Two miles underground, strange bacteria are foun...( A Princeton-led research group has dis...)

A Princeton-led research group has discovered an isolated community of bacteria nearly two miles underground that derives all of its energy from the decay of radioactive rocks rather than from sunlight. According to members of the team, the finding suggests life might exist in similarly extreme conditions even on other worlds.

The self-sustaining bacterial community, which thrives in nutrient-rich groundwater found near a South African gold mine, has been isolated from the Earth's surface for several million years. It represents the first group of microbes known to depend exclusively on geologically produced hydrogen and sulfur compounds for nourishment. The extreme conditions under which the bacteria live bear a resemblance to those of early Earth, potentially offering insights into the nature of organisms that lived long before our planet had an oxygen atmosphere.

The scientists, who hail from nine collaborating institutions, had to burrow 2.8 kilometers beneath our world's surface to find these unusual microbes, leading the scientists to their speculations that life could exist in similar circumstances elsewhere in the solar system.

"What really gets my juices flowing is the possibility of life below the surface of Mars," said Tullis Onstott, a Princeton University professor of geosciences and leader of the research team. "These bacteria have been cut off from the surface of the Earth for many millions of years, but have thrived in conditions most organisms would consider to be inhospitable to life. Could these bacterial communities sustain themselves no matter what happened on the surface? If so, it raises the possibility that organisms could survive even on planets whose surfaces have long since become lifeless."

Onstott's team published its results in the Oct. 20 issue of the journal Science. The research group includes first author Li-Hung Lin, who performed many of the analyses as a doctoral student at Princeton and t
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Contact: Chad Boutin
cboutin@princeton.edu
609-258-5729
Princeton University
20-Oct-2006