In situ immobilization of β-galactosidase from Bacillus circulans in silica by sol-gel process: Application in prebiotic synthesis

The enzyme encapsulation is a very well-known stabilization pathway. However, there are some challenges in order to avoid the enzyme denaturation under encapsulation conditions. The β-galactosidase from Bacillus circulans was immobilized through sol-gel encapsulation route assisted by Triton X-100 surfactant and sugars. The effects of sugar presence in the immobilization process and the gelation time on the biocatalyst activity/stability were explained taking into account the characteristics of the formed silica matrix and the changes of the enzyme environment. The enzyme was effectively immobilized by this strategy, with high immobilization yield in terms of activity (29%) and expressed activity (47 IU/g). The immobilization through silica sol-gel in the presence of 1×10^-3 M Triton X-100 and fructose conferred 28.4-fold higher stability to the enzyme compared with the soluble form. This is an advantage for its use in the synthesis of the galacto-oligosaccharides at 50^oC. The total lactose conversion to galacto-oligosaccharides was 26%wt, which is comparable with that reported in the literature. The obtained biocatalyst is useful for the synthesis of galacto-oligosaccharides and its catalytic behavior is rationalized in this work.