Effects of Clostridium butyricum on intestinal environment and gut microbiome under Salmonella infection

Salmonellosis causes massive economic losses globally every year. Especially in poultry, numerous drug-resistant bacteria have emerged; thus, it is imperative to find alternatives to antibiotics. As a probiotic, Clostridium butyricum (C. butyricum) provides the latest strategy for inhibiting the proliferation of Salmonella. This study aimed to evaluate the effects of C. butyricum on intestinal environment and gut microbiome under Salmonella infection. In this study, we modeled the infection of Salmonella using specific pathogen-free (SPF) chicks and found that the use of C. butyricum directly reduced the number of Salmonella colonizations in the spleen and liver. It also alleviated the histopathological changes of the liver, spleen, and cecum caused by Salmonella Enteritidis (S. Enteritidis). In addition, S. Enteritidis increased the expression of pro-inflammatory IL-6 in the cecum on day 6 postinfection. Interestingly, we found that C. butyricum changed PPAR-γ transcript levels in the cecum on day 6 postinfection. Analysis of the chick gastrointestinal microbiome showed that Salmonella infection increased the relative abundance of Subdoligranulum variabile. Further analysis found that Salmonella challenge significantly reduced the relative abundance of Faecalibacterium prausnitzii and C. butyricum increased the relative abundance of anaerobic bacteria in the gut on day 6 postinfection. Moreover, early supplementation of C. butyricum restored the epithelial hypoxia in S. Enteritidis infection in chicks. The results suggest that C. butyricum restores epithelial hypoxia caused by S. Enteritidis, improves the stability of intestinal flora, and inhibits the proliferation of Salmonella.