Effects of fundamental nutrient stresses on the lipid accumulation profiles in two diatom species Thalassiosira weissflogii and Chaetoceros muelleri.

Microalgae are considered as attractive feedstocks for biofuel production nowadays because of their high lipid contents and easy cultivation. In the present study, two diatoms, Thalassiosira weissflogii and Chaetoceros muelleri, were cultured under various nutrient-limitation conditions to explore their comprehensive lipid accumulation profiles for further commercialization. In T. weissflogii, the highest neutral lipid accumulation and highest lipid productivity (14.28 mg L day) were both recorded under P-limitation. In C. muelleri, the highest lipid content (35.03% of dry cell weight), highest neutral lipid accumulation, and highest lipid productivity (29.07 mg L day) were all recorded under N-limitation. Besides, the predominant fatty acids of T. weissflogii and C. muelleri were myristic acid (C14:0), palmitic acid (C16:0), and palmitoleic acid (C16:1), with the amounts of 58.4-74.4 and 74.1-87.7% of the total fatty acids, respectively. Moreover, nutrient limitations led to a lower proportion of polyunsaturated fatty acids (PUFA) than that of saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) in both species. The ratios of (SFA + MUFA) to PUFA were from 1.65 to 3.01 in T. weissflogii, and up to 3.61 to 8.59 in C. muelleri. Our results suggested the feasibility of C. muelleri as biodiesel feedstock due to its more suitable fatty acid composition and higher lipid productivity compared to T. weissflogii.