Engineering of a modular and synthetic phosphoketolase pathway for photosynthetic production of acetone from CO 2 in S ynechococcus elongatus PCC 7942 under light and aerobic condition

Summary Capture and conversion of CO 2 to valuable chemicals is intended to answer global challenges on environmental issues, climate change and energy security. Engineered cyanobacteria have been enabled to produce industry‐relevant chemicals from CO 2 . However, the final products from cyanobacteria have often been mixed with fermented metabolites during dark fermentation. In this study, our engineering of S ynechococcus elongatus PCC 7942 enabled continuous conversion of CO 2 to volatile acetone as sole product. This process occurred during lighted, aerobic culture via both ATP ‐driven malonyl‐ C o A synthesis pathway and heterologous phosphoketolase ( PHK )‐phosphotransacetylase ( P ta) pathway. Because of strong correlations between the metabolic pathways of acetate and acetone, supplying the acetyl‐ C o A directly from CO 2 in the engineered strain, led to sole production of acetone (22.48 mg/L ± 1.00) without changing nutritional constraints, and without an anaerobic shift. Our engineered S . elongatus strains, designed for acetone production, could be modified to create biosolar cell factories for sustainable photosynthetic production of acetyl‐ C o A ‐derived biochemicals.