thermophile

Thermophiles are microorganisms that grow optimally at high temperatures. Most thermophiles have optimum growth temperatures between 45°C and 80°C; hyperthermophiles prefer temperatures above 80°C. They occur in natural high-temperature environments such as hot springs, geothermal soils, compost heaps, and deep-sea hydrothermal vents. Thermophiles include bacteria and archaea, and some eukaryotic microorganisms; however, most well-studied thermophiles are archaea and bacteria. Their proteins and membranes are adapted to heat; adaptations include heat-stable enzymes, increased ionic interactions, and saturated nonpolar lipids that help maintain membrane integrity. DNA stability is aided by higher GC content and specialized DNA-binding proteins and chaperones.

Metabolism among thermophiles is diverse. Many are chemotrophs, using inorganic or organic substrates for energy, and many are anaerobes, though others are aerobic. A subset are photosynthetic thermophiles, such as certain cyanobacteria, but photosynthesis is less common at very high temperatures.

Thermophiles have significant scientific and industrial importance. Thermostable enzymes from thermophiles, such as Taq polymerase from Thermus aquaticus, enable high-temperature molecular biology techniques like polymerase chain reaction. Other enzymes like amylases, proteases, and lipases are used in industrial processes that operate at elevated temperatures.

Notable examples include Thermus aquaticus and Thermus thermophilus; hyperthermophiles include Pyrococcus furiosus and Sulfolobus solfataricus. Studying thermophiles provides insights into the limits of life and the evolution of biomolecules under heat.