| Summary: | 碩士 === 國立中興大學 === 食品暨應用生物科技學系所 === 99 === Bifidobacterium strains were well known as a predominant component of the intestinal flora in breast-fed infant feces and breast milk. This bacterial group plays a vital role in modulating host immunity and maintaining the gut health. In this study, the eighteen strains of Bifidobacterium strains which were isolated from infant feces and breast milk were screened for their ability to induce cytokines production by peripheral blood mononuclear cells (hPBMCs). The results indicated that not only different strains but also different species have different effect on the stimulation of all tested cytokines production. Moreover, the results also revealed that capacity of cytokine induction was dose-dependent. B. adolescentis DB-2458 and B. longum subsp. infantis GB-1496 at a concentration ratio 1:30 (hPBMCs: bacterial cells) which were potent inducers for IFN-γ secretion (Th1 cytokine) and induced low level of IL-5 and IL-13 (Th2 cytokines) were viable choices to down regulate Th2 cytokines. B. adolescentis DZN092, B. adolescentis DZN365 (concentration ratio 1:3, 1:0.3), B. adolescentis DB-2458 (concentration ratio 1:30, 1:3) and B. longum HB-762 (concentration ratio 1:30) which strongly induced TNF-α and IL-6 were promoted for the inflammation to initiate the healing process due to the infection. While B. adolescentis DZN092 (concentration ratio 1:30, 1:3, 1:0.3), B. adolescentis DZN365 (concentration ratio 1:30, 1:0.3), B. longum GK - 22 (concentration ratio 1:30) and B. longum GL-78 (concentration ratio 1:0.3) which highly induced both of IL-10 and TGF-β (anti-inflammatory cytokines) releases and induced low level of TNF-α and IL-6 (pro-inflammatory cytokines) could exert immune balance toward anti-inflammatory response. Based on comparison of immunomodulating activity and general criteria tests for probiotic, B. adolescentis DZN092, B. adolescentis DB-2458, B. longum subsp. infantis GB-1496, B. longum HB-762, B. longum GK-22 and B. longum GL-78 were acid and bile resistant strains. They could survive under acidic condition at pH 2-4 and bile condition (0.3% bile salts). For adhesion ability, all of test strains were adhesive strains. In conclusion, the selected strains were viable choices for therapeutic use and could be applied in desirable functional food due to their specific health benefits.
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