Gerard S. Saddler and John F Bradbury

Xan.tho'mo.nas or'nas.* Gr. adj. xanthus yellow; Gr. fem. n. monas unit, monad; M.L. fem. n. Xanthomonas yellow monad.

Straight rods, 0.4-0.6 X 0.8-2.0 lm, mostly single or in pairs, occasionally short chains, filaments rarely seen. Gram negative. Do not produce poly-ß-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 "xantho-monadins". A characteristic extracellular acidic heteropolysac-charide called xanthan is produced by most strains giving the

*Editorial Note: The genus Fulvimonas was described after the cut-off date for inclusion of new taxa in this volume of the Manual; hence, there is no separate chapter devoted to it. Characteristics of the genus Fulvimonas are given in Table BXII.y.17 of the chapter describing the Genus Xanthomonas.

*Editorial Note: The first pronunciation is according to strict Latin usage while the second is more commonly used.

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-sor-bitol, meso-inositol, or meso-erythritol. Metabolic activity is shown in Biolog GN microplate tests with D-fructose, D-glucose, D-man-nose and methylpyruvate, but not with a-cyclodextrin, adonitol, D-arabitol, meso-erythritol, meso-inositol, xylitol, D-glucosaminate, y-hydroxybutyrate, itaconate, sebacate, L-ornithine, L-pyrogluta-mate, D-serine, D,L-carnitine, y-aminobutyrate, phenylethylam-ine, putrescine, 2-aminoethanol, or 2,3-butanediol. L-asparagine, L-glutamine, and glycine cannot be used as sole sources of both

TABLE BXII.y.17. Differential characteristics of the genera in the family Xanthomonaclacecu?

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