Effects of nutrient media and culture duration on growth, macromolecular composition and toxicity in batch cultures of Microcystis aeruginosa

The effects of media and culture duration on growth, macromolecular composition and toxicity of the freshwater cyanobacterium Microcystis aeruginosa were evaluated. Four media (MA, CB, A(3)M(7) and BG-11) influenced growth in terms of cell numbers, chlorophyll a content and specific growth rate. MA medium supported the best growth. The macromolecular composition of cultured cells, viz total protein, carbohydrates, lipids, DNA and RNA content, varied reaching a maximum at various growth periods. The differences were significant due to the interaction of the culture medium and duration. Toxicity was compared in terms of mouse units. The toxicity of cultured cells increased with the duration until week 4 and toxicity was highest in cells grown in MA medium.