Highly Efficient Biosynthesis of Salidroside by a UDP-glucosyltransferase-catalyzed Cascade Reaction

Abstract Objective Salidroside is an important plant-derived aromatic compound with diverse biological properties. The main objective of this study was to synthesize salidroside from tyrosol using UDP-glucosyltransferase (UGT) with in situ regeneration of UDP-glucose (UDPG). Results The UDP-glucosyltransferase 85A1 (UGT85A1) from Arabidopsis thaliana,which showed high activity and regioselectivity towards tyrosol, was selected for the production of salidroside. Then, an in vitro cascade reaction for in situ regeneration of UDPG was constructed by coupling UGT85A1 to sucrose synthase from Glycine max (GmSuSy). The optimal UGT85A1-GmSuSy activity ratio of 1:2 was determined to balance the efficiency of salidroside production and UDP-glucose regeneration. Different cascade reaction conditions for salidroside production were also determined. Under the optimized condition, salidroside was produced at a titer of 6.0 g/L with a corresponding molar conversion of 99.6% and a specific productivity of 199.1 mg/L/h in a continuous feeding reactor. Conclusion This is the highest salidroside titer ever reported so far using biocatalytic approach.