Temperature effects on lipid properties of microalgae Tetraselmis subcordiformis and Nannochloropsis oculata as biofuel resources

Microalgae Tetraselmis subcordiformis and Nannochloropsis oculata were cultured at 15, 20, 25, 30, and 35°C and their properties as potential biofuel resources were examined. The results indicate that T. subcordiformis and N. oculata grew best at 20°C and 25°C and yielded the highest total lipids at 20°C and 30°C, respectively. With increased temperature, neutral lipid and polyunsaturated fatty acids (FAs) decreased while saturated FAs increased, accompanied by increased monounsaturated FAs (MUFAs) in T. subcordiformis and decreased MUFAs in N. oculata; meanwhile, the predicted cetane number of FA methyl esters increased from 45.3 to 47.6 in T. subcordiformis and from 52.3 to 60.3 in N. oculata. Therefore, optimizing culture temperatures is important for improving microalgal biodiesel production.