Strategies to intensify CO2 capture by microalgae for the circular bioeconomy.

In this review, we explore pathways of coupling between microscale metabolic engineering with macroscale bioprocess design to transform microalgae into intelligent carbon management platforms, focusing on strategies that enhance CO2 fixation capacity, including synthetic enhancement of carbon-concentrating mechanisms (CCMs) and metabolic reprogramming. The integration of microalgae with microbial consortia further stabilizes carbon flow and supports system resilience under environmental fluctuations. Emerging hybrid cultivation systems - powered by renewable energy and guided by artificial intelligence (AI)-based modeling - enable scalable, adaptive, and cost-effective CO2 removal. These innovations are framed within circular bioeconomy models, where microalgae convert waste carbon into bioenergy and bioproducts. Coupling of molecular, ecological, and engineering advances can overcome current deployment barriers. We propose new directions for future research that prioritize feasibility, sustainability, and multifunctionality.