Abstract: Cross-linked enzyme aggregates (CLEAs) were used to immobilize β-glucosidase from Aspergillus niger. β-glucosidase was precipitated by 90% ammonium sulfate solution for 30 min at 0 ℃, then the aggregates were cross-linked by 5% glutaraldehyde solution. The obtained cross-linked β-glucosidase aggregates remained 75% of total enzyme activity. Its optimum reaction temperature, reaction pH and Km to pNPG were 60 ℃, 4.0 and 4.61×10-3 mol/L, respectively. Compared to the free β-glucosidase, the cross-linked β-glucosidase aggregates had higher affinity to the substrate. The conversion rate was 66% when cross-linked β-glucosidase aggregates were employed to genistein production from soybean isoflavone genistin in 40 min.

Key words: &beta, -glucosidase； cross-linked enzyme aggregates； carrier-free immobilization； soybean isoflavones； application；