Recent Advances in Engineering Heterotrophic Microorganisms for Reinforcing CO₂ Fixation Based on Calvin-Benson-Bassham Cycle

Global climate change caused by greenhouse gas emission is the fundamental challenge facing mankind. Biological carbon dioxide fixation has recently attracted much attention. The Calvin-Benson-Bassham (CBB) cycle is a major carbon fixation pathway in the biosphere, and it is the most intensively studied because of its prominence and key role in nature as the primary pathway for net CO₂ fixation. It was recently shown that expressing the enzymes ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and phosphoribulokinase (PRK) in Escherichia coli, Saccharomyces cerevisiae, Methylobacterium extorquens, Kluyveromyces marxianus, and Pichia pastoris could achieve CO₂ fixation for the production of value-added chemicals. In addition, expressing the synthetic CBB cycle allowed strains to grow autotrophically on CO₂. Here, we review the current understanding of the CBB cycle for CO₂ fixation, summarize research progress in the assembly of the CBB cycle in heterotrophic microorganisms or developing synthetic autotrophs, and present the strategies to enhance carbon fixation efficiency of the CBB cycle in heterotrophic microorganisms. Recent progress in such applications in reinforcing CO₂ fixation for the improved production of various value-added chemicals is also summarized. The challenges encountered in this process and future prospects are further discussed.