Micronutrient Requirements for Growth and Hydrocarbon Production in the Oil Producing Green Alga

The requirements of micronutrients for biomass and hydrocarbon production in Botryococcus braunii UTEX 572 were studied using response surface methodology. The concentrations of four micronutrients (iron, manganese, molybdenum, and nickel) were manipulated to achieve the best performance of B. braunii in laboratory conditions. The responses of algal biomass and hydrocarbon to the concentration variations of the four micronutrients were estimated by a second order quadratic regression model. Genetic algorithm calculations showed that the optimal level of micronutrients for algal biomass were 0.266 mM iron, 0.707 mMmanganese, 0.624 mM molybdenum and 3.38 mM nickel. The maximum hydrocarbon content could be achieved when the culture media contained 10.43 mM iron, 6.53 mM manganese, 0.012 mM molybdenum and 1.73 mM nickel. The validation through an independent test in a photobioreactor suggests that the modified media with optimised concentrations of trace elements can increase algal biomass by 34.5 % and hydrocarbon by 27.4%. This study indicates that micronutrients play significant roles in regulating algal growth and hydrocarbon production, and th