A novel microbe was isolated from a geothermal vent in Yang-Ming National Park in northern Taiwan. This spherical microbe with mean cell diameter of 1·1·0·2 μm is a facultatively chemolithoautotrophic archaeon that grows on elemental sulfur and reduced sulfur compounds. The optimal pH and temperature for growth are 4·0 (pH range 2·0-6·0) and 80 °C (temperature range 65-95 °C). Its membranes contain the lipids calditoglycerocaldarchaeol and caldarchaeol, which are common to other members of the Sulfolobaceae. Like Sulfolobus acidocaldarius, Sulfolobus shibatae and Sulfolobus solfataricus, the new isolate utilizes sugars and amino acids effectively as sole carbon sources. The G+C content of the genomic DNA was 42 mol%. DNA of the isolate hybridized weakly to the DNA of other Sulfolobus species. Phylogenetic analysis of the 16S rRNA indicated that the new isolate represents a deep branch within the genus Sulfolobus. On the basis of these properties, the new isolate appears to represent a new species of Sulfolobus, for which the name Sulfolobus yangmingensis sp. nov. is proposed. The type strain is strain YM1T.
A hyperthermophilic archaeon, strain AL585T, was isolated from a deep-sea hydrothermal vent located on the East Pacific Rise at latitude 13 ° N and a depth of 2650 m. The isolate was a strictly anaerobic coccus with a mean cell diameter of 1 μm. The optimum temperature, pH and concentration of sea salt for growth were 95 °C, 7·5 and 30 g l-1. Under these conditions, the doubling time and cell yield were 0·5 h and 5 x 108 cells ml-1. Strain AL585T grew preferentially in media containing complex proteinaceous carbon sources, glucose and elemental sulfur. The G+C content of the DNA was 47 mol%. Sequencing of the 16S rDNA gene showed that strain AL585T belonged to the genus Pyrococcus and was probably a new species. This was confirmed by total DNA hybridization. Consequently, this strain is described as a new species, Pyrococcus glycovorans sp. nov.