A sustainable strategy for biosynthesis of Rebaudioside D using a novel glycosyltransferase of Solanum tuberosum

Abstract Bioconversion of Rebaudioside D faces high‐cost obstacles. Herein, a novel glycosyltransferase StUGT converting Rebaudioside A to Rebaudioside D was screened and characterized, which exhibits stronger affinity and substrate specificity for Rebaudioside A than previously reported enzymes. A whole‐cell catalytic system was thus developed using the StUGT strain. The production of Rebaudioside D was enhanced significantly by enhancing cell permeability, and the maximum production of 6.12 g/L and the highest yield of 98.08% by cell catalyst was obtained by statistical‐based optimization. A new cascade process utilizing this recombinant strain and E. coli expressing sucrose synthase was further established to reduce cost through replacing expensive UDPG with sucrose. A StUGT‐GsSUS1 system exhibited high catalytic capability, and 5.27 g L −1 Rebaudioside D was achieved finally without UDPG addition by systematic optimization. This is the best performance reported in cell‐cascaded biosynthesis, which paves a new cost‐effective strategy for sustainable synthesis of scarce premium sweeteners from biomass.