Life, but not as we know it . . . bacterium thrives on poison
A strange, salty lake in California has yielded an equally strange bacterium that thrives on arsenic and redefines life as we know it, researchers reported yesterday.
The bacteria do not merely eat arsenic -- they incorporate the toxic element directly into their DNA, the researchers said.
The findings, published in 'Science', show just how little scientists know about the variety of life forms on Earth, and may greatly expand where they should be looking for life on other planets and moons, the NASA-funded team said.
"Life as we know it requires particular chemical elements and excludes others," Ariel Anbar of Arizona State University said in a statement. "But are those the only options? How different could life be?"
Mr Anbar, Felisa Wolfe-Simon of the NASA Astrobiology Institute and colleagues found the strain of Halomonadaceae in California's Mono Lake, formed in a volcanic region and very dense in minerals, including arsenic.
The researchers grew microbes from the lake in water loaded with arsenic, and only containing a little bit of phosphorus.
The GFAJ-1 strain of the Halomonadaceae grew when arsenic was in the water and when phosphorus was in the water, but not when both were taken away.
"This organism has dual capability," Paul Davies of NASA and Arizona State said in a statement.
"It can grow with either phosphorous or arsenic. That makes it very peculiar."
The finding suggests that astrobiologists looking for life on other planets do not need to look only for planets with the same balance of elements that Earth has.