The major ether-type lipid structures of Sulfolobus acidocaldarius (ATCC33909) were composed of caldarchaeol and calditoglycerocaldarchaeol. However, the characterization by nuclear magnetic resonance spectroscopy and mass spectrometry showed that the structure of calditol in calditoglycerocaldarchaeol is not nonitol, 2-(1',2',3'-trihydroxypropyl)1,2,3,4,5,6-hexahydroxyhexane, but 2-hydroxymethyl-1-(2,3-dihydroxypropoxy)2,3,4,5-cyclopentanetet raol with an ether linkage in the molecule. Such an intermolecular ether linkage was resistant to BCl3 treatment, but nonresistant to 57% HI degradation treatment conducted at 100 degrees C for 60 h, producing 2-hydroxymethyl-1,2,3,4,5-cyclopentanepentaol from calditol as reaction product. Further, it was confirmed that the structure of calditol is essentially a derivative of glycerol, and hydrocarbon chains were conjugated to the glycerol-like site in the structure. The calditol with an ether linkage in the molecule suggested an important role regarding the properties of heat-resistance and acid-resistance observed in Sulfolobales.

Ribonuclease F1, the guanine-specific ribonuclease of Fusarium moniliforme, was purified to homogeneity by a combination of ethanol fractionation, affinity chromatography and DEAE-cellulose column chromatography. The adsorbent for the affinity chromatography was synthesized by the coupling of periodate-oxidized guanosine 5'-monophosphate to aminohexyl agarose followed by sodium borohydride reduction. Ribonuclease F2, the minor component, was also purified to near homogeneity by the same procedure. Ribonucleases F1 and F2 had the same molecular weight (about 11,000) as determined by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. They also showed the same amino acid composition and differed only in the isoelectric point: 4.10 for F1 and 3.96 for F2.

Three isolates of spherical thermoacidophilic archaebacteria (strains TA-1, TA-2 and N-8) were obtained from acidic hot springs at Hakone and Noboribetsu in Japan. We have studied the isolates using electron microscopy, Gram staining, sensitivity to lysozyme, growth conditions, lipid compositions, SDS-PAGE patterns of whole-cell proteins, DNA base composition and partial 16S rRNA sequences. These characteristics of the isolates were compared with those of the type strains, Sulfolobus acidocaldarius, Sulfolobus solfataricus, Acidianus brierleyi, Acidianus infernus, Metallosphaera sedula and Desulfurolobus ambivalens. Comparative studies indicated that the isolate TA-1 was novel species of either Sulfolobus or Acidianus, the isolate TA-2 belonged to the genus Metallosphaera, and the isolate N-8 belonged to the same species of S. acidocaldarius isolated from Yellowstone.A comparative sequence study of the 16S rRNAs showed that living organisms can be divided into three kingdoms: the traditional eubacterial and eukaryotic kingdoms and the newly recognized archaebacterial kingdom (22,23). Although archaebacteria exhibit a prokaryotic cell structure and organization, they show distinguishing and unique features (1,10,11,(14)(15)(16).From acidic hot springs in Japan, three isolates of spherical thermoacidophilic archaebacteria (strains TA-1, TA-2 and N-8) were obtained. Total lipid composition analysis and preliminary results of growth temperature and pH showed that these three strains belong to the order Sulfolobales (19,20).

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