Rhizobium leguminosarum is a bacterium which lives in a mutualistic symbiotic relationship with legumes, and has the ability to fix free nitrogen from the air.

[2] Rhizobium leguminosarum is a Gram-negative, motile, rod-shaped, aerobic bacterium.

[4] Rhizobium leguminosarum's acyl carrier protein differs from most ACPs by having a C-terminus extension.

[5] R. leguminosarum is widely used in the inoculation of legume seeds.

[6] Research has been carried out into the role that R. leguminosarum could play in promoting growth of canola and lettuce.