Influence of photoperiod, light illumination, and pH on total lipids, triacylglycerol content, saturated and unsaturated fatty acid levels in the microalga Chlorella vulgaris for biodiesel.

The present study has examined the influence of various photoperiods, light intensities, and pH on the biomass, total lipids, triacylglycerol (TAGs), biodiesel conversion, and fatty acid composition of Chlorella vulgaris (C. vulgaris) for sustainable fuel production. Of the L/D photoperiods tested, biomass yield was low in the 10:14 h grown culture of about 0.94 g/L, while a high biomass yield of 1.486 g/L was recorded in the 16:08 h grown culture on the 20^th day. Of the 1000, 1500, 2000, and 2500 lx light irradiation tested, higher biomass production of 1.613 g/L was achieved in the 2000 lx-grown cells. However, initial pH levels of medium such as 5, 6, 7, 8, and 9 did not have an impact on the biomass yield. Regarding the lipid content, the high total lipid content of 29.85 % and 30.85 % was obtained from the culture grown at 16:08 h L/D photoperiod and 2500 lx, respectively. Concerning the TAG proportion in the total lipids, the maximal TAG of 46.83 and 44.47% (100g total lipids) were from the 16:08 h L/D cycle and 2500 lx condition, respectively. The high biodiesel yield of about 68.58 % and 65.98% was noticed from 16:08 h L/D and 2500 lx, respectively. Further, the fatty acid profile analysis of the biodiesel produced from the optimal conditions indicated that saturated fatty acids (SFAs) and polyunsaturated fatty acids (PUFAs) levels were 54.37 and 45.63% under 16:08 photoperiod, respectively, while they were 52.74 and 47.26%, respectively under 2500 lx light illumination condition. [ABSTRACT FROM AUTHOR]