Scientists finds first place on Earth where life can not be exist
Scientists finds first place on Earth where life can not be exist
We have just found the first place on Earth that is biochemically incompatible with life: A few months ago, the professor of physiology Juan Ignacio Pérez said that ” in the places of our planet where we have searched, life has been found “. From underground lagoons to hundreds of meters under the frozen Antarctic soil to the volcanoes’ fumaroles at more than 100º of temperature , this planet is simply infected with life everywhere.
“Life, one way or another, can with everything” or so we came to think. However, a Spanish-French team has just turned the matter around by finding a place that embodies the boundary conditions that terrestrial organisms can withstand: Dallol, the only place in the world that, as far as we know, is not suitable for any type of life .
Living things, especially microorganisms, have a surprising ability to adapt to the most extreme environments on our planet, but there are places where they cannot survive. European researchers have confirmed the absence of microbial life in some salty, hot and hyper-acidic ponds of the Dallol geothermal field in Ethiopia.
The infernal landscape of Dallol , located in the Ethiopian depression of Danakil, extends over a volcanic crater full of salt , where toxic gases emanate and the water boils amid intense hydrothermal activity. It is one of the most steamy environments on Earth. There the daily temperatures in winter can exceed 45 ° C and hypersaline and hyperacid ponds abound, with even negative pH values.
A recent study, published this year , pointed out that certain microorganisms can survive in this multi-extreme environment (very hot, saline and acid at the same time), a discovery that has led its authors to present this place as an example of the limits that it can support life , and even to propose it as a terrestrial analogue of primitive Mars.
However, now a Franco-Spanish team of scientists led by the purification biologist López García of the National Center for Scientific Research (CNRS) in France, has published an article in the journal Nature Ecology & Evolution where the opposite is concluded. According to these researchers, there is no life in the multi -xtrema ponds of Dallol .
“After analyzing many more samples than in previous works, with adequate controls to avoid contamination and a well calibrated methodology, we have verified that microbial life is absent in these salty, hot and hyperacid pools , as well as in adjacent brine lakes rich in magnesium ”, underlines López García.
“What there is is a great diversity of halophilic archaea (a type of primitive salt-loving microorganisms) in the desert and the salt canyons around the hydrothermal site – clarifies the biologist – but not in the hyperacid and hypersaline ponds themselves, nor in the so-called Black and Yellow lakes of Dallol where magnesium abounds. And all this, although the microbial dispersion by wind and human visitors in this area is intense. ”
Same result with different methods
This is confirmed by the results of all the methods that the team has used, which are as varied as massive sequencing of genetic markers to detect and classify microorganisms, microbial culture attempts , fluorescent flow cytometry to identify individual cells, chemical brine analysis and scanning electron microscopy combined with x-ray spectroscopy.
López García warns that some silica-rich Dallol mineral precipitates may look like microbial cells under a microscope , so you have to analyze well what you are seeing: “In other studies, apart from the possible contamination of samples with arches from adjacent lands, these mineral particles may have been interpreted as fossilized cells, when they actually form spontaneously in brines even if there is no life. ”
“In addition, our study presents evidence that there are places on the earth’s surface, such as Dallol pools, which are sterile even if they contain water, ” said López García. This means that the presence of liquid water on a planet, which is often used as a habitability criterion, does not directly imply that it has life .
Two barriers to life
In this case, researchers have found two physical-chemical barriers that prevent the presence of living organisms in ponds: the abundance of chaotropic magnesium salts (an agent that breaks the hydrogen bonds and denatures the biomolecules) and the simultaneous confluence of hypersaline, hyper-acid and high temperature conditions.
” We would not expect to find ways of life in similar environments of other planets , at least not based on a biochemistry similar to the terrestrial,” says López García, who insists on the need to have multiple clues, analyze all kinds of alternatives and be very cautious with interpretations before concluding anything in astro-biology.
Both the Franco-Spanish group, in which researchers from the Geological and Mining Institute of Spain and the Autonomous University of Madrid participate, as well as other international teams continue to investigate the extreme environment of Dallol , where completely sterile pools could alternate with others with conditions slightly better biophysics that allow the presence of archaea and other extreme microorganisms. In any case, an ** exceptional environment ** to continue studying the limits of life.
The biochemical limits of life
But when they went to study them, after carrying out the most important study to date, they found that ” microbial life is absent in these salty, hot and hyperacid pools, as well as in adjacent brine lakes rich in magnesium,” explained Purification López García of the National Center for Scientific Research (CNRS) of France.
That is, the matter became much more crucial: we were facing the only known place that was biochemically incompatible with life . That ensures that Dallol’s crater will become one of the most studied places in the world to try to find the limits of life.
Anticipating it, the researchers have contributed some hypothesis. In his opinion, the two “biochemical barriers” that prevent life are the abundance of chaotropic magnesium salts (which denatures biomolecules) and the fact that there are, at the same time, conditions of hypersalinity, hyperracidity and high temperature. We will soon know if there is anything else.
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