EXTRACTION AND PURIFICATION OF β -GALACTOSIDASE FROM A LOCAL ISOLATE OF LACTOBACILLUS ACIDOPHILUS

The aim of the present study was conducted to study the purification of β-galactosidase isolated from local isolate Lactobacillus acidophilus have been used in the dairy industry for the improvement of lactose intolerance. The β-galactosidase produced Lactobacillus acidophilus was extracted and purified by precipitation with ammonium sulphate and dialysis followed by gel filtration using sephadex G-200 chromatography. The result found the ammonium sulfate (80%) was selected as the best ratio for the precipitate of lactase enzyme. These purification steps raised the specific activity to (0.00000108) U/mg in precipitation step with purification folds (4.7) and yield (73%). The specific activity increased in dialysis step to (0.00000154) U/mg with purification fold (6.7) and yield (55.7%). In gel filtration step, the specific activity increased to (0.0000075) U/mg with purification fold (6.9) and yield (33.9%). The molecular weight of purified lactase approximately 93 KDa using the SDS-PAGE