Sulfolobaceae

Sulfolobaceae is a family of thermophilic, acidophilic archaea within the order Sulfolobales, class Thermoprotei, phylum Thermoproteota (formerly Crenarchaeota). Members are predominantly found in sulfur-rich geothermal environments such as hot springs, solfataras, and volcanic vents, often at low pH.

They are aerobic or microaerophilic chemolithoautotrophs or chemoorganotrophs, deriving energy from oxidation of reduced sulfur compounds (such as elemental sulfur and sulfide) and using CO2 as a carbon source. They typically thrive at high temperatures (optimal around 70–80°C) and low pH (around pH 2–4). They have cell envelopes with an S-layer and thermophilic enzymes; some species tolerate sulfuric acid and exhibit acid-stable enzymes.

In geothermal ecosystems, Sulfolobaceae contribute to sulfur cycling and mineral weathering, often dominating microbial communities in acidic, sulfidic environments. They can form biofilms and have adaptable metabolisms that allow growth on different sulfur species or carbohydrates in some cases (if chemoorganotrophic). Genera include Sulfolobus and Metallosphaera as representative members.

Sulfolobus solfataricus and Sulfolobus islandicus are among the best studied representatives; their genomes have been fully sequenced and illuminate archaeal DNA replication, transcription, and repair in extreme conditions. Sulfolobaceae members possess CRISPR-Cas systems and thermostable enzymes of industrial interest; their study informs archaeal physiology and evolution.

Notes on taxonomy: The family is part of the expanding reorganization of crenarchaeal taxonomy; names and boundaries may vary with the taxonomy database used (GTDB, NCBI). They are not known as human pathogens.