Preparation of nano-immobilised β-galactosidase using mesoporous silicon dioxide nanoparticles and its efficiency in production of galactooligosaccharides

The β-galactosidase (produced from Aspergillus oryzae) was immobilised on epichlorohydrin functionalised mesoporous silicon dioxide nanoparticles to produce galactooligosaccharides (GOS) from lactose. The characteristic amide bonds and increased particle size confirmed the adsorption of enzyme on nanoparticles. Nano-immobilisation resulted in an increase in enzyme affinity towards the substrate and its hydrolytic property. Free and nano-immobilised enzymes retained 58 and 77% of the original enzyme activity up to 90 days of storage, respectively. The nano-immobilised enzyme exhibited greater stability over a broad range of temperature (30–70 °C) and pH (5.0–8.0). The GOS yield obtained from nano-immobilised enzyme was 2.23 times higher than the free enzyme. GOS production was decreased by 90% and enzyme activity was reduced to 10% in a run of 5 cycles. Overall, the developed nano-immobilisation technique has potential to enhance the stability of the enzyme and GOS production.