rhodobium (bacterium) rhodobium (bacterium) rhodobium is a genus of purple non-sulfur bacteria. the cells are rod-shaped and reproduce by budding, as in many other members of the hyphomicrobiales. rna trees separate it from the others, however, and it is given its own family. r. orientis, the type species, was isolated from seawater in 1995. it is capable of photosynthetic hydrogen production via the nitrogenase enzyme. rhodobium scientific classification domain: bacteria phylum: pseudomonadota class: alphaproteobacteria order: hyphomicrobiales family: rhodobiaceaegarrity et al. 2006 genus: rhodobiumhiraishi et al. 1995 species r. gokarnense srinivas et al. 2007 r. orientis hiraishi et al. 1995