Optimization of β-galactosidase production from lactic acid bacteria

β-galactosidase, commonly known as lactase, represents commercially important enzyme that is prevalently used for lactose hydrolysis in milk and whey. To the date, it has been isolated from various sources. In this study different strains of lactic acid bacteria were assessed for their β-galactosidase productivity, and Lactobacillus acidophilus ATCC 4356 resulted with the highest production potential. Thereafter, optimal conditions for accomplishing high yields of β-galactosidase activity were determined. Maximal specific activity (1.01 IU mL) was accomplished after 2 days shake flask culture fermentation (150 rpm) at 37 °C, with modified Man Rogosa Sharpe culture broth using lactose (2.5%) as sole carbon source. Finally, in order to intensify release of intracellular β-galactosidase different mechanical and chemical methods were conducted. Nevertheless, vortexing with quartz sand (150 μm) as abrasive was proven to be the most efficient method of cell disruption. The optimum temperature of obtained β-galactosidase was 45 °C and the optimum range pH 6.5–7.5.