Sulfolobus acidocaldarius

Sulfolobus acidocaldarius is a thermoacidophilic archaeon that belongs to the phylum Thermoproteota. S. acidocaldarius was the first Sulfolobus species to be described, in 1972 by Thomas D. Brock and collaborators. This species was found to grow optimally between 75 and 80 °C, with pH optimum in the range of 2-3. Sulfolobus acidocaldarius was first isolated from thermal soils and hot springs with low pH in the United States of America (specifically in the Yellowstone National Park), in El Salvador, Dominica and Italy. The springs where this species was isolated had a pH less than 3 and temperatures in the range of 65-90 °C. Sulfolobus acidocaldarius is, as all Archaea, unicellular. Cells belonging to this species are spherical, albeit irregular, and usually possess lobes. The diameter of the cells fall in the range of 0.8-1 μm, with little size variation. Sulfolobus acidocaldarius possess a mechanism of replication homologous to the eukaryotic ESCRT. Sulfolobus acidocaldarius is a facultative autotroph. When growing autotrophically this organism oxidises sulfur to sulfate, while fixating carbon from carbon dioxide. The doubling time of cultures growing on sulfur alone falls between 36.8-55.3h. This species can also grow on complex organic substrates. When growing on 0.1% yeast extract the growth is faster, and the doubling times are between 6.5 and 8h. In 2005 the complete genome of Sulfolobus acidocaldarius strain DSM639 was published. The genome of this archaeon is composed of a single circular chromosome with 2,225,959 bp, with a G+C content of 36.7%. The authors predicted 2292 protein-coding genes. The genome of Sulfolobus acidocaldarius is very stable, with little, if any, rearrangements due to mobile elements. The authors found the genes necessary for the synthesis of purines and pyrimidines, as well as for all amino acids except for selenocysteine. Genes for glucose metabolism suggest the existence of two alternative pathways.