摘要：In this study total 42 bacteria were used; 39 Lactobacilllus originated from human, food and animal and 3 Bifidobacterium isolated from new born baby feces. The β-galactosidase enzyme activities and specific activities were determined by using o-nitrophenyl-b-D-galactopyranoside (o-NPG) as a substrate. The highest specific enzyme activities observed among Lactobacilli cultures were at L. fermentum ZYN17 (2.468 U/mg), L. casei LB65 (1.116 U/mg), L. rhamnosus GD11 (1.034 U/mg), and L. acidophilus BAZ36 (0.947 U/mg) strains and the highest enzyme activities observed among Bifidobacterium was at B. breve A26 (0.726 U/mg) strain. The enzyme activities of bacteria were also determined qualitatively by using the 5-bromo-4-chloro-3-indolyl-β-D-galaktoside (X-gal) substrate compound. The enzyme optimization of ZYN17 strain with highest specific β-galactosidase activity was achieved. The optimum pH was determined as 6.8, optimum temperature was 37 ºC and the optimum buffer was potassium phosphate buffer for the enzyme.
