Bacillus amyloliquefaciens TL106 protects mice against enterohaemorrhagic Escherichia coli O157:H7‐induced intestinal disease through improving immune response, intestinal barrier function and gut microbiota

Abstract

Aims This study evaluated the effects of Bacillus amyloliquefaciens (B. amyloliquefaciens) TL106 isolated from Tibetan pigs’ feces, on the growth performance, immune response, intestinal barrier function, morphology of jejunum, cecum and colon, and gut microbiota in the mice with enterohemorrhagic Escherichia coli (EHEC)‐induced intestinal diseases. Methods and Results Forty female C57BL/6J mice were randomly divided into four groups: mice fed a normal diet (Control), mice oral administration of TL106 daily (Ba), mice challenged with EHEC O157:H7 on day 15 (O157), mice oral administration of TL106 daily and challenged with EHEC O157:H7 on day 15 (Ba + O157). The TL106 was administrated to mice for 14 days, and mice were infected with O157:H7 at day 15. We found that TL106 could prevent the weight loss caused by O157:H7 infection and alleviated the associated increase of pro‐inflammatory factors (TNF‐α, IL‐1β, IL‐6 and IL‐8) and decrease of anti‐inflammatory factor (IL‐10) in serum and intestinal tissues of mice caused by O157:H7 infection (P < 0.05). Additionally, TL106 could prevent disruption of gut morphology caused by O157:H7 infection, and alleviate the associated decrease in expression of tight junction proteins (ZO‐1, occludin and claudin‐1) in jejunum and colon (P < 0.05). In cecum and colon, the alpha diversity for bacterial community analysis of Chao and ACE index in Ba + O157 group were higher than O157 group. The TL106 stabilized gut microbiota disturbed by O157:H7, including increasing Lachnospiraceae, Prevotellaceae, Muribaculaceae and Akkermansiaceae, reducing Lactobacillaceae. Conclusions We indicated the B. amyloliquefaciens TL106 can effectively protected mice against EHEC O157:H7 infection by relieving inflammation, improving intestinal barrier function, and mitigating permeability disruption, and stabilizing the gut microbiota. Significance and Impact of the Study B. amyloliquefaciens TL106 can prevent and treat intestinal disease induced by EHEC O157:H7 in mice, which may be a promising probiotic for disease prevention in animals.