Systematic Metabolic Engineering of Oleaginous Yeast <i>Yarrowia lipolytica</i> for Efficient Synthesis of Polyketide 6-Methylsalicylic Acid

The polyketides 6-methylsalicylic acid (6-MSA) exhibits good resistance to plant pathogens and considerable application potential. However, conventional methods, such as plant extraction, have limited its industrialization and green synthesis. Microbial synthesis of 6-MSA is a novel and efficient preparation method. In this study, <i>Yarrowia lipolytica</i> was engineered by introducing the 6-MSA synthase gene (6-MSAS) and its activating partner 4'-phosphopantetheinyl transferase, along with the enhancement of precursor synthesis and substrate utilization genes, combined with genome multicopy integration strategies, resulted in the titer of 6-MSA to 3.93 g/L. Finally, through the implementation of xylose-induced biosynthesis modules and fermentation, the titer of 6-MSA was increased to 5.71 g/L in shake flasks and 25.88 g/L in a 5 L bioreactor, representing the highest yield reported to date. This study successfully demonstrated the potential for the synthesis of 6-MSA catalyzed by polyketide synthase I (PKS I) in yeast through systematic metabolic engineering approaches.