Leveraging the dynamics of microalgal <scp>CO₂</scp> capture to estimate the maximum inherent photosynthetic potential

Abstract BACKGROUND Natural photosynthesis, utilizing intelligent molecular machinery to harness sunlight, stands as the benchmark for efficient energy generation. Despite its high quantum efficiency compared to synthetic methods, challenges persist due to dynamic nutritional and light requirements in plant, microalgae, and cyanobacteria‐driven processes. Reported microalgae CO 2 uptake rates rely on biomass dry cell weight measurement after certain incubation period and systematic study of required CO 2 concentrations for optimal photobioreactor operation remaining unexplored. This research is thus aimed at evaluating the critical dissolved CO 2 (C crit ∙ CO 2 ) concentration and specific CO 2 uptake rates (SCUR) of Chlorella minutissima (CM) culture in the presence of surplus light and other nutrients by online monitoring and measuring the dynamic CO 2 uptake rates which will help in maintaining the optimal rate of CO 2 delivery for continuous cultivation of microalgae while minimizing the escape of CO 2 . RESULTS Dissolved C crit ∙ CO 2 was determined to be in the range of 16–20 mg/L, and the maximum SCUR in BBM (Bold Basal Medium) was found to be 0.73 mg CO 2 (mg dcw ∙ h) −1 . Interestingly, this SCUR value is nearly three times greater than that of the most efficient in vitro artificial photosynthetic novel pathway reported so far. CONCLUSION From the calculated SCUR values, it may be noted that 9.6 g of biomass can be obtained from 1 g of microalgal inoculum in a day, thereby setting a benchmark for the scientists working in the areas of bioprocess engineering, synthetic biology, and metabolic engineering to comply. © 2024 Society of Chemical Industry (SCI).