Bacteria living at subzero temperatures may increase odds of life on Mars

A newly discovered bacterial strain in Canada’s far north adds a new layer of credibility to the notion of finding microbial life on other planets or moons in our solar system, according to a Canadian research team. The team found the microbes under permafrost on Ellesmere Island, in the far reaches of the Canadian Arctic, in colder temperatures than researchers had ever thought possible. Their very existence not only sets a new record for extreme-environment microbial life on Earth, but also raises new questions about the potential for microbes to evolve in other extreme climates beyond Earth, such as Mars or the moons of Saturn and Jupiter.
Planococcus halocryophilus OR₁, as the strain is called, can stay alive and active in temperatures as low as minus 13 degrees Fahrenheit (minus 25 degrees Celsius), according to study leader Lyle Whyte, the lead study author and a Canada Research Chair of environmental microbiology at McGill University in Montreal. He co-led the study with post-doctoral researcher Nadia Mykytczuk.
The researchers procured the samples from a permafrost core that NASA had drilled on Ellesmere Island back in 2004. The space agency had been testing robotic drilling techniques for future use in missions to Mars.
The world scientific community has never seen bacteria grow in temperatures this cold. “Extremophile” microbes do exist in freezing temperatures around Earth, but up until this latest find, the record had been held by bacteria found living at 23 degrees Fahrenheit.
The Planococcus microbes live in subzero temperatures. But their domain is liquid water, which can be found even in this climate extreme only because the water has high salt content, and salt impedes ice formation. Unique adaptations to the microbe’s cell structure and functions, as well as an abundance of cold-resistant proteins, enable it to tolerate the salt and to thrive in temperatures that would kill most other microscopic life.
These microbes may become an aggravating factor for—ironically—global warming. Permafrost throughout the Arctic is melting as the climate warms, and as the frost disappears, dead organic matter that it had been containing is exposed. The bacteria eat this matter and, in the process, release additional carbon dioxide into the atmosphere. Microbes are small, but the more of them that there turns out to be, the more greenhouse gases the atmosphere will receive.
But on the bright side, they might be a net positive for future exploration of the solar system. As Whyte said in a statement, “what we can learn from this microbe may tell us a lot about how similar microbial life may exist elsewhere in the solar system.”


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