A species of bacteria capable of thriving at temperatures as low as -15ºC has just been discovered in the permafrost on Ellesmere Island in the Canadian high Arctic, by researchers from McGill University. The existence of the species — Planococcus halocryophilus OR1 — raises some interesting questions about the possibility of there being microbial life on other worlds in the solar system, besides the Earth.
The new bacterium is able to easily grow at temperatures as low as -15ºC, which is the coldest temperature yet reported for bacterial growth, and is nearly as cold as the surface of Mars. “The bacterium offers clues about some of the necessary preconditions for microbial life on both the Saturn moon Enceladus and Mars, where similar briny subzero conditions are thought to exist.”
The species was discovered “after screening about 200 separate High Arctic microbes looking for the microorganism best adapted to the harsh conditions of the Arctic permafrost.”
“We believe that this bacterium lives in very thin veins of very salty water found within the frozen permafrost on Ellesmere Island,” explains lead researcher Professor Lyle Whyte, from the Department of Natural Resource Sciences at McGill University. “The salt in the permafrost brine veins keeps the water from freezing at the ambient permafrost temperature (~-16ºC), creating a habitable but very harsh environment. It’s not the easiest place to survive but this organism is capable of remaining active (i.e. breathing) to at least -25ºC in permafrost.”
After discovery, the researchers investigated the species’ genomic sequence and other molecular traits, with the aim of better understanding its abilities. The researchers found that P. halocryophilus OR1 excels in the very cold, and salty, environment thanks to major modifications “in its cell structure and function and increased amounts of cold-adapted proteins. These include changes to the membranes that envelop the bacterium and protect it from the hostile environment in which it lives.”
“The genome sequence also revealed that this permafrost microbe is unusual in other ways. It appears to maintain high levels of compounds inside the bacterial cell that act as a sort of molecular antifreeze, keeping the microbe from freezing solid, while at the same time protecting the cell from the very salty exterior environment.”
Whyte concludes, “I’m kind of proud of this bug. It comes from the Canadian High Arctic and is our cold temperature champion, but what we can learn from this microbe may tell us a lot about how similar microbial life may exist elsewhere in the solar system.”
An interesting discovery, calls to mind the recent research suggesting that life on the Earth may have possibly originated in the very cold, briny environment of brinicles.