Efficient synthesis of salidroside using mined glycosyltransferase through cascade reaction

Salidroside has been widely utilized in the food and cosmetics industries. However, the efficient synthesis of salidroside remains a challenge. In this study, a potential uridine diphosphate-dependent glycosyltransferase (UGT) from Bacillus subtilis 168 (named UGT_BS) was identified through evolutionary relationship analysis and molecular docking, with findings subsequently validated by experimental verification. The optimal conversion of UGT_BS for salidroside synthesis reached 98.4% (mol/mol). Additionally, a conversion exceeding 85% (mol/mol) was achieved using the UGT_BS-AtSuSy cascade reaction with tyrosol concentrations ranging from 1 to 10 mM, demonstrating the substrate tolerance of UGT_BS at high concentrations. Kinetic determination and molecular docking confirmed that the strengthened hydrogen bonds and suitable active center conformation between the enzyme and substrate may account for the efficient synthesis of salidroside. Furthermore, 43.5 mM of salidroside was obtained using a fed-batch cascade reaction strategy. The UGT_BS identified in this study shows significant potential for salidroside synthesis, and the strategy employed here serves as a reference for the discovery of related enzymes.