Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         [crown] Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
           Domain Bacteria Woese et al. 1990 [paraphyletic?]
             Superphylum "Proteobacteria" Craig et al. 2010
               Phylum "Alphaproteobacteria" Garrity et al., 2006 [monotypic]
                 Class Alphaproteobacteriaᵀ Garrity et al. 2006
                   Order Rhizobiales Kuykendall 2006
                     Family Bradyrhizobiaceae Garrity et al. 2006
                       Genus Nitrobacter Winogradsky 1892 (Approved Lists 1980)
                         1 Nitrobacter alkalicus Sorokin et al. 1999
                         2 Nitrobacter hamburgensis Bock et al. 2001
                         3 Nitrobacter vulgaris Bock et al. 2001
                         4 Nitrobacter winogradskyi Winslow et al. 1917 (Approved Lists 1980)