There is life on earth that was previously considered impossible. Image: Thomas S / pixelio.de
Read out Attention: The results of the research were disproved in 2012 The Earth has its own aliens: researchers have discovered a bacterium that can use the toxic element arsenic instead of the vital phosphorus for the production of important cell building blocks. It thereby survives the high arsenic concentrations in the salt lake Mono Lake in California. By means of modern analysis methods, the scientists were able to document the replacement of phosphorus by arsenic in many cell components, even the genetic material of the bizarre bacterium. Conclusions and consequences not only for earthly life, but also for possible life forms on other planets would result from this realization: "If a being of the earth can do something so unexpected, it throws a new light on the possibilities of life in general", says study leader Felisa Wolfe-Simon from the Astrobiological Institute of NASA in California. Until now, the basic principle of biology on our planet has been that all life forms rely on six elements: carbon, hydrogen, oxygen, nitrogen, sulfur and phosphorus. Phosphorus compounds, for example, form a basic component of DNA, the carrier substance of the genetic information of all living beings. In addition, the element is involved in many fundamental metabolism and regulatory processes in cells.

Now, however, the list of basic elements of life must obviously be rewritten: according to the new findings, it is now called "phosphorus or arsenic". Normally, arsenic is highly toxic to living things because it interferes with their metabolic processes. However, it has some chemical similarities to phosphorus, the scientists say. These characteristics apparently use the bacterium from the family of Halomonadaceae, in order to be independent of phosphorus, as the studies showed.

The researchers cultured the bacteria under laboratory conditions on a nutrient medium, replacing step by step phosphorus with arsenic. At the end of the experiment, the bacteria proved they did not need any phosphorus to survive. The following analyzes of the researchers finally confirmed the replacement of the element by arsenic in the vital components of the microorganisms: In proteins, lipids and even in DNA, the bizarre bacteria had exchanged phosphorus for arsenic.

The astrobiologist and co-author of the study Ariel Anbar, from Arizona State University in Tempe, underlines the importance of the results: "A basic principle in the exploration of possible life outside the earth was to approach the availability of the supposed six elements of life hold. The new findings show that we need to continue thinking in this regard: life can be quite different on our planet than we previously knew, "says Anbar. display

Felisa Wolfe-Simon (Astrobiology Institute of NASA, California) et al .: Science, 10.1126 / science.1197258 dapd / science.de? Martin Vieweg

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