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DesulfococcusRANK: GenusTAXONOMY: Bacteria -> Proteobacteria -> delta/epsilon subdivisions -> Deltaproteobacteria -> Desulfobacterales -> Desulfobacteraceae -> Desulfococcus OVERVIEW: Cells are spherical or lemon-shaped, 1.4–2.3 μm in diameter. Occur singly or in pairs. Spore formation is not observed. Cells stain Gram negative and often contain granules of poly-β-hydroxybutyrate. The cells are motile by a single polar flagellum, or are nonmotile. Slime capsules may occur. Strict anaerobes with a respiratory and fermentative type of metabolism. Nutritionally versatile. Many species use formate and higher monocarboxylic acids up to C16, lactate, pyruvate, and alcohols as electron donors and as carbon sources. Acetone and phenyl-substituted organic acids may be utilized. These compounds are completely oxidized to CO2 via the anaerobic C1 pathway (carbon monoxide dehydrogenase pathway, Wood pathway). Sulfate and other oxidized sulfur compounds serve as terminal electron acceptors and are reduced to H2S. In the absence of an external electron acceptor, slow growth occurs by fermentation of lactate or pyruvate to acetate and propionate. The optimal temperature range for growth is 28–35°C. The optimal pH range for growth is 6.7–7.6. Growth occurs in simple, defined media containing a reductant (usually sulfide) and vitamins. Colonies in anoxic agar media are whitish to yellowish (with sometimes grayish appearance) and tend to be slimy. Desulfoviridin is present in all species. Thermophilic species have not been described. Occur in anoxic mud of freshwater, brackish water, and marine habitats; also occur in sludge of anaerobic sewage digestors.The mol% G + C of the DNA is: 56–57.Type species: Desulfococcus multivorans |