FIB-SEM combined with proteomics and modification omics clarified mechanisms of lipids synthesis in organelles of Chlorella pyrenoidosa cells with high CO2 concentration

In order to explain reasons why flue-gas CO2 (normally containing high CO2) enhanced carbon fixation and lipids syn-thesis with increased photochemical electron production in microalgae cells. Focused ion beam scanning electron mi-croscopy (FIB-SEM) was combined with proteomics and phosphorylation modification mics to clarify mechanisms of lipids synthesis at protein and organelle levels in Chlorella pyrenoidosa cells cultivated with high CO2 concentration (15 % v/v). The volumes of chloroplast and endoplasmic reticulum in subcellular organelles increased by 47 % and 306 %, respectively, compared with the control, which improved conversion efficiency of starch grains to lipids (lipid content increased by 57 %). Proteomics and modifications omics revealed that protein translation and ribosome structure and biogenesis-related enzymes were significantly modified by phosphorylation, which regulated protein bi-ological functions. Glycolysis, pentose phosphate pathway and other carbohydrate metabolic pathways were markedly enriched and promoted the expression of lipid synthase, which was consistent with enhanced carbon fixation in pho-tosynthesis, expansion of subcellular organelles and improved lipids synthesis.