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Can J Microbiol. 2015 Sep;61(9):655-70. doi: 10.1139/cjm-2015-0073. Epub 2015 Jun 25.

Insights into thermoadaptation and the evolution of mesophily from the bacterial phylum Thermotogae.

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a Department of Biological Sciences, University of Alberta, 11455 Saskatchewan Drive, Edmonton, AB T6G 2E9, Canada.
b Department of Biological Sciences and Department of Computer Science, Dartmouth College, 78 College Street, Hanover, NH 03755, USA.
c Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biology, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway.


Thermophiles are extremophiles that grow optimally at temperatures >45 °C. To survive and maintain function of their biological molecules, they have a suite of characteristics not found in organisms that grow at moderate temperature (mesophiles). At the cellular level, thermophiles have mechanisms for maintaining their membranes, nucleic acids, and other cellular structures. At the protein level, each of their proteins remains stable and retains activity at temperatures that would denature their mesophilic homologs. Conversely, cellular structures and proteins from thermophiles may not function optimally at moderate temperatures. These differences between thermophiles and mesophiles presumably present a barrier for evolutionary transitioning between the 2 lifestyles. Therefore, studying closely related thermophiles and mesophiles can help us determine how such lifestyle transitions may happen. The bacterial phylum Thermotogae contains hyperthermophiles, thermophiles, mesophiles, and organisms with temperature ranges wide enough to span both thermophilic and mesophilic temperatures. Genomic, proteomic, and physiological differences noted between other bacterial thermophiles and mesophiles are evident within the Thermotogae. We argue that the Thermotogae is an ideal group of organisms for understanding of the response to fluctuating temperature and of long-term evolutionary adaptation to a different growth temperature range.


Kosmotoga; Mesotoga; lateral gene transfer; réponse au stress; stress response; thermostability; thermostabilité; transfert latéral de gènes

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