Newly-discovered bacteria can use poison to live

WASHINGTON - The discovery of a strange bacteria that can use arsenic as one of its nutrients widens the scope for finding new forms of life on Earth and possibly beyond.

While researchers discovered the unusual bacteria on Earth, they say it shows that life has possibilities beyond the major elements that have been considered essential.

"This organism has dual capability. It can grow with either phosphorous or arsenic. That makes it very peculiar, though it falls short of being some form of truly 'alien' life," said Paul C. W. Davies of Arizona State University, a co-author of the report appearing in yesterday's online edition of the journal Science.

Six major elements have long been considered essential for life - carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. But the researchers found that the bacteria, discovered in Mono Lake, Calif., is able to continue to grow after substituting arsenic - which has long been used as a poison - for phosphorous.

"It makes you wonder what else is possible," said Ariel D. Anbar of Arizona State University, a co-author of the report.

The find is important in the search for life beyond Earth because researchers need to be able to recognize life, to know what life looks like, Anbar said.

The study focuses on a microbe found on Earth. However, the announcement of a news conference to discuss the find generated widespread speculation on the Internet that the report would disclose the discovery of extraterrestrial life.

The discovery "does show that in other planetary environments organisms might be able to use other elements to drive biochemistry and that the 'standard' set of elements we think are absolutely necessary for life might not be so fixed," said Charles Cockell, professor at the Planetary and Space Sciences Research Institute in Milton Keynes, United Kingdom. Cockell was not part of the research team.

"This work is novel because it shows the substitution of one element for another in fundamental biochemistry and biochemical structure," added Cockell. - AP