The effect of LEDs on the growth and fatty acid composition of Botryococcus braunii

This study investigated the effects of LEDs on biomass growth and production, lipid and fatty acid composition, and biodiesel properties as well as power efficiencies of LEDs using Botryococcus braunii. Cells were cultured using LEDs applied as: Red (R), Blue (B), 80% Red+20% Blue (80%R–20%B), 80% Blue+20% Red (80%B-20%R) and cool-white (CW) (control) under a photon flux density (PFD) of 50 ± 5 μmol m−2 s−1. R and B-LEDs yielded a lower lipid content than mixed-colored LEDs (80%R–20%B and 80%B-20%R). The microalgae had the highest lipid content of 50.13% under 80%R-20%B-LED illumination. The main fatty acid in B. braunii was oleic acid (C18:1) reaching the highest value of 52.79%. The highest power efficiency for biomass was obtained from 80%R to 20%B-LED. Multivariate statistical cluster analysis showed that 80%R-20%B-LED had a power efficiency of biomass 153.96 mg L−1 kWh−1 and a power efficiency of lipid 77.18 mg L−1 kWh−1, a cetane number of 50, an iodine value of 102 g I2 100 g−1, an unsaturation degree of 111.1% and a cold filter plugging point of −7.8 °C for energy-efficient and qualified biodiesel production.