Beta-glycosidase enzyme activities of lactobacillus and bifidobacterium genus and hydrolysis of isoflavone

In this study, human-being, nutritional and animal originated 39 pieces Lactobacillus and isolated from new-born faeces 3 Bifidobacterium, a total of 42 bacterias that are available in the culture collection of Biotechnology Laboratory of Faculty of Science in Gazi University are used. By using p-nitro phenyl-ß-D glikopiranozit (p-NPG) as a substrate, ß-glycosidase enzyme activities of the cultures were identified. It is registered that animal-originated Lactobacillus rhamnosus BAZ78 (4,500±0,002 U/mg), belonging to Lactobacillus family, nutritional Lactobacillus rhamnosus SMP6-5 (2,670±0,001 U/mg), human-being originated Lactobacillus casei LB65 (3,000±0,001 U/mg) and Lactobacillus casei LE4 (2,000±0,001 U/mg) strains, on the other hand Bifidobacterium breve A28 (2,670±0,000 U/mg) and Bifidobacterium longum BASO15 (2,330±0,000 U/mg) strains belonging to the Bifidobacterium family have the highest specific enzyme activity capabilities. Optimization studies were carried out on the cultures that showing a high ß-glycosidase enzyme activity, identifying that different pH, temperature, buffer, and nutritional environment have an effect on the enzyme activity. It is observed that, cultures at pH 7.5 have the highest (Lactobacillus rhamnosus BAZ78, 4,500±0,002 U/mg), and at pH 4.0 have the minimum (Bifidobacterium breve A28, 0,750±0,000 U/mg) specific enzyme activity capability. To determine the effect of temperature on enzyme activity, p-nitrophenyl-ß-D-glukopiranozit (p-NPG) mixtures are incubated at a temperature of 30° C, 37 º C, 40 º C, 50 º C and 60 º. It is seen that, cultures which are close to the incubation temperatures, records a high enzyme activity. In the case of strains are grown up in different nutritional environment, while strain Lactobacillus casei LB65 (6,800±0,001 U/mg), in the 2% fructose containing nutritional environment shows the highest enzyme activity, strain Lactobacillus casei LB65 (0,460±0,002 U/mg) in the 2% cellobiose containing nutritional environment shows the lowest enzyme activity. On the other hand, while the highest specific enyzme acvitivy in Bifidobacteriums are registered in the TPY nutritional environment (Bifidobacterium breve A28, 2,670±0,000 U/mg), the lowest specific enyzme activity is registered in the MMRSC nutritional environment (Bifidobacterium longum BASO15, 0,720±0,001 U/mg). It is determined that, cultures considered as a potential probiotic strains, under adverse conditions in the gastro-intestinal system (acid, bile salts) showed high ß-glucosidase activity, while preserving the viability. In the artificial gastric juice, cultures of Lactobacillus and Bifidobacterium showed the highest (Lactobacillus casei LB65, 2.200 ± 0.005 U / mg) at pH 7.0, and at pH 2.0 the lowest (Lactobacillus rhamnosus BAZ78, 0,603 ± 0,000 U / mg) specific enzyme activity. In artificial intestinal fluid, at At pH 8.0, Bifidobacterium breve strain A28 (1.280 ± 0.003 U / mg) shows the highest specific ß-glucosidase enzyme activity, while the lowest specific enzyme activity is seen, at pH 5.5, on LE4 strain of Lactobacillus casei (0 ,5100 ± 0.008 U / mg). Purification process has been applied to determine the purity degree of the enzyme of Lactobacillus rhamnosus (BAZ78) strain, which has the highest enzyme activity capability among the ß-glucosidase activity showing bacterial cultures. With high performance liquid chromatography (HPLC), it is identified, strains having high enzyme activity could not hydrolyze glucoside isoflavone form (daidzin, genistin) to aglikon form (daidzein, genistein) forms.