Engineering Escherichia coli for Efficient De Novo Synthesis of Salidroside

Abstract

Salidroside is a high-value plant-derived glycoside with diverse biological activities, but the main industrial salidroside production method, extraction from Rhodiola plants, is insufficient to meet the growing market demand. The biosynthetic route via microbial fermentation is a sustainable and eco-friendly alternative method. De novo synthesis of the precursor tyrosol was established by introducing the ARO10 and ADH6 genes. Systematic metabolic engineering resulted in 3.0 g/L tyrosol, but accumulated tyrosol inhibited cell growth. Adaptive evolution produced an evolved strain with a 10.0% higher OD 600 and a 3.3 g/L tyrosol titer. Introducing glucosyltransferase AtUGT85A1, and overexpressing phosphoglucose mutase pgm and UDP-glucose pyrophosphorylase galU, achieved de novo synthesis of salidroside. Furthermore, AtUGT85A1 was semirationally engineered, resulting in the A21G mutation, which enhanced salidroside production by 31.2%. The optimally engineered strain produced 16.8 g/ L salidroside with 0.4 g/(L h) productivity in a 5 L bioreactor. This study laid a foundation for future industrial production of salidroside and provided important guidance for efficient biosynthesis of other tyrosol derivatives.