rhodocyclus purpureus rhodocyclus purpureus rhodocyclus purpureus is a species of bacteria. its cells are half-ring-shaped and ring-shaped before cell division; the half-rings being 0.6 to 0.7 μm wide and 2.5 to 3.0 μm long. open or compact coils of variable length are also formed. it is facultatively aerobic and its type strain is “ames” 6770 (= dsm 168). rhodocyclus purpureus scientific classification domain: bacteria phylum: pseudomonadota class: betaproteobacteria order: rhodocyclales family: rhodocyclaceae genus: rhodocyclus species: r. purpureus binomial name rhodocyclus purpureuspfennig, 1978