Purification and catalytic behavior optimization of lactose degrading β-galactosidase from .

The β-galactosidase is an industrially valuable enzyme and used to hydrolyze the lactose into glucose and galactose. Considering the broad utility profile in food industry, β-galactosidase from was purified and characterized in term of its catalytic properties and stability. It displayed highest catalytic efficiency at 60 °C after 10.0 min within acidic pH environment (pH 5). The β-galactosidase exhibited 100% and 60% catalytic activity at 40 °C and 50 °C, respectively even after 120.0 min. The β-galactosidase activity was remained stable in the presence of Zn, Ni, and Mg ions. The activity was also retained in all investigated organic solvents except DMSO at various ionic concentrations. The surfactants Triton X-100 and SDS caused positive impact on the catalytic activity of enzyme at 1.0 mM concentration. However, the percent relative activity of β-galactosidase was significantly reduced when incubated with EDTA. The molecular mass of β-galactosidase estimated to be 95 kDa. The SEM micrographs of ONPG before and after β-galactosidase treatment indicated a remarkable difference in the morphology and proved the strong catalytic strength of enzyme. The β-galactosidase also demonstrated exceptional storage stability at - 80 °C, - 20 °C and 4 °C by retaining 86, 79 and 70% activity even after 100.0 days.