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

Globalclimate change caused by greenhouse gas emissionis thefundamental challenge facing mankind. Biological carbon dioxide fixationhas recently attracted much attention. The Calvin-Benson-Bassham(CBB) cycle is a major carbon fixation pathway in the biosphere, andit is the most intensively studied because of its prominence and keyrole in nature as the primary pathway for net CO2 fixation.It was recently shown that expressing the enzymes ribulose-1,5-bisphosphatecarboxylase/oxygenase (RuBisCO) and phosphoribulokinase (PRK) in Escherichia coli, Saccharomyces cerevisiae, Methylobacterium extorquens, Kluyveromycesmarxianus, and Pichia pastoris could achieveCO(2) fixation for the production of value-added chemicals.In addition, expressing the synthetic CBB cycle allowed strains togrow autotrophically on CO2. Here, we review the currentunderstanding of the CBB cycle for CO2 fixation, summarizeresearch progress in the assembly of the CBB cycle in heterotrophicmicroorganisms or developing synthetic autotrophs, and present thestrategies to enhance carbon fixation efficiency of the CBB cyclein heterotrophic microorganisms. Recent progress in such applicationsin reinforcing CO2 fixation for the improved productionof various value-added chemicals is also summarized. The challengesencountered in this process and future prospects are further discussed. An engineered heterotrophic microorganismequipped withthe Calvin-Benson-Bassham cycle is a promising platformorganism for green biomanufacturing and developing to-be syntheticautotrophs.

Automated summary

Global climate change caused by greenhouse gas emission is the fundamental challenge facing mankind. Recently, biological carbon dioxide fixation has received much attention, with the Calvin-Benson-Bassham (CBB) cycle being the most studied pathway. This paper reviews the understanding of the CBB cycle, summarizes the progress in assembling the CBB cycle in heterotrophic microorganisms, and discusses the strategies to enhance carbon fixation efficiency. The potential applications of the engineered microorganisms in green biomanufacturing and synthetic autotrophs are also discussed.