Biosynthesis Of Squalene Type Triterpenoids By Saccharomyces Cerevisiae

Squalene type triterpenoids not only exhibit significant biological activities including anti-cancer and anti-oxidation,but also have a wide application in drug delivery and skin care.Thus,efficient biosynthesis of squalene type triterpenoids is extremely important.In this study,we discovered that the fermentation extracts from Saccharomyces cerevisiae expressing cytochrome P450(CYP)gene cyp505d13 from Ganoderma lucidum generated multiple new UPLC peaks,compared to that from control strain harboring vector plasmids.After large-scale fermentation,products extraction,products isolation via silica gel column chromatography and semi-preparative HPLC,and nuclear magnetic resonance analyses,we identified the structures of three main compounds.They were two newly discovered squalene type triterpenoids,4,8-dihydroxy-22,23-oxidosqualene(ST-1),8-hydroxy-2,3;22,23-squalene dioxide(ST-2),and one known squalene type triterpenoid 2,3;22,23-squalene dioxide(ST-3).After optimization of the fermentation medium,the engineered yeast strain was able to produce ST-1,ST-2 and ST-3 at the titers of 3.54 mg/L,31.65 mg/L and 38.21 mg/L after 96 h fermentation,respectively,in medium containing 2%(wt/vol)glucose and 2%(wt/vol)glycerol.In addition,the in vitro enzymatic reaction suggested that CYP505D13 is involved in ST-3 biosynthesis.This study lays a foundation for the efficient biosynthesis of ST-1,ST-2 and ST-3 and their potential application,and provides a reference for the discovery of squalene type triterpenoids and their biosynthetic enzymes.