This study showed that B. vulgatus Bv46 had a protective effect against DSS-induced mouse colitis by regulating gut microbiota and the contents of SCFAs, inhibiting the expression of colonic proinflammatory cytokines TNF-α, IL-6 and IL-1β and downregulating the expression of Ccl19, Cd19, Cd22, Cd40 and Cxcr5 genes. This evidence concerns the gene CD40 and colitis.