is life possible without oxygen? As far as a particular kind of bacteria are concerned, the answer is an unambiguous yes, according to scientists of the Princeton University, us. In a paper published in the October 20 issue of Science (Vol 314, No 5798), scientists have revealed that a bacteria is surviving 2.8 km below the earth's surface without oxygen, sunlight and in extreme conditions of temperature and pressure.

The community of bacteria derives energy from the decay of radioactive rocks. This is the first group of microbes known to depend exclusively on geologically produced hydrogen and sulphur compounds from the groundwater for nourishment. The extreme conditions under which the bacteria live, resemble those of early earth, potentially offering insight into the nature of organisms that lived long before the Earth had an oxygen atmosphere.

Life in Mars? The find has also increased the possibility of existence of life elsewhere in the solar system, particularly in oxygen-deficient planets like the Mars. "The organisms have thrived in conditions considered inhospitable to life. Could these bacterial communities sustain themselves no matter what happened on the surface?' says Tullis Onstott, a Princeton University professor of geosciences and leader of the research team."What excites me is the possibility of life in Mars,' he says.

Discovering a new water-filled fracture inside a South African gold mine near Johannesburg, the scientists decided to study subsurface rock uncontaminated by human activities. They descended the hot, gas-choked shafts of the mine to find water seeping from the crack. "The environment we sampled would be much like the Kolar Gold fields