Metabolic Engineering of for Enhanced Production of Naringenin-Derived Flavonoids: Apigenin and Acacetin.

Apigenin and acacetin are flavonoids with potent antioxidant, anti-inflammatory, and anticancer activities, making them attractive for pharmaceutical and nutraceutical applications. However, their low natural abundance presents a challenge to large-scale production. In this study, we engineered for the biosynthesis of apigenin and acacetin from naringenin. To enhance naringenin production from l-tyrosine, we introduced four heterologous genes, optimized the flux through the l-tyrosine pathway, and eliminated the competing homogentisate pathway. Malonyl-CoA availability was increased by downregulating (fatty acid synthase 1), while erythrose-4-phosphate levels were elevated through overexpression of (transketolase 1). Additionally, genes encoding flavone synthase and flavonoid 4'-O-methyltransferase were integrated to convert naringenin into apigenin, and subsequently apigenin into acacetin. Under fed-batch fermentation with an optimized carbon-to-nitrogen ratio, acacetin production reached 1.10 g/L─the highest titer reported to date in a microbial system. These results highlight as a promising chassis for scalable flavonoid biosynthesis.