Al.lo.rhi.zo' bi.um. Gr. adj. allos other; M.L. neut. n. Rhizobium a bacterial generic name; M.L. neut. n. Allorhizobium the other Rhizobium, to refer to the fact that it is phylogenetically separate from other Rhizobium species.

Proteobacteria / Alphaproteobacteria / Rhizobiales / Rhizobiaceae / Allorhizobium

Rods 0.5–0.7 × 2.0–4.0 µm. Nonsporeforming. Gram negative. Aerobic, having a strictly respiratory type of metabolism with oxygen as the terminal electron acceptor. Relatively fast growing; colonies 0.5–3.0 mm develop in 1–2 days on yeast–mannitol–mineral salts agar, and pronounced turbidity develops after 1–2 days in agitated broth media. Chemoorganotrophic. A wide range of carbohydrates, organic acids, and amino acids are used as sole carbon sources for growth. Ketolactose is not produced from lactose. Growth on carbohydrate media is usually accompanied by extracellular polysaccharide production. At the molecular level, the genus can be distinguished from related species in other genera by SDS-PAGE whole cell protein analysis, ITS PCR-RFLP, and 16S rRNA gene sequencing. Initiates the production of root nodules, in which the bacteria occur as nitrogen-fixing intracellular symbionts. Exhibits specificity to certain temperate-zone and tropical-zone leguminous plants (family Leguminoseae).

The mol% G + C of the DNA is: 60.1.

Type species: Allorhizobium undicola De Lajudie, Laurent-Fu-lele, Willems, Torck, Coopman, Collins, Kersters, Dreyfus and Gillis 1998a, 1288.