Bacillus velezensisHBXN2020 alleviatesSalmonellaTyphimurium infection in mice by improving intestinal barrier integrity and reducing inflammation

Bacillus velezensisis a species ofBacillusthat has been widely investigated because of its broad-spectrum antimicrobial activity. However, most studies onBacillus velezensishave focused on the biocontrol of plant diseases, with few reports on antagonizingSalmonellaTyphimurium infections. In this investigation, it was discovered thatBacillus velezensisHBXN2020, which was isolated from healthy black pigs, possessed strong anti-stress and broad-spectrum antibacterial activity. Importantly,Bacillus velezensisHBXN2020 did not cause any adverse side effects in mice when administered at various doses (1 × 10⁷, 1 × 10⁸, and 1 × 10⁹CFU) for 14 d. SupplementingBacillus velezensisHBXN2020 spores, either as a curative or preventive measure, dramatically reduced the levels ofSalmonellaTyphimurium ATCC14028 in the mice’s feces, ileum, cecum, and colon, as well as the disease activity index (DAI), in a model of infection caused by this pathogen in mice. Additionally, supplementingBacillus velezensisHBXN2020 spores significantly regulated cytokine levels (TNF-α, IL-1β, IL-6, and IL-10) and maintained the expression of tight junction proteins and mucin protein. Most importantly, addingBacillus velezensisHBXN2020 spores to the colonic microbiota improved its stability and increased the amount of beneficial bacteria (LactobacillusandAkkermansia). All together,Bacillus velezensisHBXN2020 can improve intestinal microbiota stability and barrier integrity and reduce inflammation to help treat infection bySalmonellaTyphimurium.