AN IMPROBABLE microbe, , has been glimpsed half a world away in California.
Desulforudis audaxviator was found in water-filled fractures in South Africa’s deep gold mines, where it lives isolated from every other life form on Earth. Uniquely, the bacterium has evolved to do without the sun’s energy, relying only on hydrogen and sulphate.
Now, a project to map Earth’s deep biosphere has found 99 per cent identical DNA tens of thousands of kilometres away, in boreholes 900 metres deep near Death Valley in eastern California.
Advertisement
Duane Moser at the Desert Research Institute in Las Vegas, Nevada, discussed the find at the in San Francisco on 6 December. “We’re reasonably sure we’re looking at the same bug,” he says.
If so, D. audaxviator – literally, “bold traveller” – merits its name. If the bacterium came from South Africa, it probably started out at shallow depths and evolved to live in ever-greater isolation as it descended, says Moser. Some bacteria may have made the return journey and reached the surface, perhaps through water springs. From there they may have surfed the winds before raining down on the US and begun to descend once more.
“We’re taught in school that all life needs some input from the sun,” says Moser. “What we’re seeing in D. audaxviator is that even where the sun hasn’t shone for hundreds of millions of years – like the interior of Earth or Mars – life can find a way.”
