Carbon Capture and Utilization Through Microalgae and Carbonic Anhydrases: Opportunities, Challenges and Future Directions

The continuous increase in carbon dioxide (CO2) has intensified the need for sustainable technologies to mitigate greenhouse gas emissions. Carbon Capture and Utilization (CCU) represents a promising strategy to convert captured CO2 into valuable products, contributing to climate change mitigation and the circular economy. This review provides an overview of the main carbon management pathways, including Carbon Capture and Storage (CCS), Carbon Capture, Utilization and Storage (CCUS), and CCU, with a focus on biological CCU (bio-CCU) based on microalgae and carbonic anhydrases (CAs). Particular attention is given to the role of CAs as highly efficient biocatalysts that accelerate CO2 hydration, enhancing inorganic carbon availability. Recent advances in enzyme immobilization technologies and support materials are examined, highlighting their potential to improve enzyme stability, reusability, and process performance. Furthermore, the integration of immobilized CAs with microalgal cultivation systems is explored as an emerging strategy in which CAs facilitate inorganic carbon availability and delivery, potentially enhancing its photosynthetic fixation by microalgae and biomass productivity. Building on previous studies on microalgal bio-CCU and CA-assisted carbon capture, this review provides an integrated perspective on CA immobilization strategies, support materials, and their potential implementation in microalgal bio-CCU systems, highlighting how enzyme immobilization can connect enzymatic CO2 conversion with microalgal carbon fixation and contribute to sustainable CO2 valorization and environmental remediation.