"Bold traveller" bug could be a 'goldmine' of clues to life on other planets
10 Oct 2008, 1245 Hrs

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London, Oct 10 A bug, discovered deep in a goldmine and nicknamed "the bold traveller" has got astrobiologists excited because of its unique ability to live in complete isolation of any other living species, suggesting it could be the key to life on other planets.

According to a report in New Scientist, a community of the bacteria Candidatus Desulforudis audaxviator has been discovered 2.8 kilometers beneath the surface of the Earth in fluid-filled cracks of the Mponeng goldmine in South Africa.

Its 60 degree Celsius home is completely isolated from the rest of the world, and devoid of light and oxygen.

Dylan Chivian of the Lawrence Berkeley National Laboratory, California, studied the genes found in samples of the fluid to identify the organisms living within it, expecting to find a mix of species.

Instead, he found that 99.9 percent of the DNA belonged to one bacterium, a new species. The remaining DNA was contamination from the mine and the laboratory.

"The fact that the community contains only one species stands one of the basic tenets of microbial ecology on its head," said Carl Pilcher, director of the NASA Astrobiology Institute.

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," said Pilcher.

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.

It also represents the kind or organism that could survive below the surface of Mars or Saturn's sixth largest moon Enceladus.

According to Chivian, "One question that has arisen when considering the capacity of other planets to support life is whether organisms can exist independently, without access even to the Sun."

"The answer is yes and here's the proof. It's philosophically exciting to know that everything necessary for life can be packed into a single genome," he added. (ANI)