[organisms] see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Domain Bacteria Woese et al. 1990
     Phylum "Proteobacteria" Garrity et al. 2005 see Superphylum Proteobacteria Craig et al. 2010
       Class Alphaproteobacteria Garrity et al. 2006
         Order Rhizobiales Kuykendall 2006
           Family Bradyrhizobiaceae Garrity et al. 2006
             Genus Nitrobacter Winogradsky 1892 (Approved Lists 1980)
               1 Nitrobacter winogradskyi Winslow et al. 1917 (Approved Lists 1980)
               2 Nitrobacter alkalicus Sorokin et al. 1999
               3 Nitrobacter hamburgensis Bock et al. 2001
               4 Nitrobacter vulgaris Bock et al. 2001