Factors influencing synthesis and activity of β-galactosidase inLactobacillus acidophilus

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Abstract
In the type-strainLactobacillus acidophilus ATCC 4356 β-galactosidase (β-gal) was inducible; lactose, galactose, melibiose and probably maltose, but not glucose, fructose, mannose, sucrose and cellobiose, induced β-gal synthesis. Glucose partially inhibited β-gal-induction by lactose but not by isopropyl-β-D-thiogalactoside. β-gal synthesis during cell growth was maximal at 0.4% lactose, stimulated by Ca2+ but inhibited by Mg2+ and Mn2+. β-gal in the cell-free extract had optimum activity at pH 6.5 and at 45°C. The enzyme activity was stimulated by Mg2+, inhibited by Ca2+, destroyed by oxidizing agents and protected by reducing agents.