A bacterium that lives in an arsenic-rich and salt lake at California has surprised scientists with their ability to substitute in its essential elements, including DNA and cell membranes, usual phosphorus by arsenic.
Until now, the idea has been that life on Earth must be composed of at least the six elements carbon, hydrogen, oxygen, nitrogen, sulphur and phosphorus – no example had ever been found that violates this golden rule of biochemistry.
The bacteria have been found in inhospitable environments and can consume what other life finds poisonous; this bacterial strain has actually taken arsenic on board in its cellular machinery.
The astrobiology experts at NASA say that this opens a new possible avenue to search for extraterrestrial life in the form of organisms that can live in arsenic, so far considered extremely poisonous conditions.
These special microorganisms are added to the list of so-called extremophiles, able to adapt to life in hostile conditions, with high temperature, acidity, and salinity. The Science journal says that the discovery “brings to light the first time, a microorganism that is able to use a toxic chemical element, instead of a phosphate, to live and grow.”
