rhizobium leguminosarum rhizobium leguminosarum 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. r. leguminosarum has been very thoroughly studied—it has been the subject of more than a thousand publications. rhizobium leguminosarum scientific classification domain: bacteria phylum: pseudomonadota class: alphaproteobacteria order: hyphomicrobiales family: rhizobiaceae genus: rhizobium species: r. leguminosarum binomial name rhizobium leguminosarum(frank 1879) frank 1889 (approved lists 1980) type strain atcc 10004lmg 14904strain 3hoq18usda 2370 biovars symbiovar trifolii symbiovar viciae synonyms rhizobium trifolii dangeard 1926 (approved lists 1980) morphology rhizobium leguminosarum is a gram-negative, motile, rod-shaped, aerobic bacterium. common biovars rhizobium leguminosarum biovar trifolii, and r. leguminosarum biovar viciae are the most commonly studied biovars of r. leguminosarum, with certain studies seemingly treating r. trifolii as its own species. fatty acid synthesis rhizobium leguminosarum's acyl carrier protein differs from most acps by having a c-terminus extension. this acp is also used in the synthesis of unusually long acps which themselves are then used in the synthesis of the r. leguminosarum nod factor. uses r. leguminosarum is widely used in the inoculation of legume seeds. the sv. trifolii strain u204 is commercially used to inoculate white and red clover in particular, but better strains for this purpose are being developed. research has been carried out into the role that r. leguminosarum could play in promoting growth of canola and lettuce.