Box–Behnken modeling of biodiesel production from Botryococcus braunii microalgae

Abstract

This research aimed to model and optimize the growth factors and enhance the lipid yield from Botryococcus braunii microalgae, and to design a system for obtaining biodiesel from these lipids as this does not compromise food security. Botryococcus braunii, grown on a modified Chu-13 medium, reached the stationary phase after 27 days with a maximum cell count of 265 × 10⁴ cells mL⁻¹ after 27 days and maximum biomass yield of 725 mg L⁻¹ after 30 days on modified Chu-13 medium, which was higher than growth on Basal SAG medium. The maximum lipid content (18.47%) and lipid yield (4.46 mg L⁻¹day) were obtained when B. braunii was cultivated on modified Chu-13 medium after 30 days. Gas chromatography (GC) analysis for the lipids indicated that the highest percentages of SFAs (51.03%) and lowest percentages of monounsaturated fatty acids (MUFAs) (36.47%) and polyunsaturated fatty acids (PUFAs) (12.49%) were obtained by culturing B. braunii on modified Chu-13 medium. The effect of different growth parameters (N₂ level, NaHCO₃, and CO₂ concentrations) on growth yield was modeled by using D-optimal design response surface methodology (RSM).