Microbial transformation of phytosterol in corn flour and soybean flour to 4-androstene-3,17-dione by Fusarium moniliforme Sheld

A strain that was capable of transforming the phytosterol in corn flour and soybean flour was isolated from soil and identified as Fusarium moniliforme Sheld. The main transformation product was purified by high performance liquid chromatography (HPLC), and was characterized by nuclear magnetic resonance (NMR), mass spectrum (MS), and infrared spectrum (IR). The results indicated that the product was 4-androstene-3,17-dione (AD). The production of AD was increased with the increase of initial concentration of corn flour while the yield of AD was decreased. The yield of AD was lower in the media with only soybean flour. Sulfate–phosphate–ferric method (SPF) was first used for determination of the total phytosterol content in corn flour or soybean flour. The measured value by SPF method matched reasonably well with that by HPLC, which indicated the validity of SPF method.