From Rags to Riches: Exploiting the Calvin-Benson-Bassham Cycle for Biomanufacturing

Industrial chemical production largely relies on fossil fuels, resulting in the unavoidable release of carbon dioxide (CO2) into the atmosphere. The concept of a circular carbon bioeconomy has been proposed to address this issue, wherein CO2 is captured and used as a raw material for manufacturing new chemicals. Microbial cell factories and, in particular, autotrophic microorganisms capable of utilizing CO2 as the sole carbon source, emerged as potential catalysts for upcycling CO2 to valuable products. The Calvin-Benson-Bassham cycle (CBBc), the best-known CO2 fixation pathway, is widely distributed in Nature. While extensively studied, microbial engineering programmes based on the CBBc remains relatively underexplored. In this review, we discuss avenues towards biotechnological exploitation of the CBBc to engineer CO2-utilizing microbial cell factories, with a focus on chemically-derived electron donors. We also highlight the advantages and challenges of implementing the CBBc in heterotrophic microbial hosts and its potential to advance a true circular carbon bioeconomy. Moreover, based on the pathway's architecture, we argue about the ideal value-added products to generate from this metabolic route. Altogether, studying and engineering the CBBc in both natural- and synthetic-autotrophs will enhance our understanding on this CO2 fixation pathway, enabling further exploration of biomanufacturing avenues with CO2 as feedstock. The Calvin-Benson-Bassham cycle (CBBc) is widely distributed in nature, but its potential for biomanufacturing is still underexplored. The review highlights opportunities and challenges of exploiting the CBBc for upcycling CO2 to value-added products using natural or synthetic chemoautotrophic microbial cell factories as catalysts.image

Automated summary

This review discusses the opportunities and challenges of using the Calvin-Benson-Bassham cycle (CBBc) to engineer microbial cell factories for the utilization of CO2, highlighting its potential to advance a circular carbon bioeconomy. By studying and engineering the CBBc, further exploration of biomanufacturing using CO2 as a feedstock can be achieved.