1887

Abstract

SUMMARY: Nitrogenase activity of suspensions of the unicellular cyanobacterium sp. PCC 6909 plotted against the concentration of dissolved O (dO) resulted in a bell-shaped curve, both in the light and in the dark, with optima of 25 or 80 μ-O depending on the age of the culture. At the optimum dO, nitrogenase activity [typically 4 to 6 nmol CH (mg protein) min] was similar in the light or in the dark. Alteration of light intensity from zero to 2 klx, or addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), had no effect on nitrogenase activity. At 1 klx the ADP/ATP ratio was 0∙2 and showed only a marginal increase as the dO was increased. However, a high level of illumination (30 klx) stimulated or inhibited nitrogenase activity, depending on the external dO, presumably as a consequence of changes in the intracellular O concentration; in the presence of DCMU, activity increased twofold, independent of dO.

In the dark, the dependence of the rate of respiration on O concentration suggested the presence of three O-uptake systems with apparent values of 1 μ, 5 μ and 25 μ. The ADP/ATP ratio under anaerobic conditions was 0∙47 and showed a marked decrease as dO was increased to 25 μ. A CN-insensitive respiratory activity, which neither supported nitrogenase activity nor was coupled to ATP synthesis, was associated with the system with the apparent of 5 μ. The dependence of the specific activity of nitrogenase on dO indicated that both the high affinity ( 1 μ) and low affinity ( 25 μ) O-uptake systems contributed ATP or reductant for N-fixation. KCN (2∙5 m) completely inhibited nitrogenase activity in the dark and at moderate levels of illumination and dO. We conclude that respiration is the major source of reductant and ATP for nitrogenase activity both in the dark and in the light, but that photosystem I can contribute ATP at very high levels of illumination.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-132-3-789
1986-03-01
2021-10-20
Loading full text...

Full text loading...

/deliver/fulltext/micro/132/3/mic-132-3-789.html?itemId=/content/journal/micro/10.1099/00221287-132-3-789&mimeType=html&fmt=ahah

References

  1. CORNISH-BOWDEN A. 1979; Fundamentals of Enzyme Kinetics. London: Butterworth.
    [Google Scholar]
  2. Gallon J. R. 1980; Nitrogen fixation by photoautotrophs. In Nitrogen Fixation, pp. 197–238 Edited by W. D. P. Stewart & J. R. Gallon. London: Academic Press.
    [Google Scholar]
  3. Gallon J. R., Hamadi A. F. 1984; Studies on the effects of oxygen on acetylene reduction (nitrogen fixation) in Gloeothece sp. ATCC 27152. Journal of General Microbiology 130:495–503
    [Google Scholar]
  4. Gallon J. R., Larue T. A., Kurz W. G. W. 1974; Photosynthesis and nitrogenase activity in the blue-green alga Gloeocapsa. Canadian Journal of Microbiology 20:1633–1637
    [Google Scholar]
  5. Gallon J. R., Ul-Haque M. I., Chaplin A. E. 1978; Fluoroacetate metabolism in Gloeocapsa sp. LB795 and its relationship to acetylene reduction (nitrogen fixation). Journal of General Microbiology 106:329–336
    [Google Scholar]
  6. Haaker H., de Kok A., Veeger C. 1974; Regulation of dinitrogen fixation in intact Azoto-bacter vinelandii. Biochimica et biophvsica acta 357:344–357
    [Google Scholar]
  7. Hochman A., Burris R. H. 1981; Effect of oxygen on acetylene reduction by photosynthetic bacteria. Journal of Bacteriology 147:492–499
    [Google Scholar]
  8. Jensen B. B., Cox R. P. 1983; Effect of oxygen concentrations on dark nitrogen fixation and respiration in cyanobacteria. Archives of Microbiology 135:287–292
    [Google Scholar]
  9. Kallas T., Rippka R., Coursin T., Rebiere M.-C., de Marsac N. T., Cohen-Bazire G. 1983; Aerobic nitrogen fixation by nonheterocystous cyanobacteria. In Photosynthetic Prokaryotes, pp. 281–302 Edited by G. C. Papageorgiou & L. Packer. Amsterdam: Elsevier.
    [Google Scholar]
  10. Klugkist J., Haaker H. 1984; Inhibition of nitrogenase activity by ammonium chloride in Azotobacter vinelandii. Journal of Bacteriology 157:148–151
    [Google Scholar]
  11. Mullineaux P. M., Chaplin A. E., Gallon J. R. 1980; Effects of a light to dark transition on carbon reserves, nitrogen fixation and ATP concentrations in cultures of Gloeocapsa (Gloeothece) sp. 1430/3. Journal of General Microbiology 120:227–232
    [Google Scholar]
  12. Mullineaux P. M., Gallon J. R., Chaplin A. E. 1981; Acetylene reduction (nitrogen fixation) by cyanobacteria grown under alternating light-dark cycles. FEMS Microbiology Letters 10:245–247
    [Google Scholar]
  13. Murry M. A., Fontaine M. S., Tjepkema J. D. 1984; Oxygen protection of nitrogenase in Frankia sp. HFPArI3. Archives of Microbiology 139:162–166
    [Google Scholar]
  14. Pearson H. W., Howsley R. 1980; Concomitant photoautotrophic growth and nitrogenase activity by cyanobacterium Plectonema boryanum in continuous culture. Nature, London 288:263–265
    [Google Scholar]
  15. Post E., Kleiner D., Oelze J. 1983; Whole cell respiration and nitrogenase activities in Azotobacter vinelandii growing in oxygen controlled continuous culture. Archives of Microbiology 134:68–72
    [Google Scholar]
  16. Robson R. L., Postgate J. R. 1980; Oxygen and hydrogen in biological nitrogen fixation. Annual Review of Microbiology 34:183–207
    [Google Scholar]
  17. Stewart W. D. P. 1980; Some aspects of structure and function in N2-fixing cyanobacteria. Annual Review of Microbiology 34:497–536
    [Google Scholar]
  18. Whitton B. A., Sinclair C. 1975; Ecology of blue-green algae. Science Progress 62:429–446
    [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-132-3-789
Loading
/content/journal/micro/10.1099/00221287-132-3-789
Loading

Data & Media loading...

Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error