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Bacterium Lives Without Phosphorus; May Alter Thinking On Life

There's lots of chatter on the cable channels and on the Web today about the news from NASA that researchers found a bacterium that can live without phosphorus — something scientists didn't think life forms, at least those we know about, can do.

What's more, it's able to survive on a diet heavy in arsenic, which we all know isn't good for you.

Among the feverish headlines is FoxNews.com's "Are Aliens Among Us? Sort Of, NASA Says."

We've turned to NPR's Science Desk for an explainer. Here's what Jon Hamilton has filed for the next newcast:

"One of the truisms of science is that life isn't possible without six elements, one of which is phosphorus.

"But a young scientist at NASA wondered whether that truism was really true. She thought arsenic, which is chemically very similar to phosphorous, might work as a substitute.

"So she and other researchers began studying tiny organisms taken from the mud of Mono Lake in California. That mud contains a lot of arsenic. And they found at least one bacterium that was able to adapt to a diet that included lots of arsenic, but no phosphorus.

"What's more, the bacterium appeared to be using arsenic instead of phosphorus in its DNA. Scientists say that suggests organisms could exist in places on earth, or elsewhere in the universe, that were previously thought incapable of sustaining life."

NASA sums up news this way: "This finding of an alternative biochemistry makeup will alter biology textbooks and expand the scope of the search for life beyond Earth. The research is published in this week's edition of Science Express."

And there's a free abstract from that Science Express paper here. An excerpt:

"Our data show evidence for arsenate in macromolecules that normally contain phosphate, most notably nucleic acids and proteins. Exchange of one of the major bioelements may have profound evolutionary and geochemical significance."

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