rhizobium pisi rhizobium pisi rhizobium pisi is a root nodule bacterium. rhizobium pisi scientific classification domain: bacteria phylum: pseudomonadota class: alphaproteobacteria order: hyphomicrobiales family: rhizobiaceae genus: rhizobium species: r. pisi binomial name rhizobium pisiramírez-bahena et al. 2008 type strain dsm 30132ncib 11478ncimb 11478 biovars symbiovar trifolii symbiovar viciae