This archaeon was isolated from one of the hot springs in Beppu-Onsen of Oita Prefecture. It is capable of decomposing hydrogen sulfide by itself and grows well under acidic conditions. It belongs to Crenarchaeota as in the case of Aeropyrum pernix K1^T(= NBRC 100138^T), but its genome (2.69 Mb) is about 1 Mb larger than that of A. pernix K1^T. The larger genome size is most probably due to the integration of a plasmid during the course of evolution, since as many as 81 genes/ORFs assigned on the genome of this archaeon show similarity to those encoded in a plasmid present in another species of Sulfolobus. In addition, the archaeon seems to contain duplications of many genes/ORFs.

Unlike the two other archaea previously analyzed at NITE-DOB, i.e. P. horikoshii OT3^T(= NBRC 100139^T) and Aeropyrum pernix, the genome of this archaeon does not seem to contain genes encoding proteins with inteins. Furthermore, it contains as many as 14 genes/ORFs that show similarity to eukaryotic genes including those encoding a eukaryotic type of selenium-binding protein, a serine/threonine protein phosphatase subunit, etc. Since these genes/ORFs could not be detected in the genomes of other archaea, S. tokodaii strain 7^T is likely to be more closely related to eukaryotes than other archaea so far analyzed.