Scientists stunned by bacteria
Source: Agencies |
December 4, 2010, Saturday
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A STRANGE, salty expanse of water in California, called Mono Lake, has yielded an equally strange bacterium that thrives on arsenic and redefines life as we know it, researchers reported on Thursday.
The bacteria do not merely eat arsenic- they incorporate the toxic element directly into their DNA, said researchers.
The finding shows 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.
The study, published in the journal Science, shows that one of the most notorious poisons on Earth can also be the stuff of life for some creatures.
"Life is mostly composed of the elements carbon, hydrogen, nitrogen, oxygen, sulfur and phosphorus," the researchers wrote in Science.
These six elements make up the nucleic acids of DNA - as well as proteins and lipids. But there is no reason in theory why other elements should not be used. It is just that science never found anything alive that used them.
The researchers grew microbes from the lake in water loaded with arsenic, and only containing a little bit of phosphorus.
The bacteria grew when arsenic was in the water and when phosphorus was in the water, but not when both were taken away.
Howver, Paul Davies of NASA said the bacterium is not a new life form.
"It falls short of being some form of truly 'alien' life belonging to a different tree of life with a separate origin," he said.
But it does suggest that astrobiologists looking for life on other planets do not need to look only for planets with the same balance of elements as Earth has.
The bacteria do not merely eat arsenic- they incorporate the toxic element directly into their DNA, said researchers.
The finding shows 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.
The study, published in the journal Science, shows that one of the most notorious poisons on Earth can also be the stuff of life for some creatures.
"Life is mostly composed of the elements carbon, hydrogen, nitrogen, oxygen, sulfur and phosphorus," the researchers wrote in Science.
These six elements make up the nucleic acids of DNA - as well as proteins and lipids. But there is no reason in theory why other elements should not be used. It is just that science never found anything alive that used them.
The researchers grew microbes from the lake in water loaded with arsenic, and only containing a little bit of phosphorus.
The bacteria grew when arsenic was in the water and when phosphorus was in the water, but not when both were taken away.
Howver, Paul Davies of NASA said the bacterium is not a new life form.
"It falls short of being some form of truly 'alien' life belonging to a different tree of life with a separate origin," he said.
But it does suggest that astrobiologists looking for life on other planets do not need to look only for planets with the same balance of elements as Earth has.
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