Domain Bacteria Woese et al. 1990
   Phylum Proteobacteria Garrity and Holt 2001 see Phylum Proteobacteria Garrity et al. 2005
     Class "Betaproteobacteria" Garrity et al. 2001 nom. ined. see Class Betaproteobacteria Garrity et al. 2006
       1 Order "Burkholderiales" see Order Burkholderiales Garrity et al. 2006
       2 Order "Hydrogenophilales" nom. inval. see Order Hydrogenophilales Garrity et al. 2006
       3 Order "Methylophilales" nom. inval. see Order Methylophilales Garrity et al. 2006
       4 Order "Neisseriales" see Order Neisseriales Tønjum 2006
       5 Order "Nitrosomonadales" see Order Nitrosomonadales Garrity et al. 2006
       6 Order "Rhodocyclales" see Order Rhodocyclales Garrity et al. 2006