Ancient microbe colonies found living under 800m ice in Antarctic

Written By Unknown on Kamis, 21 Agustus 2014 | 22.33

In a major breakthrough, scientists have finally proved that life exists in a lake buried under half a mile (800 meters) of ice on the west Antarctic ice sheet. Lake Whillans where 4000 types of micro-organisms were found has not seen sunlight or felt a breath of air for millions of years.

Many of the microbes are single-celled organisms known as Archaea, said Montana State University professor John Priscu, the chief scientist of the US project called WISSARD that sampled the sub-ice environment. The microorganisms that live beneath the enormous Antarctic ice sheet survive by converting ammonium and methane into the energy required for growth.

"It's the first definitive evidence that there's not only life, but active ecosystems underneath the Antarctic ice sheet, something that we have been guessing about for decades. With this paper, we pound the table and say, 'Yes, we were right,'' lead author Brent Christner said. The paper is published in the latest issue of Nature.

The Antarctic ice sheet covers an area 1 ½ times the size of the United States and contains 70% of earth's freshwater, and any significant melting can drastically increase sea level. Lake Whillans, one of more than 200 known lakes beneath the Antarctic Ice Sheet and the primary lake in the WISSARD study, fills and drains about every three years. The river that drains Lake Whillans flows under the Ross Ice Shelf, which is the size of France, and feeds the Southern Ocean, where it can provide nutrients for life and influence water circulation patterns.

Although he was not really surprised about the discovery, Priscu said he was excited by some of the details of the Antarctic find, particularly how the microbes function without sunlight at subzero temperatures and the fact that evidence from DNA sequencing revealed that the dominant organisms are Archaea, one of three domains of life, the others being Bacteria and Eukaryote.

Many of the subglacial archaea use the energy in the chemical bonds of ammonium to fix carbon dioxide and drive other metabolic processes. Another group of microorganisms uses the energy and carbon in methane to make a living.

According to Priscu, the source of the ammonium and methane is most likely from the breakdown of organic matter that was deposited in the area hundreds of thousands of years ago when Antarctica was warmer and the sea inundated west Antarctica.

The Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project officially began in 2009. The researchers drilled down to the lake in January 2013.

Christner said species are hard to determine in microbiology, but "We are looking at a water column that probably has about 4,000 things we call species. It's incredibly diverse."

http://timesofindia.indiatimes.com/followceleb.cms?alias=Montana State University,microbes,Lake Whillans,Archaea,Antarctic


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