A permafrost microbe has been discovered growing at –15°C, the coldest temperature ever reported for bacterial growth.
Researchers said they found the living strain of bacteria growing in the extreme cold of the permafrost, which may offer insight into possibilities of life existing beyond Earth.
The bacterium, Planococcus halocryophilus OR1, not only survives, but thrives in the permanently frozen sub-soil. Finding the microbe in the briny conditions of the Arctic could provide some hints about what it would take for microbial life to survive in conditions found on the Saturn moon, Enceladus, or Mars, where similar frigid conditions are thought to exist.
The researchers examined about 200 separate types of microbes from the high Arctic before they found the microorganism that was 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,” said McGill professor Lyle Whyte who co-led the research team. “The salt in the permafrost brine veins keeps the water from freezing at the ambient permafrost temperature creating a habitable but very harsh environment. It’s not the easiest place to survive but this organism is capable of remaining active to at least -25ºC in permafrost.”
To make their discovery, the research team studied the genomic sequence and other molecular characteristics of the P. halocryophilus OR1 microbe. The researchers found the bacterium adapts quite well to its bitter cold and salty environment, thanks to significant adjustments in its cell structure and function, as well as having increased amounts of cold-adapted proteins. Some of these cellular modifications also include changes to the membranes that envelop the microbe and protect it from its hostile environment.
After studying the microbe’s genome sequence, the scientists also discovered the bacterium is unusual in other ways; it seems to have the ability to maintain high levels of compounds within the bacterial cell that act like molecular antifreeze, keeping the microorganism from not only from freezing solid but protects it from the salty environment.
“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,” said research co-leader Nadia Mykytczuk.
The researchers agree concerned with one possibly troubling aspect of the microbe. They think the living microorganisms can harm the bitter cold environment of areas such as the high Arctic by increasing the amount of carbon dioxide emissions from the permafrost which is now melting due to what many scientists believe is global warming.