Multivariate modular metabolic engineering for enhanced gibberellic acid biosynthesis in Fusarium fujikuroi

Gibberellic acid (GA₃) is one of natural phytohormones, widely used in agriculture and downstream fields. Qualified for the nature productivity, Fusarium fujikuroi was currently employed for the industrial biotransformation from agriculture residues into GA₃. Herein, Multivariate modular metabolic engineering (MMME) was assigned to reconstitute the metabolic balance in F. fujikuroi for enhancing GA₃ production. Three modules including precursor pool, cluster-specific channel and P450-mediated oxidation in GA₃ biosynthetic pathway were defined and optimized separately. The enhancement of both precursor pool and cluster-specific channel pushed metabolic flux transfer into the GA₃-specific pathway. Moreover, both introduction of Vitreoscilla hemoglobin and reinforcement of NADPH-dependent cytochrome P450 reductase facilitated oxidation cofactor transfer and subsequently boosted mycelium growth and GA₃ biosynthesis. Integration of three modules in the engineered strain accumulated 2.89 g/L GA₃ in shake flask via submerged fermentation, presenting a promising modular metabolic engineering model for efficient microbial transformation in agro-industrial application.