Adaptive laboratory evolutionary strategies and mechanisms of Synechococcus elongatu PCC 7942 under high...

To promote the utilization of industrial flue gases by microalgae, this study performed adaptive laboratory evolution (ALE) with CO₂ as the selective pressure, aiming to improve the carbon fixation efficiency of microalgae under high CO₂ conditions. Synechococcus elongatus PCC7942 was sequentially cultured with CO₂ concentrations ranging from 5 % to 20 %, resulting in a domesticated strain S20 with growth advantage and capable of acclimatizing to 20 % CO₂. At a CO₂ concentration of 20 %, the biomass of S20 reached 1.37 g L^-1, and the lipid contents of S20 were significantly elevated, reaching 54.35 % and 32.76 %, respectively. Mechanism analysis showed that the enhanced photosynthesis caused by the increase in chlorophyll a content was the main factor for S20 to tolerate high CO₂ concentration and improve carbon sequestration efficiency. Overall, this study demonstrated that CO₂ ALE is an optimal method to screen efficient carbon sequestering microalgae under high concentrations of CO₂.