| Summary: | 碩士 === 中興大學 === 食品暨應用生物科技學系 === 95 === Due to the probiotic properties and their utilization in fermented food processing, lactic acid bacteria (LAB) strains have been the major research interest. Recently, the physiological effects on human and the use in health food preparation for lactic acid bacteria have been paid with attention. In this study, the isolation and characterization of microorganisms from different sourse was investigated. In addition, we further studied the probiotics potential; modulate immune response and anti-invasion activities of these isolated lactic acid bacteria. It was found that some LAB strains were tolerant to the acidity of pH2.0 phosphate buffer, and a small number of strains were also resistant to 0.3% bile salt. For the adhesive ability study, some LAB strains were found to be able to adhere to Int-407 cell line. Furthermore, the effect of LAB on S. typhimurium invasion to the Int-407 cells was also studied. It was found that the spen culture supernatant of Lactobacillus acidophilus LAP5+ L. plantarum LPR1+ L. salivarius BY3 could reduce the invasion of S. typhimurium into the Int-407 cells. The protective effect by orally administered differet mix-LAB on the invasion of S. typhimurium cells to the soleen and liver organs of mice was investigated. Result showed that the cell number of S. typhimurium in liver and spleen organs of mice was lower for mice administered with mix-LAB strains Lactobacillus acidophilus LAP5+ L. plantarum LPR1+ L. salivarius BY3 and heat-killed Lactobacillus acidophilus LAP5+ L. acidophilus LAY5+ L. acidophilus LAH7 as compared to those administered with saline. Finally,to study the effect of LAB strains on the immune system, it was found that LAB can improve the mice primary cell culture activation and high leve of immunoglobulin IgA. In this study, we demonstrated that lactic acid bacteria could stimulate immune response and reduced the infected pathogens based on animal model.
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