rhodobacterales rhodobacterales rhodobacterales are an order of the alphaproteobacteria. rhodobacterales scientific classification domain: bacteria phylum: pseudomonadota class: alphaproteobacteria order: rhodobacteralesgarrity et al. 2006 families neomegalonemataceae hördt et al. 2020 paracoccaceae liang et al. 2022 roseobacteraceae liang et al. 2021 gene transfer agents are viruslike elements produced by rhodobacterales which transfer dna and may be an important factor in their evolution. etymology from greek rhodon, the rose, and bakterion, a rod. this refers to the colour of aerobic phototrophic cultures of this order of bacteria which can be pink or red due to the production of carotenoids.