rhizobium

noun, plural rhi·zo·bi·a [rahy-zoh-bee-uh] /raɪˈzoʊ bi ə/. Bacteriology.

1. any of several rod-shaped bacteria of the genus Rhizobium, found as symbiotic nitrogen fixers in nodules on the roots of the bean, clover, etc.

noun plural -bia (-bɪə)

1. any rod-shaped bacterium of the genus Rhizobium, typically occurring in the root nodules of leguminous plants and able to fix atmospheric nitrogenSee also nitrogen fixation