Enhancing Precursor Supply and Engineering Efflux Systems to Improve Abscisic Acid Production and Secretion in <i>Yarrowia lipolytica</i>

Abscisic acid is a sesquiterpene phytohormone with extensive applications in agriculture and human health. Currently, it is produced through fermentation of <i>Botrytis cinerea</i>, a plant pathogenic filamentous fungus. The process requires morphology controls, which complicates production and strain optimization. In this study, the abscisic acid production strain <i>Yarrowia lipolytica</i> SM309 was optimized by enhancing the precursor supply using a "push-pull-restrain" strategy focusing on acetyl-CoA, which increased abscisic acid production from 266.34 to 328.51 mg/L. Subsequently, <i>in silico</i> prediction and analysis were used to obtain the docking conformations and binding affinity of ABC transporters for abscisic acid. Overexpression of ABC transporter <i>Yl</i>Gcn20 further enhanced abscisic acid production by 10.88%, reaching 354.21 mg/L. Additionally, low temperature and dodecane addition were employed as auxiliary strategies to promote abscisic acid synthesis, resulting in a titer of 605.92 mg/L. Finally, the engineered strain achieved an abscisic acid titer of 2056.64 mg/L in a 5 L bioreactor, representing the highest titer reported for a yeast de novo synthesis system to date.