Abstract: In this study,the biotransformation products of ursolic acid by Metarhizium anisopliae were isolated and purified.The chemical structure of the isolated product was identified by spectral analysis.The biotransformation conditions were optimized using single factor and orthogonal experiments.The results showed that the main product of the biotransformation process was helvolic acid.The yield of helvolic acid was obviously increased using ursolic acid as the reaction medium.The optimal biotransformation conditions were obtained as follow:28 ℃ as reaction temperature,pH 6.5 and 160 rpm as the rotation speed of the incubator.

Key words: Metarhizium anisopliae, ursolic acid, spectral analysis, helvolic acid