Effects of aeration rate on the production of ergosterol and blazeispirol A by Agaricus blazei in batch cultures

Ergosterol and blazeispirol A are important bioactive components of Agaicus blazei; however, little work in the literature focused on culture conditions on their production. The main aims of this study were to clarify the influence of oxygen transfer rate on cell growth and the production of ergosterol and blazeispirol A and the conversion ratio of ergosterol into blazeispirol A. The optimal aeration rate for cell growth was obtained at 0.4 vvm, while those for ergosterol and blazeispirol A formation were at 0.2 and 0.3 vvm, respectively. The cell growth and blazeispirol A formation favored at higher oxygen supply; but ergosterol formation favored at lower oxygen supply. Results of this study demonstrated oxygen supply played an important role not only in cell growth but also in ergosterol and blazeispirol A formation. A novel fermentation process of blazeispirol A of A. blazei was proposed using a novel parameter, the conversion ratio of ergosterol into blazeispirol A.