A SPECIES of bacteria that has lain dormant in the Alaskan permafrost for 32,000 years has been revived. It is the first new species to be found in ancient ice, and its discoverers say that it adds weight to the idea that looking for frozen organisms on Mars is worthwhile.
The bacterium, discovered near Fox, Alaska, has been named Carnobacterium pleistocenium after the Pleistocene period when it was last loose. At the time woolly mammoths and sabre-toothed tigers were roaming the planet.
NASA astrobiologist Richard Hoover retrieved the bacteria from a tunnel in the Alaskan permafrost carved by the US Army鈥檚 Cold Regions Research and Engineering Laboratory.
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The bacteria came from a cross section of a preserved pond which had a brownish patch at the bottom that Hoover thought might be a collection of single-celled algae called diatoms. 鈥淚 was disappointed that there weren鈥檛 any,鈥� he says. Instead, he saw a host of bacteria that started swimming as soon as the ice melted.
Hoover took the samples back to the Marshall Space Flight Center in Huntsville, Alabama, and grew the bugs. Initially, his team thought the bacteria might be modern, but gene sequencing revealed it as an unknown species (International Journal of Systematic and Evolutionary Microbiology, vol 55, p 473).
Claims of reviving ancient bacteria have been made before. In 2000, researchers at West Chester University in Pennsylvania announced that they had isolated a 250-million-year-old bacterium from a salt deposit (New Scientist, 28 April 2001, p 36). But other scientists have been sceptical, saying it is doubtful that DNA could survive that long, or pointing out that the bacteria could be modern contaminants. 鈥淭he fact you have extracted microbes from the salt doesn鈥檛 really tell you the microbes are as old as the salt,鈥� says Robert Hazen, a geophysicist with the Carnegie Institution of Washington and president of the Mineralogical Society of America.
鈥淚 think the most important thing from this observation is that microorganisms can be preserved in ice for long periods of time,鈥� says Hoover. They may even be lurking on Mars.
