Loneliest, weirdest organism found
Friday, 10 Oct 2008 03:01
Desulforudis audaxviator lives 2.8km underground in absolute darkness
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Scientists have shed light on a unique microorganism that forms the world's only ecosystem with only one biological species.
The rod-shaped bacterium Desulforudis audaxviator lives 2.8km underground and survives in a habitat where it gets its energy not from the sun but from hydrogen and sulphate produced by the radioactive decay of uranium.
Living alone, D. audaxviator must build its organic molecules by itself out of water, inorganic carbon, and nitrogen from ammonia in the surrounding rocks and fluid.
During its long journey to the extreme depths, evolution has equipped the versatile spelunker with genes – many of them shared with archaea, members of a separate domain of life unrelated to bacteria – that allow it to cope with a range of different conditions, including the ability to fix nitrogen directly from elemental nitrogen in the environment.
American researchers, publishing their findings in the journal Science, found the bacterium in the Mponeng gold mine in Johannesburg.
"The great thing about environmental genomics is that it has made it possible to form a much more complete picture of microscopic life everywhere on Earth, instead of being limited to the very small proportion of bugs" – microorganisms, that is – "that can be cultured in the lab," said lead author Dylan Chivian of Berkeley Lab.
"Almost all organisms live in communities with subdivided roles within their ecosystems. By extracting DNA from environmental samples, the various players in these microbial communities and the abilities of their dominant members can be identified, even if complete genomes of most of them are impossible to sort out."