[Ultrastructural organization of Sulfobacillus thermosulfidooxidans cells and spores]

The ultrastructural organization of Sulfobacillus thermosulfidooxidans cells and spores was studied by electron microscopy using the techniques of negative contrasting and thin sections. The cell wall was found to be 20--25 nm thick and to consist of a rigid layer bound to the cytoplasmic membrane with crosspieces. A microcapsule about 20 nm thick having an ordered structure is closely associated with the cell wall. A layer of slime which can reach 0.2--0.3 mcm and more in thickness is located at the outside. The flagellar apparatus is absent. The membranous apparatus has a peculiar structure. On thin cross-sections of intact cells, the cytoplasmic membrane profile is stained sharply asymmetrically. Numerous membrane invaginates located in the cytoplasm are morphologically simple vesicular formations and structures of a rather complicated unusual configuration. Lamella-like structures are also encountered, which divide, as it were, the cytoplasm into compartments. The contours of the intracellular membranes look thicker as compared with the cytoplasmic membrane. Small vesicular formations are occasionally encountered in the periplasm. Vast areas with inclusions of unknown chemical nature having a fine granular structure are located in the cytoplasm. The process of sporogenesis comprises the same stages as in Bacillus, and spores have a strucutre typical of the endospores.