Effect of culture age and pH of the culture medium on the composition of the toxin of the cyanobacterium Microcystis aeruginosa(UV-006)

Axenic cells of Microcystis aeruginosa,originally collected from the Hartbeespoort Dam, South Africa, were cultured under controlled laboratory conditions. It was shown that culture age and pH (CO2concentration) did influence the relative peptide composition of the toxin. The amino acid composition of the major constituent toxic peptides, as determined by GLC, remained unchanged. Changes in toxicity thus are related to concentration and probably are not due to structural changes of the toxic peptides.