Pollo Stephen M J, Zhaxybayeva Olga, Nesbø Camilla L
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.
Can J Microbiol. 2015 Sep;61(9):655-70. doi: 10.1139/cjm-2015-0073. Epub 2015 Jun 25.
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.
嗜热菌是一类极端嗜热微生物，在温度高于45°C时生长最佳。为了生存并维持其生物分子的功能，它们具有一系列在中温生长的生物体（嗜温菌）中未发现的特征。在细胞水平上，嗜热菌具有维持其细胞膜、核酸和其他细胞结构的机制。在蛋白质水平上，它们的每种蛋白质在会使其嗜温同源物变性的温度下仍保持稳定并保留活性。相反，嗜热菌的细胞结构和蛋白质在中温下可能无法最佳发挥功能。嗜热菌和嗜温菌之间的这些差异可能为这两种生活方式之间的进化转变带来障碍。因此，研究亲缘关系密切的嗜热菌和嗜温菌有助于我们确定这种生活方式的转变是如何发生的。栖热袍菌门包含超嗜热菌、嗜热菌、嗜温菌以及温度范围足以涵盖嗜热和嗜温温度的生物体。在其他细菌嗜热菌和嗜温菌之间观察到的基因组、蛋白质组和生理差异在栖热袍菌门中也很明显。我们认为，栖热袍菌门是一类理想的生物体，有助于理解对温度波动的响应以及对不同生长温度范围的长期进化适应。
