Utilizing genetically engineered bacteria to produce plant-specific glucosides

Plant-derived glucosides have attracted much attention due to their widespr ead applications. This class of products is difficult to isolate or to synt hesize in pure form because of the resulting low yields. Thus, simple appro aches for the generation of such glucosides would be highly beneficial. We purified and characterized a novel glucosyltransferase from plant cell susp ension cultures of Rauvolfia serpentina, which showed rather low substrate specificity. We obtained its cDNA and expressed the active recombinant prot ein in bacteria (Escherichia coh) with excellent plant-specific glucosylati on efficiencies. Compared with the plant system, the bacteria delivered the new enzyme, which was in the form of a soluble or matrix-bound enzyme, app roximately 1800 times more efficiently for the synthesis of a wide range of glucosides. More importantly, the engineered E. coli strain allowed for in vivo glucosylation and release of the product into the culture medium, as shown by the formation of arbutin, which is a potent inhibitor of human mel anin biosynthesis with commercial value. (C) 2001 John Wiley & Sons, Inc.