Hydrolysis of casein by intracellular proteases from lactic acid bacteria.

Intracellular proteases (IPLB's) from Streptococcus cremoris, Sir. lactis, Lactobacillus bulgaricus and L. helveticus were prepared and their proteolytic properties against whole casein from three sources and also against casein fractions were studied at 30°C, pH 7.0. β-Casein was hydrolyzed more easily than αs-casein by each IPLB. These findings were also derived from the patterns of the agar-gel electrophoresis of the hydrolysis products of casein-I which were obtained with each IPLB. K-Casein prepared from either casein-I or-II was more easily hydrolyzed than β-casein by each IPLB.