"Enterobacteriales".

Gram-negative straight rods, 0.3−1.0 × 1.0−6.0 µm, except for Arsenophonus, which is 7-10 lm in length. Motile by peritrichous flagella, except for Tatumella, or nonmotile. Do not form endospores or microcysts; not acid-fast. Grow in the presence and absence of oxygen. Grow well on peptone, meat extract, and usually MacConkey's medium, except for Calymmatobacterium and insect symbionts, which have not been cultivated. Most grow well at 22-35†C; optimal growth and maximal biochemical capacity of a number of genera (Yersinia, Hafnia, Xenorhabdus, Photorhabdus, and many erwiniae) occurs at 25-28†C. Some grow on dglucose as the sole source of carbon; some require vitamins and/or amino acids. Chemoorganotrophic; having both a respiratory and a fermentative metabolism. Acid and visible gas are often produced during fermentation of d-glucose, other carbohydrates and polyhydroxyl alcohols. Not halophilic. Most are catalase-positive, except for Shigella dysenteriae O group 1 and Xenorhabdus. Most are oxidase negative, except for Plesiomonas. Most reduce nitrate to nitrite, except Saccharobacter fermentatus (Yaping et al., 1990) and some strains of Erwinia and Yersinia. [ABSTRACT FROM AUTHOR]

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