Dalian Institute of Chemical Physics-CAS, China
Title: The correlation of polar lipids changes with TAG accumulation under nitrogen deprivation in Nannochloropsis oceanica based on lipidomics
Biography: Song Xue
Nannochloropsis as one of the ocean microalgal species, has been considered as a promising resource of biodiesel feedstocks because of its capacity of TAG accumulation. TAG biosynthesis has been classified in different pathways. Polar lipids have big contribution for TAG accumulation by providing acyl group or DAG. The quantification and characterization of the contribution in microalgae are still veiled. In this study, there are total 117 polar lipid species covering eight classes (i.e. MGDG, DGDG, SQDG, DGTS, PC, PE, PG, PI) identified by UPLC/Orbitrap and quantified by UPLC/Q-TOF to study the correlation of polar lipids changes with TAG synthesis under nitrogen deprivation condition of Nannochloropsis oceanica IMET1. Through comparision of the lipids profiling of polar lipids, we proposed that C18 acyl groups are desaturated while attached to PC. PE and DGTS acts as the carrier of EPA synthesis and the donors of imported DAG to the chloroplast for major MGDG which is eukaryotic-like molecule species. Under nitrogen limitation, the 16:0 acyl chain-containing lipid species in PC and DGTS were increased while 16:1 acyl chain-containing lipid species decreased. Similarly, in PE and DGTS, 18:0, 18:1 acyl chain-containing lipid species in PC and DGTS increased while 18:2 acyl chain-containing lipid species decreased. The changes of lipid species in DGTS, PC and PE further affected photosynthetic membrane lipids profiling. Thus we suggest under nitrogen limitation, the changes in polar lipid are mainly caused by the reduction of palmitic ∆7 desaturase and oleic ∆12 desaturase activity.