the type genus of Rhizobiaceae; usually occur in the root nodules of legumes; can fix atmospheric oxygen

(pl: rhizobia)  Prokaryote able to establish symbiotic relationship with leguminous plants, as a result of which elemental nitrogen is fixed or converted to ammonia. See  nitrogen fixation.

A genus of heterotrophic soil bacteria capable of forming symbiotic nodules on the roots of legume plants to fix atmospheric nitrogen.