Effect of temperature and nitrogen concentration on the growth and lipid content of Spirulina platensis and biodiesel production

In this study, Spirulina platensis (Cyanophyceae) was cultured at five mediums with different amounts of sodium nitrate and three different temperatures. The study was conducted at 1600 lx light intensity and a pH value of 9. The influences of nitrate amounts and temperature on biomass growth and lipid amount were studied during 20 days. The best biomass growth (1.039 ± 0.668 g L−1 dry weight and 0.780 ± 0.501 optical density) for S. platensis was obtained from the group with the temperature value of 35 °C and 2.5 g L−1 of sodium nitrate. The highest lipid production (4.70 ± 0.067% dry weight) was in the nitrate-free medium at 15 °C. The best results for biomass growth and lipid production were obtained from the group at 35 °C and 1.25 g L−1 of sodium nitrate (P < 0.05). At the end of the study, it was determined that algal biomass increased with increasing the nitrate amount but the produced lipid by the algae decreased. Intensive production was performed in accordance with the culture conditions of the most productive groups and biodiesel was obtained from the algae. The density, viscosity, and flash point of the biodiesel were calculated as 0.78, 4.67, and 107 °C, respectively.