Strategies for carbon regulation to enhance the efficient enrichment of energy storage materials in Tribonema minus

Tribonema minus efficiently accumulates energy storage substances such as lipids and polysaccharides, demonstrating potential for bioenergy and high-value-added product development. Carbon source regulation is a key strategy to promote energy storage compound enrichment. This study evaluated how different amounts of glycerol and glucose affected the carbon dioxide, lipid composition, photosynthesis rate, and metabolic pathways of Tribonema minus . The results showed that as glycerol and glucose concentrations increased, the biomass and lipid yield of each treatment group increased linearly, Among them, 0.4 g L ^− 1 glycerol treatment markedly raised the lipid content (48.1%) and biomass (1.81 g L ^− 1 ), while 0.5 g L ^− 1 glucose treatment showed a more significant promoting effect, and increased biomass 3.06-fold and lipid content 1.27-fold ver. control. In addition, glycerol and glucose significantly increased the protein content of microalgae, with 0.4 g L ^− 1 glycerol yielding the highest protein content (900.91 mg L ^− 1 ). Although photosynthetic efficiency decreased in the late culture stage of each treatment group, the photochemical efficiency (Fv/Fm) remained above 0.6 at all times. Non-targeted metabolomics analysis showed that the addition of 0.4 g L ^− 1 glycerol and 0.5 g L ^− 1 glucose significantly promoted fatty acid synthesis by enhancing glycolysis and providing sufficient glycerol-3-phosphate precursors, emphasizing the positive role of these carbon sources in lipid accumulation. The results indicate that glycerol and glucose serve as excellent carbon sources for T. minus culture, facilitating a cost-efficient method to enhance biomass and lipid yields for biofuel production.