Formation of biomass,total protein,chlorophylls, lipids and fatty acids in green and blue-green algae during one growth phase.

Batch cultures (8–32 l.) of Chlorella vulgaris and Scenedesmus obliquus and of Anacystis nidulans and Microcystis aeruginosa were grown in media containing 0.001 % KNO₃ and at several stages in growth sampled for biomass, total protein, chlorophylls, lipids and fatty acids. With increasing time and decreasing nitrogen concentrations, the biomass of all of the algae increased, whereas the total protein and chlorophyll content dropped. Green and blue-green algae, however, behaved differently in their lipid metabolism. In the green algae the total lipid and fatty acid content as well as the composition of these compounds changed considerably during one growth phase and was dependent on the nitrogen concentration in the media at any given day of growth. More specifically, during the initial stages of growth the green algae produced larger amounts of polar lipids and polyunsaturated C₁₆ and C₁₈ fatty acids. Towards the end of growth, however, these patterns changed in that the main lipids of the green algae were neutral with mainly saturated fatty acids (mostly 18:1 and 16:0). Such changes did not occur in the blue-green algae. These differences between prokaryotic and eukaryotic algae can possibly be explained by the ‘endosymbiont theory’.