Process optimization and modeling for the cultivation of Nannochloropsis sp. and Tetraselmis striata via response surface methodology

The aim of this study was to determine the optimal physical process conditions for the cultivation of locally isolated strains of Nannochloropsis sp. and Tetraselmis striata to achieve maximum growth rate. It was essential to evaluate biomass production at different agitation rates, light intensities, and temperature levels. Central composite design and response surface methodology were applied to design the experiments and optimize the cultivation process for Nannochloropsis sp. and T. striata. The specific growth rate of 0.250 d-1 was obtained for Nannochloropsis sp. cells under the light intensity of 54 µmol photons · m-2 · s-1, at the agitation rate of 151 rpm in 24.5°C. The optimal physical process conditions for T. striata were obtained under the light intensity of 56 µmol photons · m-2 · s-1 in 25.5°C at the agitation rate of 151 rpm in 25.5°C, resulting in a specific growth rate of 0.226 d-1. The predicted values were justified by the verification tests. Good agreement between the predicted values and the experimental values confirmed the validity of the models for the cultivation of microalgal strains. In this article, the noteworthy result was that temperature was a dominant factor in obtaining high chl-a content for Nannochloropsis sp., whereas the growth of T. striata strongly depended on light exposure. © 2015 Phycological Society of America