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Production and optimization of â-galactosidase enzyme from probiotic Lactobacillus sps.

M.Charitha Devi, N.S.Meera, P.Charan Theja, D.V.R.Sai Gopal

â-galactosidase enzyme (EC 3.2.1.23) has been used in dairy industry for the improvement of lactose intolerance. The production of â-galactosidase enzyme by probiotic Lactobacillus spp., was studied and their ability to hydrolyse 5-bromo-4-chloro-3-indolyl-â-D-galactopyranoside (X-Gal) and ONPG was determined. Crude enzyme extract was obtained by the lysis of the cell using lysis buffer. The â-galactosidase enzyme activity was assessed using Ortho-nitrophenyl-beta-D-galactopyranoside (ONPG) as an enzyme substrate. Aprotein band indicated â-galactosidase enzyme was detected by SDS-PAGE method. The â-galactosidase appeared as a single protein band in SDS-PAGE with a molecularmass of approximately 116 kDa. Lactobacillus spp., produced blue colour colonies onX-Gal plates shows â-galactosidase positive results. The optimum pH and temperature for the â-galactosidase production were pH 5 (156 U/ml) and 350C (86 U/ ml). The intracellular concentration of â-galactosidase enzyme increased linearly with increasing lactose concentration upto 7 %(172 U/ml) and by utilising yeast extract as nitrogen source (98 U/ml). Substitution of Lactobacillus spp., producing â-galactosidase enzyme as probiotic to dairy products, could help lactose intolerant people. One variable at a time approach method was used for the optimization of medium components for the production of â-galactosidase by submerged fermentation in a semi-synthetic medium.