hyperthermophily

Hyperthermophily refers to the property of organisms that grow best at very high temperatures, typically above 80°C. Most hyperthermophiles are Archaea, though a subset of bacteria can also inhabit extreme heat. Their optimum growth temperatures generally span about 80–110°C, with some vent-associated species enduring or thriving near 120°C. They inhabit environments such as deep-sea hydrothermal vents, volcanic hot springs, and geothermally heated soils.

Metabolism and ecology of hyperthermophiles are diverse. Many are chemolithoautotrophs or chemoorganoheterotrophs, often deriving energy from hydrogen oxidation or sulfur reduction. Carbon fixation frequently occurs via the reductive acetyl-CoA pathway or other high-temperature carbon fixation routes, enabling primary production in environments with limited organic matter. Some hyperthermophiles are capable of heterotrophic growth on organic substrates at high temperatures.

Cellular and molecular adaptations underlie life at extreme heat. Archaea in particular utilize membranes composed of ether-linked isoprenoid lipids, including tetraether lipids that can form monolayers, which enhance membrane stability under heat and pressure. Proteins exhibit enhanced ionic networks and hydrophobic core stability, along with heat-stable chaperones and enzymes. DNA stabilization often involves reverse gyrase, an enzyme that introduces positive supercoils to maintain genome integrity. Intracellular solutes such as di-myo-inositol phosphate or mannosylglycerate also contribute to macromolecular stabilization.

Notable hyperthermophiles include archaeal genera such as Pyrococcus, Thermococcus, and Sulfolobus, and bacterial representatives like Aquifex and Thermotoga. Hyperthermophiles have yielded thermostable enzymes widely used in biotechnology, including high-fidelity DNA polymerases derived from Pyrococcus species for polymerase chain reaction applications.