It was discovered a bacterium "alien" that feeds on arsenic. Not in the sense that alien from outer space, but its metabolism is not based on oxygen, hydrogen, nitrogen, phosphorus, sulfur and carbon as all other living beings on this planet, but on something that is poisonous to life in his complex. The bacterium is the strain GFAJ-1 family Halomonadaceae class Gamma Proteobacteria that live at the bottom of Mono Lake, a lake in California on the border of Yosemite Park, known for its extremely alkaline water (pH 10) containing high amounts of arsenic and salts that are deposited to form beautiful travertine concretions and locally are called tuffs, although geologically are not.
The bacterium has been modified in a laboratory of the Institute of astrobiology at Arizona State University ordered by Felisa Wolfe-Simon, thanks to research funded by NASA and published Thursday in Science. Now the life of the bacterium is completely up to a poison such as arsenic. The existence of such an organism is the proof that life can exist in forms very different from those we know, a figure which can not fail to take into account all space programs involved in the search for living beings on other planets. "The great news is that arsenic is utililzzato as a building block for an organization," said Professor Ariel Anbar, co-author of the study. Researchers have grown in laboratory bacteria found in the mud of Mono Lake with high levels of arsenic. A little 'time, biologists have increased the amount of arsenic in the culture medium for bacteria, microorganisms make up completely dependent on that element. That bacteria have managed to survive was a surprise to the researchers. The bacteria strain GFAJ-1 are now the only form of life known so far in which a toxic substance such as arsenic replaces the phosphate, which is essential to the vital functions of all known life forms. Phosphate is in fact the basic molecules of all cells.
Source: www.corriere.it / scienze_e_tecnologie
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