RESUMO
An extremely thermoacidophilic isolate K4-1 was obtained from an acidic hot spring in Teng- chong Rehai, Yunnan province. Morphology, growth characteristics, utilization of carbon compounds, en- ergy sources and 16S rRNA gene sequence of K4-1 were studied. Cells of K4-1 are irregular cocci with monotrichous flagella. The strain grew aerobically in either a lithotrophic or a heterotrophic mode. Growth on elemental sulfur occurred through oxidation of sulfur. It grew optimally at 75?C and pH 3.5. On the basis of 16S rRNA gene sequence similarity, strain K4-1 was shown to belong to genus Sulfolobus, being related to the type strains of genus Sulfolobus (86.6%~94.3% similarity), and being most closely related to strain Sulfolobus tengchongensis RT8-4 (98.9% similarity). The GenBank accession number of strain K4-1 16S rRNA gene sequence is EU729124.