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Update 11 July 2012: Following a series of critiques last May, Science has now published two papers, at the University of British Columbia in Vancouver, Canada, and at ETH Zurich in Switzerland, debunking the claim that the Mono Lake bacterium can incorporate arsenic into its DNA.

Science has not withdrawn the original paper, but it has issued an which says that “the new research clearly shows that the bacterium, GFAJ-1, cannot substitute arsenic for phosphorus to survive”.

Original article, posted 27 January 2012

LIFE may not be built on a foundation of poison after all.

A year ago, , then at NASA’s in Menlo Park, California, stirred controversy with claims that, in the lab, she had encouraged bacteria from an arsenic-rich lake in California to swap the usual phosphorus in their DNA for toxic arsenic.

Now, after trying to grow the same strain of bacteria in a soup containing arsenic, . “To the limit of what our spectrometer will detect, there’s no arsenic in the DNA,” says Rosie Redfield of the University of British Columbia in Vancouver, Canada, who .

Wolfe-Simon has defended her original results and is continuing to analyse her lab-grown bacteria at the Lawrence Berkeley National Laboratory. “As far as we know, all the data in our paper still stand,” she told Â鶹´«Ã½. “We shall certainly know much more by next year.”