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Two strains of Lactobacillus(L.) casei and one strain of L. pentosus, which were isolated from pickles, were used to investigate in studing their characteristics of β-galactosidase. The preferable carbon sources and pH of the MRS media for enzyme production from L. casei No.10 was found to be 1.0% galactose and pH 7.5, from L. pentosus No.63 was 1.0% galactose and pH 7.5, and from L. casei No.36 was 1.0% lactose and pH 6.5, respectively. The maximum enzyme production from each strain was found after 48 hours culture at 30℃ in a medium with preferable carbon source. The optimum reaction temperature with substrate for β-galactosidase activity was found at 60℃ for all three strains . The stability of enzyme from L. casei No. 36 was found to be at 45℃, from L. pentosus No.63 was found at 55℃. This stability from L. casei No.36 was found at 40℃, but it was reduced to 60% at 55℃. These stabilities of enzymes remained about 90% at 40℃ for all three strains. The optimal pH for enzyme activities was found to be pH 6.5 for all three strains. Enzyme activity remained over 90% for L. casei No.10 at pH 5.0∼6.0, for L. casei No.36 at pH 5.0∼8.0, and for L. pentosus No.63 at pH 6.0∼7.0.
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