Poison Nil: Mono Lake Bacterium Exhibits Exotic Arsenic-Driven Biological Activity

Life as we know it is remarkably diverse and adaptive, permitting organisms to gain a toehold in some of the most outwardly inhospitable places on the planet. But it tends to rely on a tidy, predictable array of six nutrient elements, a modest alphabet of basic biology that leaves open the possibility of other combinations making up entirely different kinds of biological activity. Life as we know it, then, might not be all there is—for either terrestrial or extraterrestrial biology.

That possibility looks more promising in the light of a new study describing a bacterium isolated from California's Mono Lake that can use arsenic, which is usually poisonous to life, as one of its key nutrient elements. The microbe can even take up arsenic into its biomolecules, replacing phosphorus as a structural building block in DNA and possibly in energy-carrying molecules such as adenosine triphosphate (ATP) as well. The study appeared online December 2 in Science.