Multi-modular engineering ofSaccharomyces cerevisiaefor high-titre production of tyrosol and salidroside

Tyrosol and its glycosylated product salidroside are important ingredients in pharmaceuticals, nutraceuticals and cosmetics. Despite the ability ofSaccharomyces cerevisiaeto naturally synthesize tyrosol, high yield fromde novosynthesis remains a challenge. Here, we used metabolic engineering strategies to constructS. cerevisiaestrains for high-level production of tyrosol and salidroside from glucose. First, tyrosol production was unlocked from feedback inhibition. Then, transketolase and ribose-5-phosphate ketol-isomerase were overexpressed to balance the supply of precursors. Next, chorismate synthase and chorismate mutase were overexpressed to maximize the aromatic amino acid flux towards tyrosol synthesis. Finally, the competing pathway was knocked out to further direct the carbon flux into tyrosol synthesis. Through a combination of these interventions, tyrosol titres reached 702.30 +/- 0.41 mg l(-1)in shake flasks, which were approximately 26-fold greater than that of the WT strain.RrU8GT33fromRhodiola roseawas also applied to cells and maximized salidroside production from tyrosol inS. cerevisiae. Salidroside titres of 1575.45 +/- 19.35 mg l(-1)were accomplished in shake flasks. Furthermore, titres of 9.90 +/- 0.06 g l(-1)of tyrosol and 26.55 +/- 0.43 g l(-1)of salidroside were achieved in 5 l bioreactors, both are the highest titres reported to date. The synergistic engineering strategies presented in this study could be further applied to increase the production of high value-added aromatic compounds derived from the aromatic amino acid biosynthesis pathway inS. cerevisiae.