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ThiovulumRANK: GenusTAXONOMY: Bacteria -> Proteobacteria -> delta/epsilon subdivisions -> Epsilonproteobacteria -> Campylobacterales -> Helicobacteraceae -> Thiovulum OVERVIEW: Cells are round to ovoid, 5–25 μm in diameter. Cytoplasm is often concentrated at one end of the cell, with the remaining space being occupied by a large vacuole. Cytoplasm normally contains orthorhombic sulfur inclusions, which are generally concentrated at one end and often almost filling cells completely (Figure 1). The amount of sulfur present in the cells varies with the H2S supply, and cells may be temporarily fully devoid of sulfur inclusions. The number of greenish bodies (up to 5 μm in diameter), thought to be storage material, increases with decreasing numbers of sulfur globules (Hinze, 1913). Cells are rapidly motile by peritrichous flagella (Figure 2; de Boer et al., 1961). Swimming velocity of over 600 μm s-1, some of the highest recorded in the bacterial world (Garcia-Pichel, 1989). Forward movement is accompanied by rotation around the long axis. Unlike most motile bacteria, Thiovulum cells do swim backwards or tumble. Cells possess a fibrillar, or antapical organelle at the posterior end of the cell. Its function is to secrete a slime stalk or thread (Figure 2) which is used by cells to attach to solid surfaces. No resting stages are known. Type species: Thiovulum majus |