The major changes in lipid composition of Sargassum horneri during different growth phases

Brown algae are considered as potential alternative sources of marine lipids. As one of the principal seaweeds, Sargassum horneri (Turner) C. Agardh plays an important ecological role in offshore waters in China, providing an environment for a distinctive and specialized group of marine animals and plants. However, the changes in lipid composition of S. horneri during different growth phases (from germlings to mature stages) remain largely unexplored. In the present study, we identified 8 forms of monogalactosyldiacylglycerols (MGDGs), 1 digalactosyldiacylglycerol (DGDG), 18 sulfoquinovosyldiacylglycerols (SQDGs), 1 lyso-SQDG and 15 1,2-diacylglyceryl-O-2'-(N,N,N-trimethyl)-beta-alanines (DGTAs) in S. horneri. SQDG was the most abundant lipid in S. horneri, followed by MGDG and DGTA. Our data showed that the changes in lipid composition highly depended on the algal development stage. The total contents of lipids, including MGDG, DGDG, and DGTA, were initially increased and then decreased during the growth phase of S. horneri. This finding indicated that initially the cells divided rapidly and photosynthetic membranes developed. Then, with S. horneri becoming mature, the photosynthesis efficiency and the cytomembranes started to decline. The contents of DGTA, DGDG, MGDG, and SQDG were higher in male sporophytes/receptacles than those in female sporophytes/receptacles when S. horneri reached sexual maturity.