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Calcium Requirements of Azotobacter

Naturevolume 180pages14931494 (1957) | Download Citation



ALTHOUGH there have been a number of observations on the calcium requirements of individual species of Azotobacter they have concerned, almost exclusively, A. vinelandii and A. chroococcum 1,2. It has been generally agreed that calcium is essential for the growth of Azotobacter with free nitrogen but some controversy exists regarding its necessity for growth on combined nitrogen. Several authors have claimed that it is not needed for growth on nitrate or ammonia2 but others3 have failed to confirm this. Burk and his co-workers4 found it to be unnecessary in the presence of combined nitrogen, but later5 reversed this opinion, stating that equal amounts of calcium were required for growth in the presence and in the absence of fixed nitrogen.

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  1. 1

    Krzemieniewska, H., Bull. Internat. Acad. Sci. Cracovie, Cl. sci. math. nat., B, 376 (1910).

  2. 2

    Schröder, M., Zent. Bakt. Parasitenk., Abt. 2, 85, 177 (1932). Esposito, R. G., and Wilson, P. W., Proc. Soc. Exp. Biol. Med., 93, 564 (1956).

  3. 3

    Bortels, H., Zent. Bakt. Parasit., Abt. 2, 95, 193 (1936).

  4. 4

    Homer, C. K., and Burk, D., J. Agric. Res., 48, 981 (1934).

  5. 5

    Burk, D., and Horner, C. K., Proc. Third Intern. Congr. Microbiol., New York, p. 489 (1940).

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    • J. R. NORRIS

    Present address: Department of Science Bacteriology, University of Glasgow, Anderson College, 56 Dumbarton Road, Glasgow, W.1.


  1. State Laboratory for Soil and Crop Research, Lyngby, Denmark

    • J. R. NORRIS
    •  & H. L. JENSEN


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