Bacteria that lives in a boiling volcanic lake, that is regularly filled with toxic metals and acidic water, hold the key to understanding how life got started, and how it survived in the inhospitable terrains of Mars, scientists claim.
A few specialist microbes, known as extremophiles, have been found living in the Poás volcano in Costa Rica, one of the most hostile habitats on the planet.
Researchers from the University of Colorado Boulder, have been studying the bacteria, to learn more about how they adapt to survive in these conditions.
These extremophiles survive thanks to a broad range of adaptations, including pathways to create energy using sulfur, iron and arsenic.
The team say the lake environment resembles those found on Mars during its early history, suggesting some simple life may have formed on the Red Planet.
Fieldwork at Lagune Caliente lake in Poás volcanic lake, Costa Rica was carried out by researcher Justin Wang (pictured) and colleagues
Water in the the Poás volcano’s crater spans from comfortable temperatures, up to near boiling point, making life hard for anything living in the water.
To add to the difficulties of survival, the lake is full of toxic metals, is ten million times too acidic to drink and is also prone to sudden explosions of steam, ash and rock.
The conditions in the lake are thought to be similar to the hot springs that once dotted a young Earth, and played host to the evolution of the first simple lifeforms.
These same hot springs are thought to have also been found across Mars, at a time when the planet still had running liquid water.
The crater and its extremely harsh lake, Laguna Caliente, dominated by a single genus of extremophile Acidiphilium bacteria, adapted in multiple ways to survive
WHAT ARE EXTREMOPHILES?
Extremophiles are organisms that live in “extreme environments,” under high pressure and temperature.
Bacteria often form on the rocks near hydrothermal vents, and have to adapt to the conditions in order to survive.
The unique enzymes used by these organisms, called “extremozymes,” enable them to function in such forbidding environments.
It’s important to note that these organisms are ‘extreme’ only from a human perspective.
While oxygen, for example, is a necessity for life as we know it, some organisms flourish in environments with no oxygen at all.
Extremophiles on Earth help scientists predict conditions bacteria could exist in on alien worlds and moons.
Justin Wang, a graduate student at the University of Colorado Boulder, said they only found a few types of organisms within the lake, but there was a multitude of ways for them to survive the harsh, toxic conditions.
‘We believe they do this by surviving on the fringes of the lake when eruptions are occurring. This is when having a relatively wide array of genes would be useful.’
Specialist microbes called ‘extremophiles’ have a remarkable array of adaptations that enable them to thrive in such surroundings.
The lake is about 7,500 feet above sea level, 984ft wide and about 100ft deep.
An earlier study by the University of Colorado Boulder team suggested it was home to a single species of bacteria named Acidiphilium, that are sometimes seen in drainage from coal mines.
This new research found more species within the hot spring, suggesting life may have been more plentiful on a young Earth and Mars than first thought.
The search for life on Mars has so far focused on stream beds or river deltas, such as the Jezero crater where the NASA Perseverance rover is currently trundling along.
The rover arrived on the Red Planet in February 2021, landing in an area just north of the Martian equator, in an area once full of running water.
While on the planet it is taking samples of rock, and looking for evidence of past bacterial life, hoping to prove microbial life once existed on the Red Planet.
The extremely harsh Laguna Caliente lake in the crater of the Poás volcano, Costa Rica may resemble some hot springs on a young Mars
More attention should be paid to the sites of past hot springs – which were present on Mars for billions of years, say the researches.
‘Our research provides a framework for how ‘Earth life’ could have existed in hydrothermal environments on Mars,’ Mr Wang explained.
‘But whether life ever existed on Mars and whether or not it resembles the microorganisms we have here is still a big question. We hope our research steers the conversation to prioritize searching for signs of life in these environments.’
Mr Wang said: ‘For example there are some good targets on the crater rim of Jezero Crater, which is where the Perseverance rover is right now.’
By understanding how the extremophile bacteria on Earth survives, the team hope that when samples of rock are returned form Mars, it will be easier to identify chemicals that could be evidence of past alien life.
More attention should be paid to the sites of past hot springs – which were present on Mars for billions of years, say the researches
Mapping the DNA of samples from the lake identified a wide array of biochemical capabilities to help them tolerate extreme and dynamic conditions.
These included pathways to create energy using sulfur, iron, arsenic and carbonlike during stress or starvation.
Mr Wang said: ‘We expected a lot of the genes that we found, but we didn’t expect this many given the lake’s low biodiversity.
‘This was quite a surprise, but it is absolutely elegant. It makes sense that this is how life would adapt to living in an active volcanic crater lake.’
Despite regular lethal surroundings hydrothermal systems provide most of the key ingredients for the evolution of life – including heat, water and energy.
This is why leading theories for the evolution of bacterial life on both Earth and Mars focus on these locations.
The study was published in the journal Frontiers in Astronomy and Space Science.
NASA MARS 2020: PERSEVERANCE ROVER AND INGENUITY HELICOPTER ARE SEARCHING FOR LIFE ON THE RED PLANET
NASA’s Mars 2020 mission was launched to search for signs of ancient life on the Red Planet in a bid to help scientists better understand how life evolved on Earth in the earliest years of the evolution of the solar system.
Named Perseverance, the main car-sized rover is exploring an ancient river delta within the Jezero Crater, which was once filled with a 1,600ft deep lake.
It is believed that the region hosted microbial life some 3.5 to 3.9 billion years ago and the rover will examine soil samples to hunt for evidence of the life.
Nasa’s Mars 2020 rover (artist’s impression) is searching for signs of ancient life on Mars in a bid to help scientists better understand how life evolved on our own planet
The $2.5 billion (£1.95 billion) Mars 2020 spaceship launched on July 30 with the rover and helicopter inside – and landed successfully on February 18, 2021.
Perseverance landed inside the crater and will slowly collect samples that will eventually be returned to Earth for further analysis.
A second mission will fly to the planet and return the samples, perhaps by the later 2020s in partnership with the European Space Agency.
This concept art shows the Mars 2020 rover landing on the red planet via NASA’s ‘sky-crane’ system