Studies On Biological Properties And Probiotic Effects Of Lactobacilli From Traditional Dairy Products In Inner Mongolia

To establish foundation for exploitation and utilization of lactobacillus resource and to provide strains and principle knowledge for utilizing of beneficial lactobacilli in functional food and microbial ecological agents, Lactobacillus strains which were isolated from traditional dairy products in Inner Mongolia were studied systematically and comprehensively from the following several aspects: isolation and identification of strains, studies on biological properties, in vitro screening of potential probiotics, as well as in vivo investigation and verifying of physiological function. The following results were gained:1. 53 strains of Lactobacillus were isolated from 98 samples. They were homoferme- ntative except 1 strain. They belonged to 30 strains L. plantarum,5 strains L. casei,5 strains L. helveticus,3 strains L. coryniformis subsp. coryniformis,3 strains L. curvatus,2 strains L. zeae,1 strains L. agilis, 1 strains L. murinus, 1 strains L. farciminis,respectively. 2 strains were unidentified to species. Most strains could grow in a wider temperature scope. No matter which districts they were isolated from, the predominant strain was L. plantarum.2. Among the 53 strains lactobacilli, there were 12 strains lactobacilli whose growth rate in MRS medium supplemented with 0.3% sodium taurocholate and survival rate in pH3 condition was more than 30% and 60% respectively, and all of them were L. plantarum; Their adherent rate to colon adenocarcinoma cell line HT-29 was between 1.90 bacteria/cell～3.45 bacteria/cell; Most strains had a wide antimicrobial activity to pathogenic bacteria, e.g Staphylococcus aureus, Shigella flexneri, et al. The antimicrobial activity was weak to nonpathogenic bacteria. The antimicrobial substance was mainly organic acid. L. plantarum WH24-2-4 could produce bacteriocin-like antimicrobial substance; 12 strains L. plantarum were all susceptible to piperacillin,amoxicillin/clavulanic acid, cefazolin, clindamycin, sulfamethoxazole/timethoprim, rifampin and nitrofurantoin, moderately susceptible to cefoperazone and acetylspiramycin, susceptible or moderately susceptible to azithromycin and neomycin, and resistant to a group of 5 antibiotics, which included penicillin G, vancomycin, norfloxacin, ofloxacin and ciprofloxacin. Most strains were susceptible to ampicillin, susceptible or moderately susceptible to cefotaxime, and resistant to polymycin B. L. plantarumWH13-1,WH24-1-2 and WH23-1 had no plasmid, but L. plantarum WZ32-2-1,WH24-2-3,WH15-3 and WZ47-1 contained the plasmids whose molecular weight was above 19kb.3. All of 12 strains L. plantarum tested could remove cholesterol from growth media and deconjugate sodium taurocholate. The removal rate was between 25.5%～43.1%, and there...