Microbes from surface sediment near Lost Hammer Spring, Canada, about 900 km south of the North Pole, could provide a blueprint for the kind of lifeforms that once existed, or may still exist, on Mars.
The extremely salty, very cold and nearly oxygen-free environment under the permafrost of Lost Hammer Spring in Canada’s High Arctic is most like certain areas on Mars. So if you want to learn more about the types of life forms that could once have existed — or still exist — on Mars, this is a good place to look. After much searching under extremely difficult conditions, researchers at McGill University have found microbes that have never been identified before. In addition, by using state-of-the-art genomic techniques, they have gained insight into their metabolism. In a recent article in ISME, the scientists show for the first time that microbial communities living in Canada’s high Arctic can survive in conditions analogous to those on Mars by eating and breathing simple inorganic compounds of the kind detected on Mars ( such as methane, sulfide, sulfate, carbon monoxide, and carbon dioxide). This discovery is so compelling that samples of the Lost Hammer surface sediments were selected by the European Space Agency to test the life-detection capabilities of the instruments they plan to use on the next ExoMars mission.
Developing a blueprint for life on Mars
Lost Hammer Spring, in Nunavut in Canada’s High Arctic, is one of the coldest and saltiest terrestrial springs discovered to date. The water flowing to the surface through 600 meters of permafrost is extremely saline (~24% salinity), permanent at temperatures below freezing (~ — 5°C) and contains almost no oxygen (<1ppm dissolved oxygen). The very high salt concentrations keep the Lost Hammer well from freezing, preserving a liquid water habitat even at sub-zero temperatures. These conditions are analogous to those in certain areas on Mars, where widespread salt deposits and possible cold salt springs have been observed. And while previous studies have found evidence of microbes in these kinds of Mars-like environments, this is one of the few studies in which microbes have been found alive and active.
To gain insight into the kinds of life forms that might exist on Mars, a research team from McGill University, led by Lyle Whyte of the Department of Natural Resource Sciences, used advanced genomic tools and single-cell microbiological methods to identify and characterize a novel , and more importantly, an active microbial community in this unique spring. Finding the microbes and then sequencing their DNA and mRNA was no easy task.
It takes an unusual life form to survive in difficult circumstances
“It took a few 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 the paper’s lead author. “The saltiness of the environment interferes with both the extraction and sequencing of the 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, which allowed them to reconstruct genomes of about 110 microorganisms, most of which have never been seen before. These genomes allowed the team to determine how such creatures survive and thrive in this uniquely extreme environment, acting 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 that actively metabolize in the extreme spring environment.
No need for organic matter to sustain life
“The microbes we found and described at Lost Hammer Spring are surprising because, unlike other microorganisms, they do not depend on organic matter or oxygen to live,” added Whyte. “Instead, they survive by eating and breathing simple inorganic compounds like 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, all of which makes them highly adaptable.” to both survive and thrive in very extreme environments on Earth and beyond.”
The next steps in the research are to breed 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 the Lost Hammer Spring. The researchers hope this, in turn, will help interpret the exciting yet puzzling sulfur and carbon isotopes obtained very recently from the NASA Curiosity Rover in Mars’ Gale Crater.
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