Engineering of the Growth Environment of Microalgae with High Biomass and Lipid Productivity

Pure cultures of Botryococcus sp. microalgae have great potential for generating huge amounts of algae lipid that can be further converted into biodiesel. Lipids with nanometer in size can be applied to medicine and pharmacy recently. In this study, the effects of light intensity and CO₂ concentration on the biomass productivity, lipid content, and lipid productivity of Botryococcus braunii were examined in 21-day intervals. The optimum cultivating conditions for biomass accumulation were 6,000 lux with 0.04% CO₂ and 21 days of culturing; this provided the highest biomass productivity of 140.46 mg L⁻¹ d⁻¹. The highest lipid productivity of 44.46 mg L⁻¹ d⁻¹ occurred at 6,000 lux with 5% CO₂ and 21 days of culturing. The maximum specific growth rate (μ _max) was similar among different concentrations of CO₂ (0.682 d⁻¹ under 12,000 lux at 10% CO₂; 0.585 d⁻¹ under 6,000 lux at 5% CO₂). Culturing at 5% or 10% CO₂ has been shown to enhance the accumulation of lipids, introducing the possibility of using flue gas as a carbon source. The nanotechnology in this study will be helpful towards research in green science and engineering such as bio-fixation of CO₂ and drug delivery systems.