Two new studies published in Science seem to refute a December 2010 study published in Science by NASA researchers that suggested bacteria could live on arsenic instead of phosphorus, reports Popular Science's Rebecca Boyle. NASA researchers led by Felisa Wolfe-Simon found a bacterium called GFAJ-1 in California's Mono Lake, and fed it arsenic while depriving it of phosphorus — and the bacteria grew. But many researchers called foul when the study was published, saying it was flawed, and set out to see if the results would hold up to replication.
Tobias Erb and his colleagues at the Institute of Microbiology at ETH Zurich and Princeton's Marshall Reaves and his colleagues have published studies in Science that show that while the bacterium can grow under high-arsenate conditions, it does need a little bit of phosphorus to survive, Boyle says. Erb's team notes that there was a small amount of phosphorus in Wolfe-Simon's study, but refuted Wolfe-Simon's conclusion that this amount was too small to sustain the bacteria. Erb's team says the phosphorus was enough to keep GFAJ-1 alive. The Reaves paper — which includes the University of British Columbia researcher Rosie Redfield in its list of authors — says that no arsenic was covalently bound to the bacteria's DNA, Boyle adds.
USA Today quotes Wolfe-Simon's response: "There is nothing in the data of these new papers that contradicts our published data," she says. The newspaper also notes that her team is planning to submit more data on this topic for publication within months.
In a Retraction Watch guest post, Purdue University biologist David Sanders says Science could have avoided publishing the two new studies if it had done the right thing and never published the original study in the first place or retracted it after it was published. "The analytic techniques used to demonstrate incorporation into macromolecules such as DNA were either shoddy or didn't provide real support to the conclusions," Sanders says, adding that the supplementary tables attached to the study had important information missing and that the paper had "divergent analyses" with no explanation for the discrepancies. "For the Wolfe-Simon paper — bad data, misrepresented data, inconclusive data, contamination. Game over. No need for additional research or articles. Article was self evidently wrong and should never have been published. It should now be retracted," he adds.
At the Bad Astronomy blog, Phil Plait says the news is "disappointing," though not surprising. However, he adds, there are a few lessons that researchers can learn from this issue. Chief among them is that while the bacteria may not live exclusively on arsenic, they do thrive in arsenic-heavy waters and can adapt to extreme environments. "The ramifications for astrobiology (finding life on other planets) are still important, and this gives us strong and critical insight into the very chemistry of nature itself," he says.
Daily Scan sister publication Genome Technology spoke with Redfield about her work in March.