Azotobacter nigricans achromogenes Thompson and Skerman 1981 Azotobacter nigricans achromogenes Thompson and Skerman 1981 Universal Root Woese et al. 1990 Bacteria (None 2015) Woese et al. 1990 Proteobacteria (sic) Garrity et al. 2021 Pseudomonadota corrig. Garrity et al. 2021 Alphaproteobacteriota (sic) Garrity et al. 2021 Gammaproteobacteria Garrity et al. 2005 emend. Williams and Kelly 2013 Pseudomonadales Orla-Jensen 1921 (Approved Lists 1980) emend. Liao et al. 2020 Pseudomonadaceae Winslow et al. 1917 (Approved Lists 1980) Azotobacter Beijerinck 1901 emend. Johnstone 1974 (Approved Lists 1980) Azotobacter nigricans Krasil'nikov 1949 (Approved Lists 1980) Azotobacter nigricans achromogenes Thompson and Skerman 1981 Azotobacter nigricans Krasil'nikov 1949 (Approved Lists 1980) Azotobacter nigricans nigricans Krasil'nikov 1949 (Approved Lists 1980) Azotobacter nigricans achromogenes Thompson and Skerman 1981 List Editor Validation List no. 6. Validation of the publication of new names and new combinations previously effectively published outside the IJSB. 1981 31 2 215 218 International Journal of Systematic Bacteriology Int J Syst Bacteriol 0020-7713 10.1099/00207713-31-2-215 Note: This strain may be lost. This strain may be lost. Thompson J.P. Skerman V.B.D. Thompson J.P. Skerman V.B.D. 1979 1 405 Azotobacteraceae: The Taxonomy and Ecology of the Aerobic Nitrogen-Fixing Bacteria Academic Press London 0126890501 List Editor Validation List no. 6. Validation of the publication of new names and new combinations previously effectively published outside the IJSB. 1981 31 2 215 218 International Journal of Systematic Bacteriology Int J Syst Bacteriol 0020-7713 10.1099/00207713-31-2-215 Thompson J.P. Skerman V.B.D. Thompson J.P. Skerman V.B.D. 1979 1 405 Azotobacteraceae: The Taxonomy and Ecology of the Aerobic Nitrogen-Fixing Bacteria Academic Press London 0126890501