Immobilization of Β-galactosidase of Kluyveromyces lactis in mesoporous silica

Abstract

β-galactosidase has been immobilized in different supports to improve its industrial performance. Thus, the research aimed to evaluate the covalent immobilization process of β-galactosidase from Kluyveromyces lactis in silica. The best immobilization conditions were evaluated based on the initial enzymatic activity, concentration of (3-Aminopropyl)triethoxysilane (APTES), and glutaraldehyde concentration using a central rotational composite design (CCRD). The influence of temperature and pH on enzymatic activity, thermal stability, pH, storage, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and reuse were also studied. The best immobilization conditions were at a concentration of 1.0 % APTES and 6.86 % glutaraldehyde, and an initial enzymatic activity of 21 U.mL⁻¹. The immobilized β-galactosidase showed an optimal pH of 7.0, temperature of 30°C, and stability at pH of 7.5. Thermal stability was better at 20°C. In four reuse cycles, the enzyme maintained approximately 70 % of its initial activity. The stored enzyme (8°C) maintained 44 % activity after 105 days. The FT-IR allowed the visualization of the enzyme groups and the enzyme-support binding. SEM images showed the structure of the silica Using a fixed bed reactor, a lactose conversion of roughly 47 % was obtained. In general, the proposed method was efficient in lactose hydrolysis. Silica is considered a promising support for immobilizing β-galactosidase.