Enterotoxigenic Escherichia coli (ETEC) disrupts the intestinal barrier's integrity, leading to severe diarrhea and death in newborns and young animals. Bacillus subtilis (B. subtilis), a spore-forming probiotic widely distributed in soil and organic substrates, offers multiple physiological benefits, including enhanced nutrient absorption, antioxidant activity, and intestinal mucosal repair. However, its efficacy in treating ETEC-associated diarrhea in rabbits is not well understood. This study explored the protective role of B. subtilis and its mechanisms in ETEC-challenged rabbits, focusing on inflammatory responses, intestinal barrier integrity, and microbiota composition. We randomly assigned twenty New Zealand white rabbits to four experimental groups: (1) Control group (CON): saline gavage, (2) Model group (ETEC): ETEC + saline, (3) Norfloxacin group (NOR): ETEC + 0.2 mL/kg/d norfloxacin, and (4) the B. subtilis group (BS): ETEC + 1×10⁹ CFU/mL B. subtilis daily. The results showed that B. subtilis intervention alleviated ETEC-induced weight loss and improved colonic pathological damage in rabbits. Moreover, B. subtilis was found to impede the induction of the NF-κB signaling pathway and to diminish the concentrations of IL-1, IL-6, and TNF-α. Additionally, it was observed that B. subtilis increased the expression of tight junction proteins and reduced the abundance of harmful bacteria, such as Proteobacteria. In summary, B. subtilis alleviates ETEC-induced intestinal dysfunction as evidenced by regulating inflammatory responses, maintaining intestinal barrier integrity and modulating the intestinal microbiota.

To Cite This Article: Cheng X, Wang Y, Tang J, Tan H, Ji Y, Wang J, Hu J, Yu X, Zhang S, Fan and Zhao Y, 2025. Bacillus subtilis ameliorates escherichia coli -induced diarrhea in young rabbits through suppression of intestinal inflammation and remodeling of the gut microbiota. Pak Vet J. http://dx.doi.org/10.29261/pakvetj/2025.303