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XanthomonasRANK: GenusTAXONOMY: cellular organisms -> Bacteria -> Proteobacteria -> Gammaproteobacteria -> Xanthomonadales -> Xanthomonadaceae -> Xanthomonas OVERVIEW: Straight rods, 0.4–0.6 × 0.8–2.0 μm, mostly single or in pairs, occasionally short chains, filaments rarely seen. Gram negative. Do not produce poly-β-hydroxybutyrate inclusions, nor have sheaths, prosthecae, or resting stages. Motile by a single polar flagellum. Obligately aerobic, having a strictly respiratory type of metabolism with oxygen as the terminal electron acceptor. No denitrification or nitrate reduction occurs. Colonies are usually yellow, smooth and butyrous, mucoid or viscid. The pigments are highly characteristic brominated aryl polyenes or “xanthomonadins”. A characteristic extracellular acidic heteropolysaccharide called xanthan is produced by most strains giving the viscous consistency. Growth is inhibited by 6% NaCl, 30% glucose, 0.01% lead acetate, methyl green, or thionin, and by 0.1% (and usually by 0.02%) triphenyl tetrazolium chloride. Catalase positive; oxidase negative or weak; urease not produced. H2S is usually produced, but not indole or acetoin. Acid is not produced in litmus milk or purple milk. Chemoorganotrophic; able to use various carbohydrates and salts of organic acids as sole carbon sources. Small amounts of acid are produced from many carbohydrates, but not from l-rhamnose, adonitol, sorbose, d-sorbitol, meso-inositol, or meso-erythritol. Metabolic activity is shown in Biolog GN microplate tests with d-fructose, d-glucose, d-mannose and methylpyruvate, but not with α-cyclodextrin, adonitol, d-arabitol, meso-erythritol, meso-inositol, xylitol, d-glucosaminate, γ-hydroxybutyrate, itaconate, sebacate, l-ornithine, l-pyroglutamate, d-serine, d,l-carnitine, γ-aminobutyrate, phenylethylamine, putrescine, 2-aminoethanol, or 2,3-butanediol. l-asparagine, l-glutamine, and glycine cannot be used as sole sources of both carbon and nitrogen. Among the nine fatty acids that predominate in whole cell preparations are 9-methyl decanoic acid (C11:0 iso), 3-hydroxy-9-methyl decanoic acid (C11:0 iso 3OH), and 3-hydroxy-11-methyl dodecanoic acid (C13:0 iso 3OH), which are highly characteristic of this genus. The ubiquinone that is present has eight isoprene units. Spermidine is the main polyamine; spermine is usually detectable, but not 2-hydroxyputrescine or 1,3-diaminopropane. Species so far described are plant pathogens or are plant associated.The mol% G + C of the DNA is: 63.3–69.7 (Tm).Type species: Xanthomonas campestris
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