RANK: Genus

TAXONOMY: cellular organisms -> Bacteria -> Proteobacteria -> Alphaproteobacteria -> Rhodospirillales -> Acetobacteraceae -> Gluconobacter


Ellipsoidal to rod-shaped cells, 0.5–1.0 × 2.6–4.2 µm, occurring singly and/or in pairs, rarely in chains. The formation of enlarged, irregular cells may occur. Endospores are not formed. Motile or nonmotile; if motile, the cells have 3–8 polar flagella. Gram negative. Obligately aerobic, having a strictly respiratory type of metabolism with oxygen as the terminal electron acceptor. Metabolism is never fermentative. Optimal temperature for growth is 25–30°C. Optimal pH for growth is 5.0–6.0; most strains will grow at pH 3.5. Catalase positive, oxidase negative. Negative for nitrate reduction, gelatin liquefaction, indole production, and H2S formation. Oxidize ethanol to acetic acid. Do not oxidize acetate or lactate to CO2 and H2O. Gluconobacter strains generally produce acid during growth on fructose, glucose, xylose, and maltose and tolerate up to 10% glucose. Ketogenesis occurs from polyalcohols (for example, dihydroxyacetone from glycerol). All strains produce 2-ketogluconic acid from d-glucose, and the majority of strains also form 5-ketogluconic acid. Formation of water-soluble brown pigment is correlated with the production of 2,5-diketogluconic acid and γ-pyrones from d-glucose. Most strains form acid from ethanol, d-mannitol, d-fructose, d-glucose, d-maltose, glycerol, and d-xylose. Few strains produce acid from lactose. The best carbon sources for growth are d-mannitol and d-glucose. Possesses ubiquinone of the Q-10 type as major quinone. The predominant fatty acid in Gluconobacter is the C18:1 ω7 straight-chain unsaturated acid. Isolated from sugar-rich environments such as fruits and flowers, honey bees, grapes and wine, palm sap, cocoa wine, cider, beer, and soft drinks.The mol% G + C of the DNA is: 52–64.Type species: Gluconobacter oxydans