Beneath the permafrost of Lost Hammer Spring in the Canadian High Arctic is an extremely salty, very cold, and nearly oxygen-free environment most similar to some areas on Mars. So if you want to understand more about the types of life forms that may have once existed – or may still exist – on Mars, this is a fantastic place to look. After an extensive search under extremely difficult conditions, scientists from McGill University discovered microbes that had never been identified before. In addition, they gained insight into their metabolism using state-of-the-art genomic techniques. researchers have shown for the first time that microbial communities discovered living in the Canadian High Arctic, in conditions similar to those on Mars, can survive by eating and breathing simple inorganic compounds of the type found on Mars (such as methane, sulfate, sulfide, carbon dioxide and carbon monoxide). The discovery is so compelling that the European Space Agency has selected Lost Hammer’s surface sediment samples to test the life-detection capabilities of the device that will be used on the upcoming ExoMars mission.
Developing a plan for life on Mars
Lost Hammer Spring in Nunavut in the Canadian High Arctic is one of the saltiest and coldest terrestrial springs ever discovered. The water that moves through the 600 meters (2,000 ft) of permafrost to the surface is extremely salty (~24% salinity), permanently at subzero temperatures (~-5 °C/23 °F), and contains almost no oxygen. (<1 ppm dissolved oxygen). Extremely high concentrations of salt protect the Lost Hammer spring from freezing, allowing it to maintain a liquid water environment even in sub-zero temperatures. These conditions are analogous to those found in certain regions of Mars where extensive salt deposits and possible cold salt springs have been observed. While previous research has shown the presence of microbes in this kind of Mars-like environment – this is one of the few studies that has found microbes alive and active.
To gain insight into the kind of life forms that might exist on Mars, scientists used state-of-the-art genomic tools and single-cell microbiology methods to identify and characterize the new, and more importantly, active microbial community in this unique spring. Finding microbes and then sequencing their DNA and mRNA was not an easy task. The team of scientists at McGill University was led by Lyle Whyte of the Department of Natural Resource Sciences.
Surviving in difficult conditions requires an unusual form of life
“It took several years of working with the sediment before we were able to successfully detect active microbial communities,” explains Elisse Magnuson, a PhD student in Whyte’s lab and first author of the paper. “Environmental salinity interferes with both extraction and sequencing of microbes, so when we were able to find evidence of active microbial communities, it was a very satisfying experience.”
The team isolated and sequenced DNA from the spring community, allowing them to reconstruct the genomes of around 110 microorganisms, most of which had never been seen before. These genomes allowed the team to determine how such creatures survive and thrive in this unique extreme environment, which acted as blueprints for potential life forms in similar environments. Through mRNA sequencing, the team was able to identify active genes in the genomes and essentially identify some very unusual microbes actively metabolizing in the extreme spring environment.
No organic material is needed to support life
“The microbes we found and described at Lost Hammer Spring are surprising because, unlike other microorganisms, they do not depend on organic material or oxygen for life,” adds Whyte. “Instead, they survive by eating and breathing simple inorganic compounds such as methane, sulfides, sulfate, carbon monoxide, and carbon dioxide, all of which are found on Mars. They can also fix carbon dioxide and nitrogen gases from the atmosphere, making them highly adapted to survive and thrive in very extreme environments on and off Earth.
The next steps in the research will be to cultivate and further characterize the most abundant and active members of this strange microbial ecosystem to better understand why and how they thrive in the very cold, salty mud of Lost Hammer Spring. Scientists hope that this, in turn, will help interpret the exciting but mysterious isotopes of sulfur and carbon recently recovered from NASA’s Curiosity Rover in Gale Crater on Mars.
Source Reference: Elisse Magnuson, et. al, Active lithoautotrophic and methane-oxidizing microbial community in an anoxic, sub-zero, and hypersaline High Arctic spring” by, 8 April 2022, The ISME Journal. DOI: 10.1038/s41396-022-01233-8
