Isolation,Identification And Probiotic Characteristics Of Lactobacillus From Traditional Fermented Dairy Products In Mongolia

In this study,seven traditional dairy products(camel milk,sour horse milk,raw milk,curd,milk curd,butter and cheese)were collected from 14 regions in Mongolia.The aim of this study is to isolate,identify lactic acid bacteria and investigate their probiotic properties.The results are as follows:1.109 LAB strains which isolated from traditional dairy products in 14 regions of Mongolia were preliminarily identified by the morphological characteristics,Gram staining test and catalase contact,then were identified by the 16 S rDNA sequence analysis and carbohydrate fermentation test included 54 Lactobacillus strains belonging to the six species: Lactobacillus plantarum MGL24-4,Lactobacillus brevis MGL22-8,Lactobacillus helveticus MGL1-1,Lactobacillus rhamnosus MGL3-4,Lactobacillus paracasei MGL23-3 and Lactobacillus delbrueckii MGL3-2.2.Probiotic capacity screening was performed in the 54 isolated Lactobacillus representative strains with screening indexes covering acid-bile tolerance ability to survive in the simulated gastrointestinal fluid antimicrobial activity,adhesion ability test,sensitivity against antibiotics,hemolysis test and antibacterial ability test.With the screening,a total of 5 strains with favorable probiotic capacity were founded,including MGL17-1,MGL18-5,MGL25-5,MGL 25-2 and MGL22-5.3.MGL17-1,MGL25-2 and MGL22-5 strains were administered orally to BALB/c mice for 14 days before infection with Salmonella typhimurium.the results showed that the lactic acid bacteria MGL17-1 strain can significantly reduce the liver and colon lesions in mice and have a protective effect against Salmonella typhimurium infection.4.MGL17-1,MGL18-5,MGL25-5,MGL22-5 strains were administered orally to BALB/c mice for 14 days before infection with Staphylococcus aureus.Through observing the body temperature change of mice,Staphylococcus aureus colonization in lung,and the degree of lung pathology,we found that these four lactobacillus strains could significantly reduce the pathological changes and Staphylococcus aureus colonization in the lungs.All of them have certain antagonistic effects against Staphylococcus aureus infection.