植物乳杆菌ST-Ⅲ蛋白酶活性的研究

Study on the Protease Activity of Lactobacillus plantarum ST-Ⅲ

植物乳杆菌ST-Ⅲ(Lb.plantarum ST-III)是一株具有降低血清胆固醇能力的益生菌,其在脱脂乳中生长缓慢,产酸能力弱。实验选取一株凝乳性较好的植物乳杆菌CZ2112作为参照,对植物乳杆菌ST-Ⅲ蛋白酶活性进行研究。植物乳杆菌ST-Ⅲ蛋白酶活性及蛋白水解能力比植物乳杆菌CZ2112低,而氨肽酶和羧肽酶活性与之差异较少,推测得出植物乳杆菌ST-III在脱脂乳中不能很好生长和凝乳的原因是该菌株蛋白酶活性较低,生长初期不能很好利用外源蛋白质营养。在添加鱼蛋白胨等促进生长后,植物乳杆菌ST-Ⅲ可以将蛋白质、多肽水解成一系列的寡肽或氨基酸,满足菌体生长的氮素营养。

Lactobacillus plantarum ST-Ⅲ,a prohioties with ability to remove vivo, demonstrated weak ability to grow in skim milk and to clot milk by the impacts of the proteolytic activity of Lb. plantarum ST-Ⅲ on the growth cholesterol in vitro and in acidification. To illustrate of itself the extraeellular protease and intracellular peptidase activity of Lb. plantarum ST-Ⅲ were compared with Lb. plantarumCZ 2112, a strain growing well in skim milk supplemented with glucose and elotting milk proteins rapidly. Compared with Lb. plantarum CZ 2112, Lb. plantarum ST-Ⅲ had lower protease activity, whereas there was no obvious differenee in the activity of aminopeptidase and carhoxypeptidase activities between the two Lactobacillus strains. Therefore, it was presumed that deficiency inprotease activity of tides Lb. plantarum ST-Ⅲ, which was responsible for hydrolyzing large milk proteins into small peptides when the bacteria were cultivated in skim milk, was correlated with the poor ability of Lb. plantarum ST-Ⅲ to grow in and clot milk.