β-Galactosidase production using glycerol and byproducts: Whey and residual glycerin

Abstract

The present study aimed to evaluate β-galactosidase production by liquid-state fermentation using an experimental design and response surface methodology. A culture medium containing lactose and analytical grade glycerol was formulated to maximize β-galactosidase production. The effects of the pH, lactose, and glycerol concentration on the enzyme production were studied using a Central Composite Design (CCD; 23 plus central points), followed by a Central Composite Rotatable Design (CCRD; 23 plus axial and central points). The conditions that maximized β-galactosidase production were: lactose concentration of 20 g L−1, glycerol concentration of 60 g L−1, and pH 5.0. Under these conditions, the highest enzymatic activity was 40.7 U mL−1. Glycerol and lactose were replaced by residual glycerin and whey respectively, according to the best condition obtained in CCRD, reaching enzymatic values of 31.8 U mL−1, and thus demonstrating to be great alternative sources for β-galactosidase production.