Betulinic acid is a pentacyclic lupane-type triterpenoid and a potential antiviral and antitumor drug， but the amount of betulinic acid in plants is low and cannot meet the demand for this compound. Yarrowia lipolytica， as an oleaginous yeast， is a promising microbial cell factory for the production of highly hydrophobic compounds due to the ability of this organism to accumulate large amounts of lipids that can store hydrophobic products and supply sufficient precursors for terpene synthesis. However， engineering for the heterologous production of betulinic acid and related triterpenoids has not developed as systematically as that for the production of other terpenoids， thus the production of betulin... More