Few specialized microbes live in conditions similar to those found in the early history of Mars, thanks to a wide range of adaptations.
The hydrothermal crater lake of the Boa Volcano in Costa Rica is one of the most hostile habitats on the planet. The water is highly acidic and full of toxic minerals, and crater water temperatures can range from comfortable to near boiling point, making life difficult for any neighborhood. Live in the water.
In addition, the lake is full of toxic metals, is too acidic, and is prone to frequent “volcanic eruptions” that cause sudden explosions of steam, ash and rock.
Despite these deadly eruptions, scientists claim that bacteria that live in a boiling volcanic lake, which is regularly filled with toxic metals and acidic water, hold the key to understanding how life began and survived in the rugged terrain of Mars.
“One of our main findings is that inside this harsh volcanic lake, we only detected a few types of microorganisms,” says lead author of the study, Justin Wang, a graduate student at the University of Colorado Boulder in the US. “Potential ways to survive…we think they do this by staying at the edge of the lake when eruptions occur. That’s when a relatively wide range of genes is beneficial.”
Researchers from the University of Colorado Boulder studied bacteria to learn more about how they adapt to survive in these conditions.
They find that it survives thanks to a wide variety of adaptations, including pathways to generate energy using sulfur, iron and arsenic.
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 the Red Planet at a time when the planet still had running liquid water.
This multidisciplinary study follows up on previous work conducted in 2013. At the time, researchers found that there was only one type of bacteria coming from the genus Acidiphilium in the volcanic Boa Lake. Unsurprisingly, this type of bacteria is commonly found in acid mine drainage and hydrothermal systems, and is known to have multiple genes adapted to diverse environments.
In the following years, there were a series of explosions and the team returned in 2017 to see if there were changes in microbial diversity, as well as to study the biochemical processes of the organisms more thoroughly. This latest work shows that there is a bit more biodiversity, but that Acidiphilium still dominates.
By sequencing the DNA of the organisms in the lake samples, the team confirmed that the bacteria have a variety of biochemical capabilities to help them withstand extreme and dynamic conditions.
These included pathways for power generation using sulfur, iron, arsenic, carbon fixation (such as plants), simple and complex sugars and bioplastic granules (which microorganisms can create 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,” Wang explains. “This was a big surprise. It stands to reason that this is how life would adapt to living in an active crater lake.”
Although this environment is often fatal, hydrothermal systems provide most of the key 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.
It is noteworthy that the lake is located about 7,500 feet above sea level, its width is 984 feet and its depth is about 100 feet.
“Our research provides a framework for how life exists on Earth in hydrothermal environments on Mars. Whether life existed on Mars before, and whether or not it resembled the microorganisms we have here, is still a big question,” Wang said. Our research guides studies to prioritize searches for signs of life in such environments.”
By understanding how extreme bacteria survive on Earth, the team hopes that when rock samples are returned from Mars, it will be easier to identify chemicals that could be evidence of alien life in the past.
The study was published in Frontiers in Astronomy and Space Science.