Tuesday, June 18, 2013


A team of researchers from the Department of Natural Resource Sciences at McGill University have discovered a new bacterium living within the permafrost on Ellesmere Island in the Canadian high Arctic. The bacteria are able to thrive at –15ºC, the coldest temperature ever reported for bacterial growth. This discovery allows insight into the preconditions for microbial life on both Saturn’s moon Enceladus as well as Mars; both are thought to contain briny subzero conditions. Mars has recorded differing values for its surface temperature with a common value being −55 °C while Enceladus’ surface temperature is around -201°C.

The bacterium, Planococcus halocryophilus OR1 (electron microscope image here:http://bit.ly/10PGWGm), was discovered after the team screened about 200 separate High Arctic microbes, attempting to find the microorganism that was best adapted to the Arctic permafrost. The bacterium is believed to live within the thin veins of briny water within the permafrost on Ellesmere Island. The water, at~-16ºC, is not frozen, as the salt content is so high; this makes the environment habitable. The organism is capable of staying alive to at least -25ºC in the permafrost.

The team studied the genomic sequence and other molecular traits of P. halocryophilus OR1 and discovered the organism has significant modifications in its cell structure and function. The bacterium also contains increased amounts of cold-adapted proteins and the team observed changes to the membranes surrounding the bacterium, which allowed it some protection from the harsh environment it inhabits. P. halocryophilus OR1 is also able to maintain high levels of compounds that act like a molecular antifreeze, which keeps the bacterium from freezing as well as protecting the cell from the briny environment.

These microbes may also play a harmful role in very cold climates like the Arctic through increasing carbon dioxide emissions from the melting permafrost.

Image credit: Joel Barker, courtesy of Ohio State University.

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