Azotobacter nigricans nigricans Krasil'nikov 1949 (Approved Lists 1980) 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 nigricans Krasil'nikov 1949 (Approved Lists 1980) Azotobacter nigricans Krasil'nikov 1949 (Approved Lists 1980) Azotobacter nigricans achromogenes Thompson and Skerman 1981 Azotobacter nigricans nigricans Krasil'nikov 1949 (Approved Lists 1980) Azotobacter nigricans Krasil'nikov 1949 (Approved Lists 1980) Kennedy C. Rudnick P. MacDonald M.L. Melton T. Garrity G.M. Brenner D.J. Krieg N.R. Staley J.T. Genus III. Azotobacter Beijerinck 1901, 567AL 2005 2, Part B 2 384 402 Bergey's Manual of Systematic Bacteriology Springer New York 0387241442 Skerman V.B.D. McGowan V. Sneath P.H.A. Approved Lists of Bacterial Names 1980 30 1 225 420 International Journal of Systematic Bacteriology Int J Syst Bacteriol 0020-7713 10.1099/00207713-30-1-225 Krasil'nikov N.A. English 1949 1 830 Guide to the Bacteria and Actinomycetes Ac. Sci. USSR Publ. Moscow