New study disproves arsenic-loving bacteria theory

Nature : A recent paper refutes once and for all the controversial findings of a 2010 study published in Science concerning a bacterium that can supposedly survive by substituting arsenic, which is toxic, for phosphorus, which is generally considered to be indispensable. Felisa Wolfe-Simon, lead author of the original paper, had claimed that the GFAJ-1 microbe thrives in the high-arsenic conditions of Mono Lake, California, because it can metabolize the usually poisonous substance. Although that claim was challenged by many in the field, no one knew how the bacterial proteins could discriminate between molecules of phosphate and arsenate, which are nearly identical. Now Dan Tawfik (Weizmann Institute of Science, Rehovot, Israel) and colleagues, whose paper was published yesterday in Nature, have found that it all depends on a single bond between a hydrogen atom and the protein. That does not mean that arsenate does not get into the bacteria. Said Tawfik, “It just shows that this bacterium has evolved to extract phosphate under almost all circumstances.”