عنوان مقاله [English]
Beta-galactosidase is one of the most important industrial enzymes capable of decomposing lactose into glucose and fructose. In this study, two strains of Kluyveromyces marxianus (GY101 and BY101) were investigated for the production of the β-galactosidase from whey as a culture media. Whey was inoculated with each strain and examined for enzyme production with aeration at 100 rpm for 144 hours. In order to increase the enzyme production, the effect of adding yeast extract (0.2 and 0.5%), magnesium sulfate (0.5%) and manganese sulfate (0.5%) at 24, 48, 96, 120 and 144 hours at 30°C and 37°C were investigated and the enzyme activity was measured. The highest enzyme production after 144 hours at 30°C with GY101 and BY101 strains by adding yeast extract (0.5%) were 2.25 and 2.18 U/ml, and with magnesium sulfate added 2.12 and 1.94 U/ml, respectively. According to the results of this study, whey cheese is an appropriate environment for the production of the β-galactosidase enzyme using Kluyveromyces marxianus with the presence of yeast extract and magnesium and manganese sulfate as supplements. The best temperature for the production of the enzyme in both strains was 30°C, and the addition of mineral supplements and yeast extract had a positive effect on the production of β-galactosidase. While the GY101 strain was more suitable than BY101 and magnesium sulfate was more suitable than manganese sulfate, and the enzyme activity increased with increasing yeast extract concentration.