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Searching for life on Mars is not easy, not only is the Red Planet difficult to reach, but it is completely inhospitable to life as we know it. However, there are places on Earth that can tell us how life appeared on Mars at some point during the planet’s 4.5 billion year history.
And according to the study, which was published in the journal Frontiers in Astronomy and Space Science on January 29, scientists have discovered a few specialized microbes in conditions similar to those in the early history of Mars, in Laguna Lake. Laguna Caliente (Hot Lake), with a diameter of about 365 meters, is located in the crater of the active Poás Volcano volcano in Costa Rica, Central America.
As Science Alert reports, researchers from the University of Colorado Boulder in the US studied bacteria to learn more about how they adapt to survive in these harsh conditions. They find that it survives thanks to a wide variety of adaptations, including pathways to generate energy using sulfur, iron and arsenic.
Lake “Laguna Caliente”
It is one of the most acidic lakes in the world, and its water is blue in color, full of toxic minerals, and has a severe corrosive effect on materials, so it is not suitable for life in it, and the bottom of the lake is covered by a layer of liquid sulfur.
This lake is one of the most inhospitable habitats on earth, as the water is highly acidic and full of toxic minerals, and its crater water temperatures can reach nearly boiling point, making life difficult for any living creature living in it.
Additionally, the lake is prone to frequent “volcanic eruptions” that cause sudden eruptions of steam, ash, and rock. Although these eruptions are deadly, scientists claim that the bacteria that live in that volcanic lake hold the key to understanding how life began and survived on Mars.
Ongoing research
This multidisciplinary study follows up on previous work from 2013. At the time, a research team led by the University of Colorado Boulder found that there was only one type of bacteria in the genus Acidiphilium, or “acid lover,” and this type of bacteria is common in mine drains. acidic and hydrothermal systems, and is known to have multiple genes adapted to diverse environments.
In 2017, the Boa volcano erupted explosively, and a team of researchers decided to re-visit the lake to find out how the ongoing volcanic activity affected the microbial community they identified in 2013, and whether there were changes in microbial diversity, as well as to study the biochemical processes of the organisms more comprehensively , especially since volcanic eruptions have the ability to completely sterilize a volcanic lake.
“One of our main findings is that inside this extreme volcanic lake, we only discovered a few types of microorganisms,” says lead author of the new study, Justin Wang, a graduate student at the University of Colorado Boulder. “However, there are many potential pathways for survival.” .
“We believe they do this by staying at the edge of the lake when eruptions occur. This is when a relatively wide range of genes is beneficial,” he added in the press release published on the Eurek Alert website.
The team says the lake’s environment is similar to that found on Mars during its early history, suggesting that some simple life may have formed on Mars at a time when the planet still had running liquid water.
big surprise
This latest work shows that there is a bit more biodiversity, but that there is still a dominance of bacteria of the genus Acidophilim. By sequencing the bacteria’s DNA in the lake samples, the team confirmed that it had a variety of biochemical capabilities to help it withstand harsh and dynamic conditions.
These capabilities have included pathways for energy generation using sulfur, iron, arsenic, carbon fixation (such as plants), simple and complex sugars, and bioplastic granules (which microorganisms can leave behind and use as energy and carbon reserves during stress or starvation).
“We expected a lot of the genes we found, but we didn’t expect that many due to the low biodiversity of the lake. This was a big surprise. It stands to reason that this is how life would adapt to living in an active crater lake,” explains the study’s lead author.
Searching for signs of life
Although this environment is often fatal, hydrothermal systems provide most of the major components for the development of life, including heat, water, and energy. This is why the leading theories of both Earth and Mars focus on these locations.
So, the researchers argue, the ways in which these extreme microbes adapt to their “infernal” environment could show us how microbes might once have lived on the wetter and more volcanic planet Mars.
“Our research provides a framework for how life might exist on Earth in hydrothermal environments on Mars,” says Wang. “Whether or not life has existed on Mars before, and if it resembles the microorganisms we have here, is still a big question. We searched studies to prioritize searching for signs of life in such environments.”
By understanding how extreme bacteria survive on Earth, the team hopes that when samples of Martian rocks are brought in, it will be easier to identify chemicals that could be evidence of alien life in the past.
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