High‐Level Production of Abscisic Acid by Multi‐Strategy Combination Optimization in <i>Botrytis cinerea</i>

Abscisic acid (ABA), a crucial phytohormone, is industrially synthesized using Botrytis cinerea and has wide-ranging applications in agriculture, forestry, and environmental conservation. However, the industrial fermentation of ABA using B. cinerea still faces numerous challenges. In this study, the ABA biosynthetic capacity of B. cinerea was significantly improved through a multi-strategy optimization approach, including regulating the stress defense system, enhancing cofactor supply, and optimizing fermentation conditions. First, the addition of antioxidant compounds improved the stress defense capability of B. cinerea, with retinol supplementation increasing ABA production to 1.22 g/L. Subsequently, transcriptomic and biochemical analyses revealed a significant improvement in the overall stress defense system of B. cinerea. Further enhancement of cofactor supply through in vivo metabolic engineering significantly boosted ABA accumulation. Finally, optimization of fermentation conditions increased ABA production to 1.72 g/L, marking a 76% increase compared to the initial yield. This study establishes a robust approach to enhance ABA biosynthesis in B. cinerea, offering valuable insights for advancing the cultivation efficiency of filamentous fungi in industrial bioprocessing.