thermoacidophilic

Thermoacidophilic organisms, or thermoacidophiles, are microorganisms that require both high temperatures and acidic conditions for growth. They are a subset of extremophiles that typically thrive at temperatures above 60°C and at acidic pH values well below neutral. Most known thermoacidophiles belong to the Archaea, though some bacteria also display thermoacidophilic traits.

Common thermoacidophilic genera include the archaeal Sulfolobus, Metallosphaera, Acidianus, and Picrophilus, as well as acidophilic, moderately thermophilic bacteria such as Alicyclobacillus. These organisms are often found in geothermally heated environments like hot springs, volcanic vents, fumaroles, and acid mine drainage, where reduced sulfur or iron compounds are abundant.

Many thermoacidophiles are chemolithoautotrophs, deriving energy from oxidation of reduced sulfur compounds or hydrogen and fixing CO2 via autotrophic pathways. Some are capable of heterotrophy under certain conditions. Their metabolism enables them to play key roles in sulfur and iron cycles in their ecosystems.

Adaptations supporting life in hot, acidic habitats include robust, heat-stable enzymes, highly durable membranes with ether-linked lipids and sometimes tetraether lipids, and proton pumps and buffering systems that maintain cytoplasmic pH. These features also make thermoacidophiles of interest for industrial biotechnology and studies of protein stability.