Extremophile life

Note that many reviews and new studies have overturned (countered) the finding discussed in this article. The information presented on this page is no longer believed to be current and true.

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Canadian Press - Scientists released the results of their surprising discovery in early December 2010 on a life form once thought to be impossible. Scientists unveiled the discovery of a bacterium in the journal SCIENCE in 2011 (see source below) that can feed on arsenic, material hitherto linked to death. This extraordinary discovery broadens the possibilities of discovering life forms elsewhere in the universe, whether in our own solar system or on exo-planets.

Skeptics of extraterrestrial life will say that this form was found on Earth and in no way corresponds to a discovery on another celestial body. However, this remarkable discovery proves the adaptation of bacteria and their capacity to take forms that were previously thought impossible.

Researcher Paul Davis, an English-born physicist and professor at the University of Arizona, says: “This organism has a dual capacity. It can grow with phosphorus or arsenic. This makes him very special, even if it doesn't really make him an "alien" life form in his study published in early December 2010 in the online edition of the scientific journal Science.

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Until now, scientists considered that 6 elements were essential to carry life: nitrogen, hydrogen, sulfur, phosphorus, carbon and oxygen. But bacteria discovered at Mono Lake in California (see image) have just determined that it is possible to continue to evolve and grow by replacing phosphorus with arsenic. This disturbing discovery greatly increases the chances of finding life on other planets, even in the bacterial state. It is even believed that the same process of substitution could take place between carbon and silicon.

This discovery about the possibility of finding life in a still unknown form is important because it is imperative that scientists can recognize life when they find it. If some new paradigms show that life can adapt in forms unimaginable in the past, the possibility of finding extra-terrestrial life is therefore increased.

The discovery of this bacterium having replaced phosphorus with arsenic "demonstrates that in other planetary environments, organisms may be able to use other elements to fuel their biochemistry and that the 'normal' elements that we consider essential to life may not be essential elsewhere, ”commented British researcher Charles Cockell, professor emeritus of geo-microbiology.

It was Felisa Wolfe-Simon, study director at the NASA Institute for Astrobiology, who targeted Mono Lake because of its high arsenic levels. Arsenic and phosphorus have a similar chemical makeup, and she believed that microbes exposed to both might be able to substitute for one for the other. However, it must be repeated once again that shortly after publicly affirming this news, numerous reviews and new studies have come to invalidate this information.

It has always been believed that arsenic, an element possessing chemical behavior very similar to that of phosphorus, was toxic to life. Under these circumstances, it is a monumental discovery to have shown that phosphorus could be replaced by arsenic in certain living beings, terrestrial or extraterrestrial.

The research basically consisted of collecting samples of the bacteria GFAJ-1 and exposing it to increasing concentrations of arsenic, to which it was able to adapt to keep growing further. Research has shown that phosphorus remains the ideal support element for the growth of the bacteria, but it is with amazement that the researchers found that the bacteria adapted to arsenic. This discovery paves the way for research into extraterrestrial life in arsenic-rich environments, whether on Earth or on another planet.

According to research and studies looking at the formation of planet Earth, it is believed that arsenic was much more present at the very beginning and it is in this environment that primitive life forms could have become accustomed to the presence of this element.

This discovery revives the debate on the basic elements that can create and regulate life. But with criticism of the authors of this study and new findings in the field, it now seems unlikely that arsenic can actually replace phosphorus.

Source of the article :

https://en.wikipedia.org/wiki/Felisa_Wolfe-Simon

https://science.sciencemag.org/content/332/6034/1163

https://www.nature.com/news/arsenic-life-bacterium-prefers-phosphorus-after-all-1.11520

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