Cyanobacteria nitrogen

In cyanobacteria nitrogen fixation occurs in the heterocysts, specialized cells with thickened cell envelopes. They supply NH4+ to other cells in the filament of which they are a part. 

In this sen.se, in natural environments, the plant needs can be fulfilled by less strict, but more homogeneously extended plant-microbe interactions, such as those that cereals undertake with free nitrogen fixers (e.g., azospirilli or cyanobacteria), and that often involve not only nitrogen exchange but also hormones and other signals. 

Fig. 6.10 Cyanobacteria in a chain of photosynthesising cells, A, which produce oxygen from light and water, with a heterocyst cell B which is anaerobic and fixes nitrogen gas.

Cyanobacteria may possess several enzymes directly involved in H2 metabolism nitrogenase(s) catalyzing the production of H2 concomitantly with the reduction of nitrogen to ammonia, an uptake hydrogenase, catalyzing the consumption of H2 produced by the nitrogenase, and a bidirectional hydrogenase, which has the capacity to both take up and produce H2 [3, 5],... 

Cyanoacetic acid, 2 138, 139 and esters, 2 7 244-245 Cyanoacrylate adhesives, 2 539-540 Cyanoacrylate vapors, 22 102 Cyanobacteria, in nitrogen fixation, 2 7 302 Cyanobacterial associations, in nitrogen fixation, 27 299-300 Cyanocobalamin, 7 238 25 803-804 Cyanoethene. See Acrylonitrile (AN) l-Cyanoethyl-2-ethyl-4-methylimidazole (2EMZ-CN) curing catalyst, 20 17 2V-Cyanoethylated toluenediamines, 25 197... 

Marino R, Howarth RW, Chan F, Cole JJ, Likens GE (2003) Sulfate inhibition of molybdenum-dependent nitrogen fixation by planktonic cyanobacteria under seawater conditions a non-reversible effect. Hydrobiol 500 277-293... 

When filamentous cyanobacteria such as Nostoc or Anabaena are grown under limited combined N2, 5-10 per cent of their vegetative cells differentiate to form heterocysts. Heterocyst formation does not take place randomly within the filament. Most probably it is a dynamic selection in response to nitrogen deprivation but neither the existence of predetermination nor a combination of both events can be ruled out (Wolk 1996). 

Bothe, H., Kentemich, T. and Heping, D. (1991) Recent aspects on the hydrogenase-nitroge-nase relationship in cyanobacteria. In M. Polsinelli, R. Materassi and M. Vincenzini (eds). Nitrogen Fixation. Dordrecht Kluwer Academic Publishers, pp. 367-75. 

Haselkorn, R. and Buikema, W. J. (1992) Nitrogen fixation in cyanobacteria. In G. Stacey, R. H. Burris and H. J. Evans (eds). Biological Nitrogen Fixation. London, Great Britain Chapman and Hall, pp. 166-90. 

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