Effective bioconversion of sophoricoside to genistein from Fructus sophorae using immobilized Aspergillus niger and Yeast.

In this study, sophoricoside from Fructus sophorae was highly bioconversed to genistein by co-immobilized Aspergillus niger and Yeast. Bioconversion conditions for genistein were optimized with single-factor experiments. The optimal conditions were as follows: microbial concentration 1.5 × 10(7) cells/mL, wet weight of microorganisms beads 10.0 g/g material, pH 5, ratio of liquid to solid 25:1 (mL/g), temperature 32 °C and time 24 h. Under these conditions, a 34.45-fold increase in production of genistein was observed with a bioreactor. Moreover, the antioxidant activities of the extracts from the fermented and untreated F. sophorae were 0.287 ± 0.11, 0.384 ± 0.08 mg/mL (IC50) and 1.84 ± 0.13, 1.28 ± 0.25 mmol Fe(II)/g, according to the DPPH test and FRAP assay, respectively. The results indicated that the method described in the current work were valuable procedure for the production of genistein, which is of most importance for industrial scale applications as well as food industry.