Enhancing CO fixation by microalgae in a Photobioreactor: Molecular mechanisms with exogenous carbonic anhydrase.

Microalgae biotechnology holds great potential for mitigating CO emissions, yet faces challenges in commercialization due to suboptimal photosynthetic efficiency. This study presents an innovative approach to improve CO mass transfer efficiency in microalgae using carbonic anhydrase (CA) in an internal LED flexible air-lift photobioreactor. Optimal conditions initial inoculation with 3.55 × 10 cells/mL and 20 % CO concentration, complemented by white LED lighting in Chlorella sp. CA regulated intracellular composition, enhancing chlorophyll, lipid, and protein contents. Metabolomics revealed elevated malic and succinic acids, associated with increased Ribulose 1,5-bisphosphate carboxylase oxygenase (RuBisCO) and Acetoacetyl coenzyme A (Acetyl-CoA) activities, facilitating efficient carbon fixation. CA also mitigated cellular oxidative stress by reducing reactive oxygen species (ROS). Furthermore, CA improved extracellular electron acceptor with currents surpassed CK. This CA-based microalgae biotechnology provides a foundation for future commercial applications, addressing CO emissions.