Strengthening carbon concentrating mechanisms of ambient CO2 with OLA@KAUST-7 nanoparticles for producing microalgal biomass.

In response to the mass transfer limitation of low concentration CO2 (approximately 400 ppm) in closed tubular photobioreactors aimed at improving indoor air quality, nanomaterials with excellent hydrolytic stability, OLA@KAUST-7, served as CO2 carriers. This approach sought to enhance carbon sequestration efficiency and biomass accumulation in Chlorella. The experiment examined the effects of varying addition amounts (0.01, 0.05, and 0.1 mmol/L) on the growth and physiological metabolism of Chlorella. The results indicated that 0.01 mmol/L represented the optimal dosage; at this concentration, the conversion efficiency of algal liquid CO2 to HCO3- increased by 55.7%. Transcriptomic analysis confirmed that the introduction of an appropriate amount of OLA@KAUST-7 significantly upregulated the gene expression of key proteins in the photosystem, such as Lhcb and psbO, as well as core energy metabolism enzymes like gpi and aco. This upregulation synergistically enhanced photochemical energy conversion efficiency and intracellular energy supply. The synthesis capacity of photosynthetic pigments in Chlorella significantly improved, ultimately resulting in a 53.06% increase in biomass yield.