sulfurisphaera sulfurisphaera sulfurisphaera is a genus of the sulfolobaceae. sulfurisphaera scientific classification domain: archaea kingdom: proteoarchaeota superphylum: tack group phylum: thermoproteota class: thermoprotei order: sulfolobales family: sulfolobaceae genus: sulfurisphaerakurosawa et al. 1998 type species sulfurisphaera ohwakuensiskurosawa et al. 1998 species s. javensis s. ohwakuensis s. tokodaii description and significance sulfurisphaera is a facultatively anaerobic, thermophilic, gram-negative archaeon that occurs in acidic solfataric fields. the organism grows under the temperature range of 63–92 °c with the optimum temperature at 84 °c, and under the ph range of 1.0–5.0, with an optimum of ph 2.0. it forms colonies that are smooth, roundly convex, and slightly yellow. genome structure the genome of sulfurisphaera is yet to be sequenced. the g + c content is estimated to be 30–33%. cell structure and metabolism the spherical cells of sulfurisphaera ohwakuensis are 1.2–1.5 µm in diameter. thin sections of the organism reveal an envelope (approx. 24 nm) surrounding the cell membrane. it grows organotrophically on proteinaceous, complex substrates such as yeast extract, peptone, and tryptone. growth was not observed on single sugars or amino acids such as d-glucose, d-galactose, d-fructose, d-xylose, lactose, maltose, sucrose, alanine, glutamate, glycine, and histidine. ecology the strains of sulfurisphaera ohwakuensis were isolated from multiple locations in the acidic hot springs in ohwaku valley, hakone, japan.