Aspergillus oryzae β-D-galactosidase immobilization on glutaraldehyde pre-activated amino-functionalized magnetic mesoporous silica: Performance, characteristics, and application in the preparation of sesaminol.

Aspergillus oryzae β-D-galactosidase (β-Gal) efficiently hydrolyzes sesaminol triglucoside into sesaminol, which has higher biological activity. However, β-Gal is difficult to be separate from the reaction mixture and limited by stability. To resolve these problems, β-Gal was immobilized on amino-functionalized magnetic nanoparticles mesoporous silica pre-activated with glutaraldehyde (FeO@mSiO-β-Gal), which was used for the first time to prepare sesaminol. Under the optimal conditions, the immobilization yield and recovered activity of β-Gal were 57.9 ± 0.3 % and 46.5 ± 0.9 %, and the enzymatic loading was 843 ± 21 U/g. The construction of FeO@mSiO-β-Gal was confirmed by various characterization methods, and the results indicated it was suitable for heterogeneous enzyme-catalyzed reactions. FeO@mSiO-β-Gal was readily separable under magnetic action and displayed improved activity in extreme pH and temperature conditions. After 45 days of storage at 4 °C, the activity of FeO@mSiO-β-Gal remained at 92.3 ± 2.8 %, which was 1.29 times than that of free enzyme, and its activity remained above 85 % after 10 cycles. FeO@mSiO-β-Gal displayed higher affinity and catalytic efficiency. The half-life was 1.41 longer than free enzymes at 55.0 °C. FeO@mSiO-β-Gal was employed as a catalyst to prepare sesaminol, achieving a 96.7 % conversion yield of sesaminol. The excellent stability and catalytic efficiency provide broad benefits and potential for biocatalytic industry applications.