Abstract:By means of the common rotation composite design of quadratic regression, four mathematical models were established to analyze the impact of light intensity (x1), temperature (x2) and salinity (x3) on cell division rate (k) of each microalgal species seperated from shrimp ponds in mixed culture. The suitable conditions for the microalgae growth and the weightiness of each factor to the cell division rate were obtained. The suitable light intensity for Cryptomonas erosa ranged from 5 750 lx to 7 944 lx, the suitable temperatures ranged from 21.3 ℃ to 28.3 ℃ and the suitable salinity ranged from 13.3 to 23.0. The weightiness of the impact of each factor on cell division rate was x3>x2>x1. The suitable light intensity for Nitzschia closterium ranged from 5 761 lx to 8 697 lx, the suitable temperatures ranged from 23.4 ℃ to 29.6 ℃ and the suitable salinity ranged from 11.9 to 25.7. The weightiness of the impact of each factor on cell division rate was x3>x1>x2. The suitable light intensity for Nannochloropsis oculata ranged from 6754lx to 8775lx, the suitable temperatures ranged from 17.1 ℃ to 20.7 ℃ and the suitable salinity ranged from 19.6 to 26.4. The weightiness of the impact of each factor on cell division rate was x2>x3>x1.The suitable light intensity conditions for Chlorella pyrenoidosa ranged from 7 128 lx to 9 012 lx, the suitable temperatures ranged from 18.7 ℃ to 26.7 ℃ and the suitable salinity ranged from 17.9 to 24.3. The weightiness of the impact of each factor on cell division rate was x1>x2>x3. The k of Cryptomonas erosa and Nitzschia closterium was significantly affected by salinity acting synergistically with light intensity and temperature.
