β-galactosidase production by Saccharomyces fragilis IZ 275 in cheese whey

Abstract

Cheese whey is a byproduct of dairy industry rich in lactose, minerals and proteins which can be used as fermentation medium for microorganism. The parameters of fermentation (pH, temperature and inoculum) have not so far been optimized. Thus, the objective of this study was to investigate the temperature, pH and inoculum concentrations parameters using a Central Composite Rotational Design (CCRD) 23 and Response Surface Methodology (RSM) to ?-galactosidase production in cheese whey by Saccharomyces fragilis IZ275. The ?-galactosidase production by S. fragilis IZ 275 was evaluated through the enzymatic activity (U mL-1) using o-nitrophenyl-?-D-galactopyranoside substrate (ONPG). All the studied variables were significant and therefore the quadratic model was adequate to explain the effects of the three variables (X1, X2 and X3) on the response function (Y1 = ?-galactosidase activity). The incubation at 35 °C of temperature, pH 6.0 and 20% inoculum concentration guarantees the maximum production ?-galactosidase by Saccharomyces fragilis IZ 275 in supplemented cheese whey.