Transcriptomic insights into dynamically optimized batch feeding strategies for carbon fixation mechanisms in CO2 absorption-microalgae conversion system.

Efficient operation of CO2 absorption-microalgae conversion (CAMC) systems relies on matching nutrient supply with cellular demand. Among the different batch feeding strategies, group 1-2 with a small amount in the adaptation period, a large amount in the growth period, and a small amount in the stable period performed best. Compared to direct addition, biomass concentration, HCO3- utilization efficiency and carbon fixation capability increased by 9.8%, 30.6% and 12.0% respectively. Meanwhile, the yields of chlorophyll, carotenoids and carbohydrates increased by 27.5%, 10.1% and 31.3%, respectively. In addition, transcriptomic analysis was employed to elucidate the mechanisms underlying the enhanced growth and metabolism of microalgae. The results indicated that batch feeding up-regulated gene expression in pathways related to ribosome, carbohydrate synthesis, TCA cycle and photosynthesis, thereby promoting more energy flow toward the accumulation of carbon fixation, carbohydrates and proteins.