Metabolic engineering of Saccharomyces cerevisiae for de novo biosynthesis of hydroxytyrosol and salidroside

ABSTRACT Hydroxytyrosol and salidroside are phenylethanol compounds with significant industrial applications but limited availability due to low-yield natural extraction and complex chemical synthesis. In this study, Saccharomyces cerevisiae was engineered to achieve efficient de novo biosynthesis of these compounds. A tyrosol-producing strain (ZYT1) was optimized to produce 571.8 mg/L tyrosol, which served as the yeast chassis cell for hydroxytyrosol synthesis. By integrating PaHpaB and EcHpaC , strain ZYHT1 produced 304.4 mg/L hydroxytyrosol in shake-flask fermentation, which increased to 677.6 mg/L in a 15 L bioreactor after auxotrophic repair. For salidroside production, glycosyltransferase RrU8GT33 was introduced into ZYT1, yielding strain ZYSAL1 with 48.4 mg/L salidroside. Enhancing UDP-glucose supply using truncated sucrose synthase ( tGuSUS1 ) led to strain ZYSAL9+3, which achieved 1,021.0 mg/L in shake flasks and 18.9 g/L in fed-batch fermentation. This work demonstrates the scalable production of hydroxytyrosol and salidroside in yeast, providing a basis for industrial applications and advancing synthetic biology approaches for natural product biosynthesis. IMPORTANCE Hydroxytyrosol and salidroside are valuable natural compounds with strong antioxidant, anti-inflammatory, and neuroprotective properties, widely used in pharmaceuticals, cosmetics, and health supplements. However, traditional extraction from plants is inefficient, and chemical synthesis is costly and environmentally unfriendly. In this study, we engineered Saccharomyces cerevisiae , a common yeast, to efficiently produce these compounds from simple carbon sources such as glucose and sucrose. By optimizing key biosynthetic pathways, improving cofactor supply, and enhancing sucrose metabolism, we achieved high production levels suitable for industrial applications. Our work provides a sustainable and scalable microbial platform for producing hydroxytyrosol and salidroside, reducing reliance on plant extraction and chemical synthesis. This research advances the field of microbial biotechnology by demonstrating how engineered yeast can serve as a green factory for valuable bioactive compounds, opening new possibilities for large-scale production and commercial use.