Cultural condition affecting the growth and production of â-galactosidase by lactobacillus acidophilus NRRL 4495

The production of P-galactosidase by Lactobacillus acidophilus NRRL 4495 was studied. The highest yield of intracellular P-galactosidase was achieved using acid whey (3.5%) as carbon source after 48h fermentation. Ammonium sulphate (3%) was the best nitrogen source. Addition of MnCl2 at 0.02M optimized the production of the enzyme. In addition, the activity reached 51.46U/g cells when the temperature of the fermentation optimized at 40°C. The highest P-galactosidase activity was obtained by using mechanical disintegration of cells by mortar with sterile sea sand under cooling. By studying some properties of the produced enzyme, the enzyme activity was optimum at 40°C and pH 7.0. In absence of substrate and up to 45°C the enzyme was highly stable, at least for 60 min, retaining 83% of its original activity