Robin says: "This news does it for me; much more likely than not, life on Earth came from life elsewhere."

A bug discovered deep in a goldmine and nicknamed "the bold traveller" has got astrobiologists buzzing with excitement. Its unique ability to live in complete isolation of any other living species suggests it could be the key to life on other planets. . .

"The fact that the community contains only one species stands one of the basic tenets of microbial ecology on its head," says Carl Pilcher, director of the NASA Astrobiology Institute, who was not involved in Chivian's DNA analysis but whose team made the initial discovery that there were microbes living in this particular fissure two years ago.

Evolutionary biologist E. O. Wilson says the discovery is so important he will at once begin to mention it in his lectures on biodiversity.

That's from an article Robin linked. This is the part that I find fascinating.

A community of a single species is almost unheard of in the microbial world. It means the ecosystem's only species must extract everything it needs from an otherwise dead environment.

"Virtually all other known ecosystems on Earth that don't use sunlight directly do use some product of photosynthesis," says Pilcher.

Deep-sea vent communities, for instance, are too far down to directly use sunlight but they do use oxygen dissolved in seawater, and that oxygen is produced by photosynthesising plankton at the surface.

Chivian's analysis shows that D. audaxviator gets its energy from the radioactive decay of uranium in the surrounding rocks. It has genes to extract carbon from dissolved carbon dioxide and other genes to fix nitrogen, which comes from the surrounding rocks. Both carbon and nitrogen are essential building blocks for life as we know it, and are used in the building blocks of proteins, amino acids. D. audaxviator has genes to produce all the amino acids it needs.

D. audaxviator can also protect itself from environmental hazards by forming endospores – tough shells that protect its DNA and RNA from drying out, toxic chemicals and from starvation. It has a flagellum to help it navigate.

How does such a self-reliant species come to exist?

Some of the bacterium's genes appear to be inherited from a related species. Others have been found in archaea, a group of organisms evolutionarily distinct from bacteria. Chivian says D. audaxviator may have evolved as it travelled down through the cracks in the rock, and acquired archaea genes through horizontal gene transfer from populations it crossed on its way down.

"It can't handle oxygen," he says. This suggests it has not been exposed to pure oxygen for a long time. The water in which D. audaxviator lives has not seen the light of day in over 3 million years, and this could be an indication of how old the species is.

Will wonders never cease?