Metallosphaera

Metallosphaera is a genus of thermoacidophilic archaea in the family Sulfolobaceae, within the order Sulfolobales. Members of this genus are extremophiles that inhabit acidic, high‑temperature environments such as volcanic hot springs, fumaroles, and mineral-rich solfataric fields, often in geothermal regions around the world. They are typically chemolithoautotrophs, deriving energy from the oxidation of inorganic substrates such as reduced sulfur compounds or metal sulfides and fixing carbon dioxide for biosynthesis. Growth usually requires low pH and elevated temperature, with optima commonly in the 65–85 °C range and pH around 2–4.

Metallosphaera species possess the archaeal cell envelope featuring an S-layer and ether-linked lipids, a trait common to hyperthermophilic archaea. They are generally aerobic or microaerophilic, with metabolism oriented toward inorganic electron donors and acceptors; many strains can utilize elemental sulfur or sulfide as electron donors, coupling oxidation to oxygen or other acceptors. Some members are known for their capacity to oxidize metals, contributing to biomineralization and bioleaching in natural and industrial settings.

The genus includes several described species, the best known being Metallosphaera sedula, a model organism widely used in studies of extreme thermophiles and bioleaching. Genomic sequencing of Metallosphaera strains supports phylogenetic placement and understanding of their metabolic pathways. Applications of Metallosphaera research include biometallurgy, environmental microbiology, and studies of archaeal protein stability under extreme conditions.