Preparation of low lactose prebiotic milk using β-galactosidase from lotus seeds (Nelumbo nucifera)

A novel beta-galactosidase (NelnuGal) was isolated from Lotus (Nelumbo nucifera) seeds for the first time in this study. The enzyme was purified to homogeneity using hydrophobic interaction chromatography and ion exchange chromatography. Purified NelnuGal appeared as a monomer with a molecular mass of 50 kDa on SDS-PAGE gel and zymogram. It was optimally active at pH 4.0 and stable in a broad pH range of 4-10. NelnuGal displayed temperature optimum of 50 degrees C and thermostability from 20 to 50 degrees C It was resistant to inhibition by most of the metal ions tested, especially Ca+2 and Mg+2 making it useful in hydrolysis of milk. Remarkably, NelnuGal was not inhibited by high concentrations of galactose, which is end-product of lactose hydrolysis. The purified NelnuGal displayed lactose hydrolysis and transgalactosylation properties. Addition of lotus seed powder to milk and whey resulted in lactose hydrolysis, forming galactose, glucose and galactooligosaccharides. Therefore, the addition of lotus seed powder to milk and whey can be applied for reducing the lactose present in dairy products which will also have potential prebiotic properties.

Automated summary

A novel beta-galactosidase, NelnuGal, was isolated from Lotus seeds for the first time. It was purified to homogeneity using hydrophobic interaction chromatography and ion exchange chromatography. NelnuGal exhibited optimal activity at pH 4.0, broad pH stability (pH 4-10), and temperature optimum of 50°C with thermostability from 20 to 50°C. The enzyme showed resistance to inhibition by most metal ions, making it useful for milk hydrolysis.