Archives of Microbiology

, Volume 156, Issue 5, pp 335–337

Regulation of nitrogen-fixation by different nitrogen sources in the marine non-heterocystous cyanobacterium Trichodesmium sp. NIBB1067

Authors

  • Kaori Ohki
    • Department of Cell BiologyNational Institute for Basic Biology
  • Jonathan P. Zehr
    • Marine Sciences Research CenterState University of New York
  • Paul G. Falkowski
    • Department of Applied ScienceBrookhaven National Laboratory
  • Yoshihiko Fujita
    • Department of Cell BiologyNational Institute for Basic Biology
Original Papers

DOI: 10.1007/BF00248706

Cite this article as:
Ohki, K., Zehr, J.P., Falkowski, P.G. et al. Arch. Microbiol. (1991) 156: 335. doi:10.1007/BF00248706

Abstract

The effect of various nitrogen sources on the synthesis and activity of nitrogenase was studied in the marine, non-heterocystous cyanobacterium Trichodesmium sp. NIBB1067 grown under defined culture conditions. Cells grown with N2 as the sole inorganic nitrogen source showed light-dependent nitrogenase activity (acetylene reduction). Nitrogenase activity in cells grown on N2 was not suppressed after 7 h incubation with 2 mM NaNO3 or 0.02 mM NH4Cl. However, after 3 h of exposure to 0.5 mM of urea, nitrogenase was inactivated. Cells grown in medium containing 2 mM NaNO3, 0.5 mM urea or 0.02 mM NH4Cl completely lacked the ability to reduce acetylene. Western immunoblots tested with polyclonal antisera against the Fe-protein and the Mo−Fe protein, revealed the following: (1) both the Fe-protein and the Mo−Fe protein were synthesized in cells grown with N2 as well as in cells grown with NaNO3 or low concentration of NH4Cl; (2) two bands (apparent molecular mass of 38 000 and 40 000) which cross-reacted with the antiserum to the Fe-protein, were found in nitrogen-fixing cells; (3) only one protein band, corresponding to the high molecular mass form of the Fe-protein, was found in cells grown with NaNO3 or low concentration of NH4Cl; (4) neither the Fe-protein nor the Mo−Fe protein was found in cells grown with urea; (5) the apparent molecular mass of the Fe-protein of Trichodesmium sp. NIBB1067 was about 5000 dalton higher than that of the heterocystous cyanobacterium, Anabaena cylindrica IAM-M1.

Key words

CyanobacteriumTrichodesmiumNitrogen-fixationNitrogenase

Copyright information

© Springer-Verlag 1991