[Study on isoflavone active aglycone preparation by immobilized beta-glucosidase from Aspergillus niger]

With sodium alginate as a carrier and glutaraldehyde as the crosslinking agent, an improved immobilization method of beta-glucosidase for production of soybean genistein was developed. As compared with entrapment or entrapment-crosslinkage, crosslinkage-entrapment that beta-glucosidase was treated with glutaraldehyde and then entrapped in sodium alginate remained high loading efficiency and activity recovery, Effects of bead sizes, concentrations of alginate and glutaraldehyde as well, on the loading efficiency and activity recovery were assessed. When compared with the free enzyme, the optimum temperature, pH value and Km of the immobilized beta-glucosidase were respectively shifted from 50 degrees C to 40 degrees C, 4.5 to 4.0 and 2.57 microg/mL to 2.02 miocrog/mL. The stabilities of the immobilized beta-glucosidase were considerably better than that of the native enzyme. The immobilized beta-glucosidase was employed to genistein production, 84.94% of the activity and 56.04% of conversion were kept after consecutive use of 6 times.