Biological conversion of CO₂ for bioproduction: beyond natural limitations

Natural biological CO₂ fixation converts atmospheric CO₂ to energy-dense carbohydrates, thereby providing an alternative to fossil fuels and contributing to the restoration of carbon balance. Recent advancements in the mechanisms of biological CO₂ fixation have led to innovative architectures of CO₂ fixation pathways and energy systems that exceed the efficiency of natural carbon assimilation. Synthetic CO₂ bioconversion systems (SCBS) have been designed and reprogrammed for the carbon-neutral or carbon-negative biomanufacturing of chemicals from CO₂ by integrating multi-carbon biosynthesis with various energy conversion methods, including light, electrical, and chemical processes. In this review, we systematically analyze how to achieve efficient matching of CO₂ fixation modules with energy supply modules, aiming to establish scalable SCBS for addressing the pressing issue of atmospheric CO₂ overload. Then, we propose a systematic framework for designing next-generation biomanufacturing with enzymatic or microbial CO₂ bioconversion systems, facilitating the construction and optimization of SCBS towards carbon-neutral or carbon-negative bioproduction. Furthermore, we emphasize transformative SCBS technologies, such as photo-biohybrid systems for converting light into chemical energy, electro-biohybrid systems for transducing electrical energy into chemical forms, and enzyme cascade systems for repurposing chemical energy, all of which aim to achieve unprecedented efficiency in powering biosynthesis from CO₂. Finally, we propose a strategic roadmap for carbon-negative biomanufacturing ecosystems, wherein bioinspired CO₂ fixation platforms can synergistically integrate with the principles of a circular economy to facilitate the industrial transition to net-zero emissions.