noun, plural: mesophiles
An organism that lives and thrives at moderate temperatures
A mesophile is an organism that grows at moderate temperatures. It is different from a thermophile, which is capable of living at temperature as high as 80°C and above. Mesophiles grow best at moderate temperatures, i.e. 20 and 45 °C, which are not too hot and not too cold. The term mesophile generally applies to microorganisms. Bacteria, in particular, may be classified into thermophilic, mesophilic, and psychrophilic. As noted earlier, the thermophilic bacteria are active when the temperature is relatively high. Psychrophilic bacteria, in contrast, are active when the temperature is relatively low. The differing optimal temperature in these bacteria is dependent upon the bacterial expression of certain alleles resulting in the production of enzymes that function at particular temperatures. One such example is a study on mesophilic and psychrophilic bacteria. Accordingly, modification of genetic elements in mesophilic bacteria resulted in the changing of their temperature range to closely match that of the psychrophilic bacteria.1
Several human pathogens as well as human microbiome are considered mesophiles. It is because the normal body temperature of humans is 37 °C. Some mesophiles are involved in wine and beer making. They are also found in cheese and yogurt.2
Examples of mesophilic bacteria are Listeria monocytogenes, Streptococcus pyrogenes, Staphylococcus auresu, etc.
Word origin: meso- (middle) + phile (love)
1 Pankowski, J. A., Puckett, S. M., & Nano, F. E. (15 March 2016). “Temperature Sensitivity Conferred by ligA Alleles from Psychrophilic Bacteria upon Substitution in Mesophilic Bacteria and a Yeast Species”. Applied and Environmental Microbiology. 82 (6): 1924–1932.
2Mesophile. Wikipedia.org. Retrieved from ://en.wikipedia.org/wiki/Mesophile.