rhodospirillales rhodospirillales the rhodospirillales are an order of pseudomonadota. purple sulfur bacteria scientific classification domain: bacteria phylum: pseudomonadota class: alphaproteobacteria order: rhodospirillalespfennig and trüper 1971 (approved lists 1980) families acetobacteraceae (ex henrici 1939) gillis and de ley 1980 azospirillaceae hördt et al. 2020 geminicoccaceae proença et al. 2018 kiloniellaceae wiese et al. 2009 reyranellaceae hördt et al. 2020 rhodospirillaceae pfennig and trüper 1971 (approved lists 1980) rhodovibrionaceae hördt et al. 2020 stellaceae hördt et al. 2020 terasakiellaceae hördt et al. 2020 thalassobaculaceae hördt et al. 2020 thalassospiraceae hördt et al. 2020 zavarziniaceae hördt et al. 2020 synonyms kiloniellales wiese et al. 2009 notable families the acetobacteraceae comprise the acetic acid bacteria, which are heterotrophic and produce acetic acid during their respiration. the rhodospirillaceae include mainly purple nonsulfur bacteria, which produce energy through photosynthesis. phylogeny the currently accepted taxonomy is based on the list of prokaryotic names with standing in nomenclature (lpsn). the phylogeny is based on whole-genome analysis. rhodospirillaceae zavarziniaceae azospirillaceae stellaceae reyranellaceae acetobacteraceae rhodospirillaceae thalassospiraceae terasakiellaceae kiloniellaceae rhodovibrionaceae thalassobaculaceae outgroup rhodothalassiales notes the geminicoccaceae are not included in this phylogenetic tree.