The First Microorganisms Could Use Arsenic Instead Of Oxygen

Biology

American scientists presented evidence that modern microbial mats living in sulfide waters saturated with arsenic may be associated with early life. The First Microorganisms Could Use Arsenic Instead Of OxygenDetected by scientists bacterial mats operating on the basis of arsenic in Salar de Atakama / © www.Nature.Com

The question of which element was based on the operation of early organisms, is open – and different versions are extended. Thus, photosynthesis is possible on the basis of iron, but scientists do not find evidence in the chronicles of fossils before the oxygen appearance of about 2.4 billion years ago. The use of hydrogen is also associated with certain difficulties.

Another contender for this role – arsenic. And American scientists led by a professor of marine sciences and earth sciences Peter T. Fisher in earlier studies showed the presence of photosynthesis based on arsenic in the early forms of life. However, for a more complete picture it was necessary to find modern analogues of such organisms.

It was a great difficulty, because the conditions on the young earth were very different from modern: there was no oxygen, no ozone layer, which would protect the surface from the deadly ultraviolet. But still such organisms found: they turned out to be modern arsenotrophic (that is, the microbial mats feed) are microbial mats – those inhabit, for example, in the Lakes of Salar de Atakam in the north of Chile.

There is extremely dry climates, high temperature fluctuations, strong ultraviolet radiation (due to high height, because the terrain is mountainous) and very salted water that does not contain oxygen, but in excess containing arsenic and sulfur – local volcanic products. Inhabitants in such conditions of microorganisms, according to scientists, can be called analogues of those that lived on the young earth.

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