| M. Aeruginosa was selected as the research object in the orthogonal experiments for investigating the impact of nutrients such as nitrogen, phosphorus and Ca2+, light intensity, temperature and environmental factors on its growth and group formation. The form of M. Aeruginosa was observed by inverted fluorescent microscope, scanning electron microscope and laser confocal microscope respectively, which was used to explain the biologic reasons for its group formation from the micro perspective. Results from the orthogonal experiments showed that the group formation was affected by multiple factors like the initial concentration of N, P and Ca2+, light intensity, temperature and environmental factors, etc. In best combination, the initial concentration of N, P, Ca2+ were 100 mg/L, 5 mg/L and 260 mg/L, respectively, with the temperature 25 ℃ and light intensity 4 000 lx. On this condition, the algal cell density and EPS mass concentration reached to their maximum. Results from the morphology observation showed that microcystin algae cells could form intercellular space during their growing process, where EPS and Ca2+ played an important role. |
