These bacteria do not eat arsenic
Among the top science stories of 2010 was a report of bacteria which eat arsenic. Following the usual process of checking new science, it seems now that the claim should have been less dramatic: the bacteria tolerate arsenic but do not metabolize it. WSJ reports:
The saga began when scientists led by Felisa Wolfe-Simon of NASA’s Astrobiology Institute published a paper that said the bacteria, found at Mono Lake in eastern California, could grow by substituting arsenic for phosphorus. The researchers had looked at Mono Lake because of its high arsenic levels, and they reported their conclusions from lab experiments.
But not everybody bought the conclusions of the paper. Last year, Science published a bunch of challenges from other scientists, and the paper has long been an object of skepticism.
For both new papers, scientists did their own tests of the bacteria. One team, led by Rosemary Redfield of the University of British Columbia in Vancouver, Canada, reports that arsenic does not contribute to the bacteria’s growth. Maybe the original results came from some sort of undetected contaminant in the arsenic the researchers used, they suggest.
The other paper, from Swiss researchers, finds the bacteria to be highly resistant to the poisonous effects of arsenic but still dependent on phosphorus to grow. They concluded that in the original experiment, trace contamination with phosphorous may have let the bacteria grow.
As the Science statement summarizes the results, the new work shows the bacterial species “does not break the long-held rules of life, contrary to how Wolfe-Simon had interpreted her group’s data.”