摘要：Photosynthetic terpene production represents one of the most carbon and energy-efficient routes for converting CO_(2)into *** photosynthetic organisms,metabolic engineering has led to limited success in enhancing terpene productivity,partially due to the low carbon *** this study,we employed systems biology analysis to reveal the strong competition for carbon substrates between primary metabolism(e.g.,sucrose,glycogen,and protein synthesis)and terpene biosynthesis in synechococcus elongatus PCC *** then engineered key“source”and“sink”***“source”limitation was overcome by knocking out either sucrose or glycogen biosynthesis to significantly enhance limonene production via altered carbon ***,a fusion enzyme complex with geranyl diphosphate synthase(GPPs)and limonene synthase(Ls)was designed to further improve pathway kinetics and substrate *** synergy between“source”and“sink”achieved a limonene titer of 21.0 mg/***,the study demonstrates that balancing carbon flux between primary and secondary metabolism can be an effective approach to enhance terpene bioproduction in *** design of“source”and“sink”synergy has significant potential in improving natural product yield in photosynthetic species.