azospira restricta azospira restricta azospira restricta is a species of nitrogen-fixing bacteria. it is a root bacteria and together with azospira oryzae they are the two species in the genus. it is gram-negative, non-spore-forming, with straight to curved rod-shaped cells with a single polar flagellum. the type strain is sua2t (=nrrl b-41660t=dsm 18626t=lmg 23819t). azospira restricta scientific classification domain: bacteria phylum: pseudomonadota class: betaproteobacteria order: rhodocyclales family: rhodocyclaceae genus: azospira species: a. restricta binomial name azospira restrictabae et al., 2007