Novel Media for Lipid Production of Chlorococcum oleofaciens : A RSM Approach

Abstract

The algal medium was optimized to increase the biomass and lipid production of Chlorococcum oleofaciens. The significant variables were screened and chosen from previously reported algal culture media using Plackett Burman Design (PBD). Optimization of the significant variables were performed using central composite design. The Pareto chart for PBD revealed that the salts such as sodium bicarbonate, sodium nitrate, potassium nitrate and ferrous sulphate had enhanced the biomass and lipid production. The variables and its effect on the responses were further studied by central composite design (CCD). A new medium was formulated based on the response surface methodology. The predicted concentration of NaHCO3, NaNO3, KNO3, MgSO4.7H2O were found to be 6.75 g/L, 0.75 g/L, 1.88 g/L and 0.35 g/L respectively. The actual and the predicted total lipid yield for the optimized media was around 0.74 g/L and 0.78 g/L respectively. The optimal medium has been named as AM medium. Growth and the lipid yields of C. oleofaciens were found higher in AM medium. The specific growth rates of C. oleofaciens in AM and CFTRI media were found to be 0.14 day-1 and 0.19 day-1 respectively. The biomass produced by the optimized AM medium was found to be 2.7 times greater compared to the CFTRI medium. The lipid was extracted and GC-MS was performed which revealed that the fatty acids were predominantly of the class C15:0, C18:0, C16:0 and C12:0. It is concluded that besides lipid content, AM medium increased the cell number leading to the increase in biomass.