Determination of Proper Conditions for the Production of Crude Beta-galactosidase Using Lactobacillus delbrueckii ssp. bulgaricus

Proper conditions for producing crude beta-galactosidase from waste materials were de-termined. This enzyme is to be used in the production of lactose-hydrolyzed milk. Whey permeate was used as a basic medium. Twenty seven treatments were developed by ۳ vary-ing factors of: yeast extract (۱, ۲, and ۳ %), wheat steep liquor (۱, ۲, and ۳ %), and whey powder (۰.۵, ۱, and ۱.۵ %). Crude enzyme extract was obtained by sonication of the cells collected from cultivation of Lactobacillus delbrueckii ssp. bulgaricus in various media at ۴۳oC. The beta-galactosidase activity was assessed using Ortho-Nitro-Phenyl-beta-D-galactopyranoside (ONPG). Yeast extract and whey powder had both significant effects (P< ۰.۰۱), while wheat steep liquor proved to be ineffective. Yeast extract had the most pro-nounced effect on the production of beta-galactosidase. The effect of the interactions of yeast extract-whey powder and wheat steep liquor-whey powder were significant at ۵ % level (P< ۰.۰۵), while the effect of the interaction of yeast extract-wheat steep liquor was sig-nificant at ۱% level (P< ۰.۰۱). Interaction effect of the ۳ factors on the production of beta-galactosidae was significant (P< ۰.۰۱). The best combination for production of beta-galactosidase (۴.۹۲۴ U ml-۱) was ۳% yeast extract, ۱.۵% whey powder and ۲% wheat steep liquor.

Keywords:

Beta-galactosidase , Crude enzymatic extract , Lactobacillus bulgaricus , Lactose hydrolysis , Wheat steep liquor , Whey permeate