Cost Effective Approach for Production of Chlorella pyrenoidosa: A RSM Based Study

Microalgae are considered as a promising feedstock for biodiesel production due to their faster growth rate, higher biomass productivity and lipid content which ranges from 20 to 50% of its dry weight. In this work, optimization of bold basal media (BBM) for the production of Chlorella pyrenoidosa are studied with central composite design (CCD) using response surface methodology. The classical optimization is used for identifying the best pH for the growth of C. pyrenoidosa and found to be 8. The screening of significant factors for the growth was studied using Plackett–Burman design (PBD) with 7 factor experiment. The significant factors identified were MgSO₄⋅7H₂O, CaCl₂⋅2H₂O, KNO₃, Na₂EDTA from PBD of experiment. These significant factors were included in a CCD, resulting in 31 experiments, that were further performed. The chlorophyll a, chlorophyll b, chlorophyll a, b and turbidity were measured regularly during experiments. The optimum concentration of MgSO₄⋅7H₂O, CaCl₂⋅2H₂O, KNO₃, and Na₂EDTA were found to be 0.1, 0.0375, 0.375, and 0.0625 g/L, respectively. The turbidity, chlorophyll a, chlorophyll b and chlorophyll a, b obtained with optimum concentrations of BBM were 0.809, 5.7504, 1.6137 and 7.3642 mg/L respectively. The results showed a yield of more than 5 times higher with optimized BBM as compared to the actual media. Moreover, the effect of light and urea on C. pyrenoidosa growth were studied and it was found that turbidity, chlorophyll a, chlorophyll b and chlorophyll a, b were maximum when an artificial light of 3500 lx was used. The nitrogen starvation during the growth of C. pyrenoidoa showed a maximum lipid content of 36.03% dry weight on 16th day which is quite sufficient for the production of biodiesel. Hence, C. pyrenoidosa could be cultivated with the optimum BBM for biodiesel production.