Canadian High Arctic Bacterium Offers Clues to Life on Mars

A Canadian-led team of researchers has discovered a bacterium that grows in the Canadian high Arctic much below freezing point. The bacterium is able to grow at -15 degrees C in one the coldest temperature ever reported for bacterial growth.

The discovery of the bacterium Planococcus halocryophilus OR1 was made in Ellesmere Island, Canada.  The bacterium discovered in permafrost provides interesting clues about the crucial preconditions for microbial life on Saturn's moon Enceladus and Mars as similar briny subzero conditions are known to exist there.

The team of researchers screened nearly 200 separate high Arctic microbes in order to find the microorganism that can very well adapt to the harsh environment conditions of Arctic permafrost.  They noticed that it was a strain of Planococcus halocryophilus that managed to multiply in the tiny veins of briny solution in Arctic permafrost.

"We believe that this bacterium lives in very thin veins of very salty water found within the frozen permafrost on Ellesmere Island," Prof. Lyle Whyte from the Deptartment of Natural Resource Sciences at McGill University, said in a press statement. "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."

In order to understand how Planococcus halocryophilus is able to survive, the researchers studied its genomic sequence as well as other molecular traits. They noticed that the bacterium adapts well to extremely cold salty conditions. This is due to its cell structure, function and high level of cold adapted proteins.  This even consists of alteration to the membrane that covers the bacterium and guards it against the harsh environment.

Apart from this, while conducting the genome sequence, they also noticed that the bacterium maintains high levels of compounds within the cell that partially plays the role of a molecular antifreeze, keeping the microbe from freezing solid and simultaneously protecting it from the briny environment.  

The study researchers predict that such microbes can be dangerous in extremely cold environment such as the high Arctic as they can elevate the carbon dioxide emissions from the melting permafrost.

This study throws light on how similar microbial life may exist elsewhere in the Solar System. The study details were published in ISME Journal on Wednesday.