Microbes living in a toxic volcanic lake could hold clues to life on Mars

May 2, 2018 by Brian Hynek, University of Colorado at Boulder
Sarah Black, who recently completed her Ph.D. in Geological Sciences at CU Boulder, collects water samples from Laguna Caliente. Credit: Brian Hynek

Researchers at the University of Colorado Boulder have discovered microbes living in a toxic volcanic lake that may rank as one of the harshest environments on Earth. Their findings, published recently online, could guide scientists looking for signs of ancient life on Mars.

The team, led by CU Boulder Associate Professor Brian Hynek, braved second-degree burns, sulfuric acid fumes and the threat of eruptions to collect samples of water from the aptly-named Laguna Caliente. Nestled in Costa Rica's Poás Volcano, this body of water is 10 million times more acidic than tap water and can reach near boiling temperatures. It also resembles the ancient hot springs that dotted the surface of early Mars, Hynek said.

The Costa Rican lake can support —but only barely. Hynek and his colleagues found microbes belonging to just a single species of bacteria in the lake water, a rock-bottom level of diversity.

"Even in an extremely harsh environment, there can still be life," said Hynek of the Laboratory for Atmospheric and Space Physics and the Department of Geological Sciences. "But then there's very little life. Mars was just as extreme in its early history, so we should probably not expect to find evidence of large-scale biodiversity there."

Laguna Caliente is chaotic, with water temperatures that can swing wildly in the span of hours and magma channels running under the lake that kick off frequent, geyser-like eruptions.

"We're at the limits of what life on Earth can tolerate," Hynek said. "It's not somewhere you want to spend a lot of time because you'd probably get covered in boiling mud and sulfur from the eruptions."

To search for living organisms in this "fringe" environment, the researchers scanned samples of lake water for DNA. In research published this month in Astrobiology, they found the signature of one species of bacteria belonging to the genus Acidiphilium—a group of microbes that scientists have previously seen in toxic drainage from coal mines and other harsh locations.

"It's not uncommon to find an environment with no life, say in a volcano that's self-sterilizing," Hynek said. "But to find a single type of organism and not a whole community of organisms is very, very rare in nature."

If life did evolve on Mars, Hynek said, it would likely have survived in ways similar to the 's bacterium—by processing the energy from iron- or sulfur-bearing minerals. Hynek has spent much of his career searching for places on Earth today that look like Mars did nearly four billion years ago, when liquid water was plentiful on the surface.

It's a hard task: Rampant volcanism during that period created volatile and mineral-rich pools of , giving rise to "Yellowstones all over Mars," Hynek said.

In 2020, NASA is planning to send the Mars 2020 Rover to the Red Planet to hunt for fossil evidence of life. Hynek said that they should look first at these "Yellowstones."

Explore further: Salt flat indicates some of the last vestiges of Martian surface water

More information: Brian M. Hynek et al, Lack of Microbial Diversity in an Extreme Mars Analog Setting: Poás Volcano, Costa Rica, Astrobiology (2018). DOI: 10.1089/ast.2017.1719

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1 / 5 (6) May 02, 2018
The search for life outside of planet earth continues unabated.

Notably because the great big mystery of how life arrived on earth remains completely baffling to all and sunder - at least to those who do not believe in an Almighty Creator who created all things - including life on earth.

Hence, it is necessary to show that life could have arisen all by itself elsewhere in the solar system if not universe. If only that can be achieved then there will be complete vindication for the disgust shown at the faintest suggestion of a supernatural creator who was able to create the whole universe.
Mark Thomas
5 / 5 (2) May 02, 2018
FredJose, if your Almighty Creator did not waste any space on Earth, as demonstrated by the article above, why would you presume the rest of the universe is wasted space?
not rated yet May 02, 2018
What I fail to grasp by the ridiculous assumptions that four billion year old fossils on Mars can be presumed from Present Era extremophiles within the Earth's mesosphere.

& FJ I am not disgusted by your monkey-instincts driven necessity for believing in the stupornatural. That bungled programming is a burden we all must struggle to overcome.

I am disgusted that drunkenly incompetent deities screwed up the universe so badly with Stupid Design!

How believable can be unproven conclusions before any evidence is collected from Mars?
Mark Thomas
5 / 5 (2) May 02, 2018
What I fail to grasp by the ridiculous assumptions that four billion year old fossils on Mars can be presumed from Present Era extremophiles within the Earth's mesosphere.

No scientist is presuming this. There is an inference it might be possible and worth a look to find out for sure. If Mars had conditions that some Present Era extremophiles could tolerate, that means it is biologically possible. If the entire solar system were swept with bacteria from outside the solar system (panspermia), then there is a good chance bacteria colonized Mars the same way it did Earth. If life had a genesis here because conditions were right, then perhaps life had a second genesis on Mars because conditions were right there too, although such conditions on Mars were more localized and shorter-lived.

In truth, we have a lot of good ideas and models, but we won't really understand whether life existed on Mars without more exploration.
not rated yet May 02, 2018
MT, I actually found myself nodding my head in approval at your rebuttal to my opinions.

Then you brought up Panspermia... Arrghh!
What I see, as the best reason to dispell the magical thinking of Pannedsquirming is the timing of the event.

Just a few billion years after the BB gun went off. During a period fraught with heavy dosage of radiation as the MW Galaxy assembled and expanded. A prototype lifeform of unknown origins flew by the barely conceived Earth to be captured.

Then, the prototype disorganized into it's respective parts for an aeon or two before reorganizing as our distant microbial ancestor. To trudge forth into a glorious future of algae & sponges & scorpions & lizards big & little.

During all the intervening billions of years there was only the singular Panspermia event. Cause where are they? All the non-ancestral space-faring protolife? No evolution? No variations? No mutations? Are not these occurrences among the veriest definitions of life?
Mark Thomas
not rated yet May 03, 2018
rrwillsj, we don't have enough evidence to prove panspermia is right or wrong, but at this point we cannot dismiss the possibility. The fact the life appears to have arisen on Earth almost immediately after it sufficiently cooled from its formation tends to support panspermia. The fact that some bacteria are extremely resistant to radiation, which is common in space, but not on Earth, also suggests life may have traveled through space.

Is it more likely that life arose on its own almost immediately on Earth, or that somewhere in the vast Milky Way galaxy for the preceding billions of years, life arose and managed to travel to Earth, possibly inside rocks and comets?

Again, we have a lot of good ideas and models, but we won't really understand whether life existed on Mars without more exploration.
not rated yet May 03, 2018
MT, the early Earth was naturally radioactive. One of the reasons for the Hadean Eon. Organisms as advanced as bacteria were to evolve much later during the Archaea.

Even in today's relatively benign Earth environment, there are limitations. Places, such as the High Antarctic Desert, were no life has been able to establish a foothold.

I opinionate that we may discover ancient, primitive fossils buried deep within Mars. But I doubt we will ever find any lifesigns there for the last couple of billion years.

Let's track the Panspermia ideal. It took billions of years for micro-organisms to establish a measurable presence on Earth.

So the PS contribution occurred before then. The originating environment (unknown) had to have been billions of years older. Somehow escaping it's native habitat and scattering among the stars?

Eventually to colonize Earth at exactly the right time to take advantage?

And then no more PS drifters happened by? Fantastical coincidence!
Mark Thomas
not rated yet May 03, 2018
MT, the early Earth was naturally radioactive.

I am talking thousands of times more radioactive, like in space.


And then no more PS drifters happened by? Fantastical coincidence!

You can't just assume that is true! What if the galaxy is awash with bacteria? On a separate thread, based on their hyperbolic trajectories, there could be 8 interstellar comets moving through our solar system right now.


This is one reason why I keep banging on table and arguing we need more actual exploration if we are going to have any hope for figuring out life here on Earth and beyond.
not rated yet May 03, 2018
Shotgun it. Hundreds of small drones & robots scattered across the Solar System would collect a lot more data than a few manned ships could ever hope for.

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