Abstract
Several strains of thermoacidophilic archaea were isolated from a water sample taken from the hot spring "Kamado-Jigoku 4 Chome" at Beppu in Oita, Japan. The original temperature of the hot spring was 78.3℃, and the pH was 2.48. In the original water sample, spherical microbes with a diameter of about 1μm were mainly observed by fluorescence microscopy.
An isolate (tentatively designated as BK4-K1) grows optimally at 70〜75℃ and pH 2〜3. Although the shape of the strain BK4-K1 was observed as spherical with a diameter of about 1μm by optical microscopy, it was observed as irregular (0.8〜1.2μm) by scanning electronmicroscopy. The strain was gram-negative and nonmotile. Susceptibility to antibiotics indicated that the strain BK4-K1 belongs to archaea domain. Lack of long chain fatty acids in the total cellular lipid also supported the classification. The strain BK4-K1 was identified as being of a close relative of the genus Sulfolobus, on the basis of fair agreement of its total characteristics with those of the archaeon, Sulfolobus acidocaldarius. The TLC analysis, however, showed that the strain has different total cellular lipid constituents from those reported for the close relative of the genus Sulfolobus isolated from Owaku-dani at Hakone in Japan.
