Microbiology

Bacterial Growth at −15°C

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Science  01 Mar 2013:
Vol. 339, Issue 6123, pp. 1012-1013
DOI: 10.1126/science.339.6123.1012-e

Life as a bacterium in the permafrost is not easy. Not only are subzero temperatures the norm, but the liquid water that is available is quite salty. Therefore, for bacteria to survive in these conditions, they need to be well adapted to cold and high-salinity environments. Isolated from Arctic permafrost, the aerobic heterotroph Planococcus halocryophilus is an example of one such species that is up to the task. Through a series of batch and microcosm growth experiments, Mykytczuk et al. show that P. halocryophilus grew—albeit at the slow generation time of 50 days—and had an active carbon metabolism at −15°C. Genomic analyses suggest that this organism has a diverse set of traits to help it survive in addition to those related to cold and osmotic adaptation, including several modifications to the cell envelope and increased tolerance to oxidative stress. Indeed, transcriptomic profiles from cells grown at a range of temperatures and salinities down to −15°C and 18% NaCl show specific parallel responses to mitigate cold and salty conditions. Because a large portion of the world's soil is in permafrost regions, increased activity of these microbial communities may result from warmer temperatures or greater temperature fluctuations.

CREDIT: N. C. S. MYKYTCZUK ET AL., THE ISME JOURNAL (7 FEBRUARY 2013) © NATURE PUBLISHING GROUP

ISME J. 10.1038/ismej.2013.8 (2013).

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