We have isolated and identified two microbial strains, strain DBS and strain F, from Geothermal Valley in Bei-tou District, Taipei, located in northern Taiwan. Strain DBS and strain F are hyperthermophilic aerobic archaea, which appeared as irregular cocci in shape with a diameter about 1.0-2.0μm, with no pili- or flagella-like structure. The optimal temperature and pH for growth of strain DBS are 3.0 and 80℃, respectively. Both strains are facultative emolithoautotrophic that not only utilize many sugars and amino acids as the sole carbon sources, but also grow on elemental sulfur and reduced sulfur compounds. The G+C contents for strain DBS and strain F are 51.7%
and 40.3%, respectively. Phylogenetic analysis of the 16S rRNA sequences from various Sulfolobaceae species shows that the two new strains are distinct from other thermophilic species, but are clearly related to the genus Sufolobus. Using DNA-DNA hybridization method, the homologies between strain DBS and strain F with other related Sulfolobus species are not significantly high. Considering the morphology, physiological properties, nutritional requirements and phylogenetic analyses based on 16S rRNA gene sequencing, the two strains are described as novel thermal species
pertaining to the genus Sulfolobus. The two type strains are named Sulfolobus beitoneusis and Sulfolobus vallishades.
