A bacterium discovered in a lake high in arsenic not only metabolizes the normally toxic element, but also seems to incorporate it into its DNA and other molecules in place of phosphorus. This hints at a biochemistry very different from that long thought to underlie life on Earth.
Felisa Wolfe-Simon at the US Geological Survey in Menlo Park, California, and her colleagues found the microbe in California's Mono Lake (pictured). When cultured in arsenate with only trace amounts of phosphate, the organism grew at a rate equal to 60% of that it achieves in phosphate.
Using radiolabelling and mass spectroscopy, the team found arsenic in cellular fractions of the bacterium's proteins, lipids, metabolites and nucleic acids in amounts similar to those expected for phosphate in normal cell biochemistry. X-ray analysis suggested that the arsenic takes the form of arsenate, and bonds with carbon and oxygen similarly to phosphate.
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For details of the mixed reactions to this surprising finding see p.741.
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Microbiology: Bacteria that thrive on arsenic. Nature 468, 734 (2010). https://doi.org/10.1038/468734a
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DOI: https://doi.org/10.1038/468734a
