| dc.description.abstract | Growth and toxin production of Microcytis aeruginosa PCC7806 (M. aeruginosa) grown in different Mg2+ concentrations and light intensities were investigated in this study. M. aeruginosa were cultured in four different Mg2+ concentrations (MgSO4 content: 5, 12.5, 25 and 50 mg/L) in duplicate. Two experiments at low and high light intensities (8 μEm-2s-1 and 75 μEm-2s-1, respectively) were performed for 42 and 24 days, respectively. Mg2+ concentrations in media, pH, optical density, chlorophyll a concentrations, microcystin concentrations were analysed and morphology of M. aeruginosa cells observed during the experiments. Mg2+ concentrations in media were stable during the experiments at both light intensities. Optical density and chlorophyll a concentrations of each medium showed variation in onsets of the exponential growth phase at low light intensity. The biomass parameters had stronger positive correlation at low light intensity (r> 0.974) than at high light intensity (r > 0.861). Microcystin contents reached the highest value during the exponential growth phase and the stationary phase at low and high light intensity, respectively. It is suggested that Mg2+ concentrations may affect the cell division during the lag phase at low light intensity. This study reconfirms effects of light intensity on the growth and toxin production of M. aeruginosa like past studies. | nb_NO |
