Mass Production of Ginsenosides in Saccharomyces cerevisiae

Ginseng is a medicinal herb that requires cultivation under shade conditions, typically for 6 yr, before harvesting. The principal components of ginseng are ginsenosides, glycosylated tetracyclic terpenes. Ginsenosides are classified into two groups, protopanaxadiol (PPD) and protopanaxatriol (PPT), based on their hydroxylation patterns, and further diverge to diverse ginsenosides through differential glycosylation. Three early enzymes, Dammarenediol-II synthase (DS) and two P450 enzymes, protopanaxadiol synthase (PPDS) and protopanaxatriol synthase (PPTS), have been reported, but glycosyltransferases that are necessary to synthesize specific ginsenosides have not yet been fully identified. To discover glycosyltransferases responsible for ginsenoside biosynthesis, we sequenced and assembled the ginseng transcriptome de novo and identified three UDP-glycosyltransferases (PgUGTs): PgUGT74A1, PgUGT94B1 and PgUGT31. Ginsenoside synthetic pathways were constructred in S. cerevisiae to develop yeast strains producing minor ginsenosides. We were able to produce various ginsenosides through fed-batch fermentation using developed yeast strains