Polyhydroxylated steroids and triterpenoids from an entophytic fungus, Hypocreales sp. NCHU01 isolated from Tuber magnatum

Abstract

The submerged mushroom fermentation process has been used to obtain the mycelial biomass and metabolites for the production of pharmaceutical compounds. In this study, the approach was developed to produce mycelial biomass and triterpenoids in the submerged culture of the truffle entophytic fungus Hypocreales sp. NCHU01. The carbon and nitrogen sources were found to significantly influence the biomass and triterpenoid production. In the carbon source test, 10g/L of sucrose yielded the highest triterpenoid production, reaching 132.26mg/L. In the nitrogen source test, 15g/L of yeast extract was identified as the most favorable source for crude triterpenoid production, reaching 157.68mg/L. In the stimulatory effect, the addition of 2g/L linoleic acid or 125mg/L chitosan to the medium was found to elevate triterpenoid production to 327.5mg/L and 343.2mg/L, respectively. The major sterol compositions of the fruiting body of Tuber magnatum and mycelia of Hypocreales sp. NCHU01 were identified by gas chromatography with a mass spectrometer. It was found that sterol composition in the fermentation mycelia of Hypocreales sp. NCHU01 was quite similar to that of the fruiting bodies of Tuber melanosporum, T. magnatum and T. sinense. Two kinds of sterols (i.e. barrigenol R1; and dehydroepiandrosterone) were identified for the first time from Tuber species in this work. This work proposed the cultivation of entophytic fungus Hypocreales sp. NCHU01 as an alternative resource for T. magnatum from the viewpoint of sterol production.