Abstract:
Microalgae are considered feedstock for biodiesel production due to their capability to accumulate triacylglycerols, which
have a 99% conversion rate into biodiesel, under certain conditions. This study aims to evaluate thirty native microalgal
strains as feedstock for biodiesel production based on their biomass and lipid productivities, and total lipid and triacylglycerol
contents under nitrogen-sufcient and nitrogen starvation conditions. In addition, Chlamydomonas reinhardtii cw15 mutant
strain was utilized as a reference strain for triacylglycerol accumulation. Among the eight potent strains, Chlorella vulgaris
KP2 was considered as a most promising strain with the highest triacylglycerol content, highest total lipid content (28.56%
of dry cell weight), and the highest lipid productivity (4.56 mg/L/day) under nitrogen starvation. Under nitrogen starvation,
the major fatty acids in the triacylglycerol of Chlorella vulgaris KP2 were C18:1 (37.56%), C16:0 (23.16%), C18:0 (23.07),
C18:2 (7.00%), and C18:3 (3.12%), and the percentages of saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids represented 49.26, 38.73, and 10.12% of the total fatty acids, respectively. Furthermore, the fatty acid
methyl esters of triacylglycerol displayed remarkable biodiesel properties with a lower iodine value (59.00 gI2/100 g), higher
oxidative stability (14.24 h) and higher cetane number (58.73) under nitrogen starvation. This study suggests that nitrogenstarved Chlorella vulgaris KP2 could be used as a feedstock for biodiesel production due to the considerable amounts of
triacylglycerol and favorable biodiesel properties.