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DesulfobulbusRANK: GenusTAXONOMY: Bacteria -> Proteobacteria -> delta/epsilon subdivisions -> Deltaproteobacteria -> Desulfobacterales -> Desulfobulbaceae -> Desulfobulbus OVERVIEW: Cells are ovoid to rod shaped, or lemon shaped with pointed ends, 0.6–1.3 × 1.5–3.5 μm. Occur singly, in pairs, or in chains. Spore formation is not observed. Gram negative. Cells are motile by a single polar flagellum, or are nonmotile. Strictly anaerobic, having both a respiratory and a fermentative type of metabolism. Chemoorganotrophs, using propionate, lactate, pyruvate, ethanol, or 1-propanol as electron donors and also as carbon sources; organic compounds are incompletely oxidized to acetate. H2 can be used as electron donor in the presence of acetate as organic carbon source (chemolithoheterotrophic growth). Sulfate and often sulfite or thiosulfate serve as terminal electron acceptors and are reduced to H2S. Sulfur is never reduced. In the absence of an external electron acceptor, growth may occur by fermentation of lactate, pyruvate, and ethanol (+ CO2), malate, or fumarate. The optimum pH range for growth is 6.6–7.5. The optimum temperature range for growth is 25–40°C. Thermophilic species are not known. Media containing a reductant and p-aminobenzoate are required for growth. Colonies in anaerobic agar media are whitish to grayish and smooth. All described species contain desulforubidin as sulfite reductase. Occur in anoxic parts of freshwater, brackish water, and marine habitats; also isolated from rumen contents, animal dung, and sewage sludge.The mol% G + C of the DNA is: 50–60.Type species: Desulfobulbus propionicus
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