Russian scientists drilling deep into the ancient Lake Vostok in Antarctica thought they had found a new species of bacteria last week, but have recently announced all they had was just a contaminated sample.
The team had been drilling through the ice for more than 20 years before it finally reached the surface of the isolated lake and brought back water samples, buried under two miles of Antarctic ice. Scientists think the lake has been isolated from the surface of the Earth for as long as 25 million years.
They had high hopes it might reveal some previously unknown species of life — one that's been evolving without access to sunlight or energy sources from the surface of the Earth.
Last week, in a tiny sample of fresh lake water, they thought they had something: A strain of bacteria with DNA that did not resemble any other bacteria they could find in global data banks.
They quickly announced they had found a new species of life through the Russian state-owned news service, RIA Novosti. Their "mystery" life was about an 86 percent match with known organisms.
But they spoke too soon.
It turned out that that the reason it did not resemble anything was that it was just incomplete DNA from a contaminant — pieces of DNA from microorganisms that came from the lab environment, the researchers, or even the kerosene used to drill down into the ice.
Mix and match pieces from the different contaminating bacteria could have made it look like a new species when the sequences were searched together.
This setback does not mean there isn't any life in the lake. Scientists found specimens of bacteria and other microorganisms as they slowly drilled through the ice to the lake. These discoveries have led them to believe that there may be life down in the lake itself.
An American team has discovered bacteria in another subglacial lake in Antarctica called Lake Whillans last February.
Russian scientists will take more samples of the fresh water in the next few months using equipment specially designed to extract pure water samples.
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