Peptide Hydrolases of Lactobacillus helveticus and Lactobacillus delbrueckii ssp. bulgaricus

摘要: Abstract Lactobacillus helveticus CNRZ 32 had more aminopeptidase and dipeptidase activity than did ATCC 10797 or delbrueckii ssp. bulgaricus 12278, whereas L. was most proteolytic (100%), followed closely by (92%), 12278 (50%). Crude cell-free extracts of the three lactobacilli lacked carboxypeptidase endopeptidase activities. two aminopeptidase-active bands, each only one active band; relative mobility values bands differed among strains. The with different mobilities. Intracellular protease, aminopeptidase, activities increased gradually at beginning log phase reached a maximum stationary phase, but after 24h, enzyme slightly reduced. Freezing cells –96°C holding them that temperature for 1 wk reduced 10% compared those unfrozen cells. freezing process also population viable grown in MRS broth skim milk 50 75%, respectively. Aminopeptidase sterile whey-based medium not vary markedly from broth, 1.5-fold medium. Proteolysis whole required up to 145h, 54h needed extracts. Extracts were proteolytic, completely hydrolyzed α s1 -, β- κ-caseins without preference, an extract completely, partially -casein. β-casein, while -casein resisted hydrolysis. pH end proteolysis below 4.0 10797, above 12278.