Life discovered in Antarctic lake 800 metres below the ice

These single-celled organisms live without sunlight in sub-zero temperatures. 

For the first time, scientists have discovered a thriving microbial ecosystem in one of Antarctica’s subglacial lakes, 800 metres beneath the west Antarctic ice sheet.

The team co-led by John Priscu of Montana State University in the US found 4,000 species of metabolically active, single-celled organisms (bacteria and archaea) after drilling into Lake Whillans.

"Our discovery proves that water is habitable space, even if it's at sub-zero temperatures and there is no sunlight," Priscu told New Scientist.

The water containing life was collected on 28 January, 2013 after six years of pain-staking work creating safe sampling procedures, and negotiating the difficult terrain, which presented unique logistic challenges.

The study was published in Nature 20 August 2014. 

The discovery is fantastic news for astrobiologists searching for life in the solar system. If bacteria can thrive deep beneath the surface of Antarctica, then maybe it can exist on the frozen surface of Jupiter's moon Europa or on Mars.

Scientists have been aware of the liquid water beneath the Antarctic ice sheet for more than 40 years, but it was only relatively recently that scientists began investigating for signs of life. 

The drilling was conducted using sterile hot water with filters, heating, ultraviolet light and hydrogen peroxide to ensure that no contaminates made it into the sample. 

A Russian team that drilled down to a lake in 2012 used non-sterile kerosene as the drilling liquid, which raised concerns that their samples were contaminated.

The scientists drilling at Lake Whillans found 130,000 microorganisms in each millilitre of water. This is a density similar to deep oceans or low-nutrient lakes. 

"We were surprised by the cell densities we observed," Priscu's colleague Brent Christner of Louisiana State University in the US told New Scientist.

The organisms survive without sunlight by converting ammonium to nitrite or by feeding off methane. 

Scientists concluded that the organisms must have been surviving without energy from the Sun for between 120,000 and one million years.

The team hopes to find multicellular life such as rotifers, worms or tardigrades in the future. The air bubbles over the lakes mean that oxygen is not a limiting factor but the low rate of carbon fixation by microbes is a concern