Plant secondary metabolites are an important source of active ingredients for food, cosmetic and pharmaceutical industry. They are frequently decorated with sugars resulting in both increased stability and water solubility of the glycoside product that also show unique targeting effects and altered activity when compared to the original scaffold. Glycosides are formed by the action of glycosyltransferases (GTs) which are a ubiquitous group of enzymes that catalyze the transfer of a sugar moiety from an activated sugar donor, usually UDP-glucose to acceptor molecules usually an alcohol. We developed a method for the targeted functional characterization of GT genes and succeeded in the identification of the first terpene GT genes from grapevine (Vitis vinifera) whose encoded proteins showed unprecedented monoterpenol GT activities and glucosylated a broad range of acceptors (e.g. geraniol, citronellol, nerol). Preliminary studies on laboratory scale proved that the novel genes are good candidates to develop a bioprocess for the production of small molecule glucosides with recombinant E. coli.
The goals of our project are the establishment of an efficient and scalable bioprocess for the production of whole-cell GT biocatalysts, the design of the biocatalytic process step for the production of small molecule glucosides (e.g. geranyl glucoside), and up-scale to a prototype scale.