![]() ![]() These physiological changes can be classified into two broad types of cellular response. How does this organism achieve such physiological flexibility, and what are the evolutionary advantages and implications of this capability?įluctuations in temperature induce broad physiological changes in cells, including growth rate, alterations to cell wall and membrane composition, translation, and energy metabolism (Barria et al. olearia) is an anaerobic thermophile from the bacterial phylum Thermotogae with a growth range that spans almost 60 ☌ (DiPippo et al. Kosmotoga olearia TBF 19.5.1 (hereafter referred to as K. Microorganisms with temperature ranges >50 ☌ are rare and, to date, research into the few that have ranges >40 ☌ has focused on psychrophiles (e.g., Mykytczuk et al. ![]() For example, Escherichia coli O157:H7 thrives in the laboratory between 19 and 41 ☌ (Raghubeer and Matches 1990), while Geobacillus thermoleovorans has a growth range of 37–70 ☌ (Dinsdale et al. However, individual microbial species grow only within a much narrower temperature interval. 2013), and temperature is one of the most important physical factors determining their distribution, diversity, and abundance (Schumann 2009). Microorganisms are capable of growing over an impressive temperature range, at least from −15 to 122 ☌ (Takai et al. At 77 ☌ one-third of the up-regulated genes are of hypothetical function, indicating that many features of high-temperature growth are unknown. olearia’s strategies for low-temperature growth is increased copy number of some typical cold response genes through duplication and/or lateral acquisition. Comparative genomic analysis of additional Thermotogae genomes indicates that one of K. At sub-optimal temperatures, many transcriptional changes were similar to those observed in mesophilic bacteria at physiologically low temperatures, including up-regulation of typical cold stress genes and ribosomal proteins. Notably, this transcriptional response elicits re-modeling of the cellular membrane and changes in metabolism, with increased expression of genes involved in energy and carbohydrate metabolism at high temperatures and up-regulation of amino acid metabolism at lower temperatures. The temperature treatments affected expression of 573 of 2224 K. olearia cultures grown at its optimal 65 ☌ to those at 30, 40, and 77 ☌. To identify genes correlated with this flexible phenotype, we compared transcriptomes of K. ![]() Most organisms thrive within a temperature range that rarely exceeds ~30 ☌, but the deep subsurface bacterium Kosmotoga olearia can grow over a temperature range of 59 ☌ (20–79 ☌). Temperature is one of the defining parameters of an ecological niche. ![]()
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