Just days after Russian scientists announced that they had found a previously unidentified species of bacteria in Antarctica's subglacial Lake Vostok, the discovery has been called into question.
On 7 March, the St. Petersburg Nuclear Physics Institute's Sergei Bulat, who led the Russian team that drilled through 4 kilometers of ice to the surface of the lake last year, told Russian news agency RIA Novosti that they had found a previously unidentified species of bacteria  in lake samples collected during an expedition in January.
That they had found life at all was exciting and a reversal of the team's earlier stance from a decade ago that Vostok might be barren.
But on 9 March, the head of the genetics laboratory at the St. Petersburg Institute, Vladimir Korolyov, told Interfax that what the team had found was only contamination . "We found certain specimen, although not many, but all of them belonged to contaminants (microorganisms from the bore-hole kerosene, human bodies or the lab)," he said. "There was one strain of bacteria which we did not find in drilling liquid, but the bacteria could in principal use kerosene as an energy source. That is why we can't say that a previously-unknown bacteria was found."
Korolyov said that they would need to wait for pure water samples to determine what, if any, life might exist in Vostok—samples that the team hopes to have within the next year. "For now we'd rather not say something we will be unable to whitewash even with the crystal clear Vostok water."