Effects of Nitrogen Source on the Lipid Accumulation in Phaeodactylum Tricornutum

Nitrogen source has an important influence on the growth and lipid synthesis of Phaeodactylum tricornutum. It affects lipid accumulation through global metabolic regulation. However, little research has been done on the correlation between other metabolites and lipid metabolism during the synthesis of Phaeodactylum tricornutum. In this study, we studied the effect of different nitrogen sources on lipid and other major metabolic pathways in Phaeodactylum tricornutum. We not only optimized the nutritional condition, but also revealed the competitive pathway affecting the lipid synthesis in Phaeodactylum tricornutum. The results showed that urea had the most significant effect on the growth and lipid accumulation of Phaeodactylum tricornutum. The highest lipid content could be obtained in the Modified Basal Medium (MBM) with a ratio of glycine 0.7 g/L, yeast extract 5 g/L, urea 0.6 g/L, glucose 20 g/L and the total lipid yield of the optimized group was 202, 118.9, 129.4 and 53.3% higher than the basic medium group from day 2-8. Through the analysis of metabolites, it was found that protein synthesis during the growth of Phaeodactylum tricornutum was the main competitive pathway affecting its biomass and lipid accumulation. This laid a theoretical and practical foundation for the regulation of lipid accumulation in Phaeodactylum tricornutum in the future.