Comparison of Beta-Galactosidase Activity of Yeast and Lactic Acid Bacteria after Separate and Co-Culture

The influence of mechanical and physical methods of cell disruption on the activity of beta-galactosidases produced by lactose-fermenting yeast and lactic acid bacteria after separate and co-cultivation in whey permeate was studied. It was found that ultrasound and heat treatment are the most effective methods that allow obtaining the enzyme with significantly higher activity than after quartz sand and glass bead mealing. The beta-galactosidases received as result of co-cultivation of some yeast strains and viscous strains of lactic acid bacteria had activity higher than beta-galactosidases from individual producers. The highest lactase activity (0.8–0.9 IU/ cm3) was obtained using heat treatment and the viscous strain of Lactobacillus acidophilus in combination with the yeasts Kluyveromyces marxianus Y-1338 and Kluyveromyces lactis Y-1333.