ASPECTS OF GROWTH AND NITROGENASE ACTIVITY OF THE PHOTOSYNTHETIC CYANOBACTERIUM NOSTOC-MUSCORUM IN CONTINUOUS-CULTURE

The level of photosynthetic oxygen evolution, chlorophyll, protein, ni trogenase and nitrate reductase activities were studied in the cyanoba cterium Nostoc muscorum growing in continuous culture under various ni trogen sources (N-2-free medium, NO3- or NH4+-media). The growth and p roduction rate of N. muscorum were optimal in the presence of NO3- rat her than in, the presence of NH4+ or molecular N-2. The rate of photos ynthetic O-2 evolution showed correlation with the increased chlorophy ll and protein level in NO3--grown cultures. The level of the key enzy me of nitrogen metabolism in cyanobacteria (evaluated by nitrogenase a nd nitrate reductase activities) were maxima in NO3- cultures, while N H4+-grown cultures had the lowest level.