organisms see Clade Biota Wagner 2004 [Wiemann, de Queiroz, Rowe, Planavsky, Anderson, Gogarten, Turner & Gauthier 2020]
   Kingdom Monera Haeckel 1866 see Domain Bacteria Woese et al. 1990
     Phylum "Nitrogen-Fixing Aerobic Bacteria" see Phylum Proteobacteria Garrity and Holt 2001
       1 Genus Azotobacter Beijerinck 1901 (Approved Lists 1980)
       2 Genus Azomonas Winogradsky 1938 (Approved Lists 1980)
       3 Genus Beijerinckia Derx 1950 (Approved Lists 1980)
       4 Genus Derxia Jensen et al. 1960 (Approved Lists 1980)
       5 Genus Rhizobium Frank 1889 (Approved Lists 1980)