rhodocyclus rhodocyclus rhodocyclus is a genus of gram-negative bacteria from the family of rhodocyclaceae which belongs to the class of betaproteobacteria. rhodocyclus scientific classification domain: bacteria phylum: pseudomonadota class: betaproteobacteria order: rhodocyclales family: rhodocyclaceae genus: rhodocycluspfennig 1978 type species rhodocyclus purpureus species rhodocyclus gelatinosus rhodocyclus purpureus rhodocyclus tenuis