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ZymomonasRANK: GenusTAXONOMY: cellular organisms -> Bacteria -> Proteobacteria -> Alphaproteobacteria -> Sphingomonadales -> Sphingomonadaceae -> Zymomonas OVERVIEW: Rod-shaped cells with rounded ends, occasionally ellipsoidal, usually in pairs, 2–6 × 1.0–1.4 µm. Gram negative. Usually non-motile; if motile, they possess one to four polar flagella. Motility may be lost spontaneously. Facultatively anaerobic; some strains are obligately anaerobic. Optimum temperature 25–30°C. Colonies on the standard medium1 are glistening, regularly edged, white to cream colored, 1–2 mm in diameter after 2 d at 30°C. Oxidase negative. Chemoorganotrophic, growing on and fermenting 1 mol of glucose or fructose to almost 2 mol of ethanol, 2 mol of CO2, and some organic acids such as lactic acid. Some strains may also utilize sucrose, but other carbon sources are not used. Gluconate can be degraded but does not serve as sole carbon or energy source (Strohdeicher et al., 1 988). Sorbitol and gluconolactone are formed when grown on sucrose or mixtures of glucose and fructose by a so far unique enzyme, glucose-fructose oxidoreductase. Membranes contain pentacyclic triterpenoids of the hopane series (Sahm et al., 1 993). Gelatinase negative. Nitrates are not reduced and indole is not produced. Zymomonas tolerates 5% ethanol and is acid tolerant, growing at pH 3.5–7.5. Good growth is obtained only when a mixture of amino acids is present in the medium, but no one amino acid is essential. All strains require biotin and pantothenate. Zymomonas occurs as a spoiler in beers, ciders, and perries; as fermenting agents in Agave sap, palm sap, and sugarcane juice; and on honeybees and in ripening honey. The mol% G + C of the DNA is: 47.5–49.5.Type species: Zymomonas mobilis |