Efficient whole-cell biotransformation for gastrodin production via glycosyltransferase engineering and process optimization

Gastrodin is a naturally occurring phenolic glycoside derived from Gastrodia elata , which is widely used as an edible medicinal plant in functional foods and dietary supplements in East Asia. Owing to its antioxidant, neuroprotective, and metabolic regulatory activities, gastrodin has attracted increasing attention as a valuable plant-derived glycoside for food and nutraceutical applications. However, its sustainable production is hindered by the limited activity of plant-derived uridine diphosphate-dependent glycosyltransferases (UGTs), the cytotoxicity of p -hydroxybenzyl alcohol (pHBA), and insufficient intracellular supply of UDP-glucose (UDPG). In this study, an efficient whole-cell biotransformation strategy was developed by integrating glycosyltransferase engineering with host metabolic optimization to enhance gastrodin biosynthesis. A triple mutant UGT variant, M4 (N94L/N221G/I343V), exhibiting 50.1% higher catalytic activity than the wild-type enzyme, was obtained through experimental screening. The cytotoxic effects of pHBA were systematically evaluated to define an optimal substrate loading range for high efficiency conversion. Furthermore, intracellular UDPG availability was enhanced using a push-pull strategy that combined a UDPG regeneration module with deletion of the competing pgm gene. Under optimized conditions, the engineered strain achieved a gastrodin titer of 79.9 mM (equivalent to 22.9 g/L) in a 1 L fermenter within 12 h, corresponding to a space-time productivity of 1.9 g/L/h. This work provides a sustainable and scalable biomanufacturing approach for the production of plant-derived phenolic glycosides.