Removal of lactose in crude galacto-oligosaccharides by β-galactosidase from Kluyveromyces lactis

Publication date: Available online 25 July 2016 Source:Journal of Molecular Catalysis B: Enzymatic Author(s): Luciana Santibáñez, Lucía Fernández-Arrojo, Cecilia Guerrero, Francisco J. Plou, Andrés Illanes In order to remove the residual lactose in crude galacto-oligosaccharides (GOS), different commercial soluble β-galactosidases from Kluyveromyces lactis (Lactozym Pure 6500L, Maxilact L2000, Lactase NL and Biolactasa-NL) and reaction conditions (temperature, total carbohydrate concentration and enzyme:substrate mass ratio) were evaluated. To select the best biocatalyst, the hydrolytic activity on o-NPG and thermal stability of all enzymes were evaluated in the absence and presence of three cations (Co2+, Mg2+, Mn2+) at different concentrations. The enzyme source, cation and cation concentration were selected to obtain the highest hydrolytic activity and thermal stability. then lactose hydrolysis of raw GOS was assessed varying the temperature (30°C–45°C), total carbohydrate concentration (10%-50%) and enzyme:substrate mass ratio (50 IU·g−1-400 IU·g−1) and considering the lactose percentage decrease as response parameter (DL). Lactase NL was selected as the best enzyme, with a hydrolytic activity of 286 IU·mg−1 and a half-life of 9hours at 35°C in the presence of 1mM Mn2+. The best reaction conditions for lactose hydrolysis employing the selected enzyme were 35°C, 50% of initial carbohydrate concentration and 135 IU·g−1. At such conditio...
Source: Journal of Molecular Catalysis B: Enzymatic - Category: Biochemistry Source Type: research