

In the hot, dark water of a South African mine, scientists have found the world's loneliest species.

Everywhere else biologists have studied life on our planet, they've found communities of life, but today, biologists announced they have discovered an ecosystem that contains just a single species of bacteria.

In all other known ecosystems, the key functions of life – harvesting energy and elements like carbon and nitrogen from the environment – have been shared among different species. But in the water of the Mponeng gold mine, two miles under the earth's surface, Desulforudis audaxviator carries out all of those functions by itself. In short, it's the tidiest package of life found yet.

"It is possible to pack everything necessary for maintaining life into one genome," said Dylan Chivian of Lawrence Berkeley National Laboratory.

All known life forms need carbon, hydrogen, nitrogen and an energy source to live. Plants need nitrogen, but can't just pull it from the atmosphere and start using it to make amino acids. Instead, they rely on archaea for that task. Interconnections like these form the basis of an ecosystem, often cheesily called the 'web of life'.

What makes D. audaxviator so special is that its genome, cobbled together from bacterial and archaeal genes, can carry out all life's functions by itself.

That could make the bug a prime candidate for any attempt to see if Earth's microbes could live in some other extreme environment within the solar system.

"Since it could live on its own on Earth, if it were given a matching habitat elsewhere, it could live," said Chivian.

Images: 1. Inside a tunnel in the Mponeng mine. Courtesy Anglo Gold. 2. D. audaxviator's genome annotated by Chivian. Courtesy Science.

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