Substrate consumption and beta-galactosidase production by Saccharomyces fragilis IZ 275 grown in cheese whey as a function of cell growth rate

Abstract

Abstract Microfiltrated cheese whey permeate (CWP) was used as substrate by Saccharomyces fragilis IZ 275 yeast for the production of beta-galactosidase. Yeast growth kinetics was evaluated by lactose consumption, biomass production and, enzyme production. Lactose was almost depleted within 12 h of cultivation, only 11% of the substrate was left in the culture medium, indicating an average intake rate of 2.63 g.L−1.h−1 (lactose consumed/fermentation time). Biomass production increased with increasing cultivation time, reaching 11.06 mg.mL−1 and a specific growth rate (μ) of 0.317.h−1 in 20 h of cultivation. The maximum yield of volumetric and specific beta-galactosidase activity was 14.28 U.mL−1 and 0.039 U.mg−1, respectively, and maximum lactose hydrolysis was obtained at 24 h of cultivation. This work evaluated the importance of the microfiltration process of cheese whey in Saccharomyces fragilis IZ 275 fermentation for beta-galactosidase production.