A.ce.to.bac' ter. L. n. acetum vinegar; M.L. n. bacter masc. equivalent of Gr. neut. n. bakterion rod; M.L.masc. n. Acetobacter vinegar rod.

Proteobacteria / Alphaproteobacteria / Rhodospirillales / Acetobacteraceae / Acetobacter

Cells ellipsoidal to rod shaped, straight or slightly curved, 0.6–0.9 × 1.0–4.0 µm, occurring singly, in pairs, or in chains. Motile or nonmotile; if motile, the flagella are peritrichous. Endospores are not formed. Gram negative. Obligately aerobic; metabolism is strictly respiratory with oxygen as the terminal electron acceptor. Never fermentative. Form pale colonies; most strains produce no pigments. A minority of strains produces brown water-soluble pigments or show pink colonies due to the production of porphyrins. Usually catalase positive. Oxidase negative. Absence of gelatin liquefaction, indole production, and H₂S formation. Oxidizes ethanol to acetic acid. Acetate is oxidized to CO₂ and H₂O. The best carbon sources for growth are ethanol, glycerol, and glucose. Some strains require p-aminobenzoic acid, niacin, thiamin, or pantothenic acid as growth factors. Neither lactose nor starch is hydrolyzed. No production of 2,5-diketo-D-gluconate from D-glucose. Chemoorganotrophs. Optimum temperature is 30°C. Some strains reduce nitrate to nitrite. The pH optimum for growth is 4.0–6.0. Possesses ubiquinone of the Q-9 type as major quinone. The predominant fatty acid in Acetobacter is the C_{18:1 ω7} straight-chain unsaturated acid. Acetobacter species occur in flowers, fruits, palm wine, vinegar, kefir, and fermented foods and can cause infections in grape wine, sake, tequila, cocoa wine, cider, beer, and fermented meat. Acetobacter is not known to have any pathogenic effect toward humans and animals.

The mol% G + C of the DNA is: 50.5–60.3.

Type species: Acetobacter aceti (Pasteur 1864) Beijerinck 1898 (Mycoderma aceti Pasteur 1864, 125; Acetobacter aceti subsp. aceti (Pasteur 1864) De Ley and Frateur 1974.)