In this study,the regulation of Bifidobacterium bifidum B11 on intestinal mechanical barrier and its antagonistic effect on Enterotoxigenic E.coli(ETEC)were analyzed by combining the in vitro batch fermentation system of intestinal flora with HT-29 cells.And its regulation mechanism on immune barrier was investigated through its effect on macrophages RAW264.7.The results showed that Bifidobacterium bifidum B11 could antag-onize the damage of ETEC to HT-29 under the condition of in vitro fermentation,and increase the relative mRNA expression rate of MUC2,MUC5AC,tight junction protein ZO-2,Claudin-1 and Occudin to 3.78,1.75,4.86,4.06 and 3.29.The relative proliferation rate ofRAW264.7 cells treated with B11 suspension increased by(17.48±2.49)％,the phagocytosis rate increased to(121.63+9.85)％,and the secretion of cytokines IL-12 and TNF-α were promoted(P＜0.05).In conclusion,Bifidobacterium bifidumB11 can strengthen the intestinal mechanicalbarrier and immune barrier,and has the potential to further develop as probiotic.
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