Bioprocess optimization enables enhanced protopanaxadiol production in yeast

Ginsenosides are the primary active metabolites of ginseng and have been used in traditional herbal medicine in Asia for more than 4,000 years. Protopanaxadiol (PPD) is the precursor of dammarane-type ginsenosides, exhibiting different pharmacological activities. However, extraction of PPD from plant material is cumbersome because of its low concentration. Precision fermentation using recombinant yeast is a promising alternative strategy to produce PPD. For increasing PPD production, the medium and fermentation conditions were optimized by a Design of Experiment (DoE) approach. PPD production increased by 7.5-fold in the final cultivation condition compared to the reference condition. The PPD titer reached 1.2 g/L during simple 500 mL shake flask cultivations, the highest PPD production in shake flasks to date. The protocol presented facilitates parallel evaluation of recombinant yeast, thereby contributing to the much-needed sustainable synthesis of the versatile molecule class of triterpenoids.