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 co mposition and toxicity of the freshwater cyanobacterium Microcystis ae ruginosa were evaluated. Four media (MA, CB, A(3)M(7) and BG-11) influ enced growth in terms of cell numbers, chlorophyll a content and speci fic growth rate. MA medium supported the best growth. The macromolecul ar composition of cultured cells, viz total protein, carbohydrates, li pids, DNA and RNA content, varied reaching a maximum at various growth periods. The differences were significant due to the interaction of t he culture medium and duration. Toxicity was compared in terms of mous e units. The toxicity of cultured cells increased with the duration un til week 4 and toxicity was highest in cells grown in MA medium.