in lake water.

“We have been allowed a glimpse into Antarctica’s subglacial world,” Priscu says. “I’m sure our results will change the way we view that continent.”

No comments: