Effects of Mixed Probiotic Spores of Bacillus Coagulans and Bacillus Subtilis on Gut Microbiota and Intestinal and Liver Damage of Rats Infected with Salmonella Typhimurium

Background: Although the intestinal lumen is a major way for the entrance of pathogens such as Salmonella, they face a dense microbiota in the gut lumen. This community confers health benefits. The probiotics enhance the colonization resistance and direct inhibitory effects against pathogens, which are important in reducing the incidence, duration of gastroenteritis and also histopathological effects. Methods: In this study spore of two probiotic bacteria, Bacillus subtilis and Bacillus coagulans were fed to rats for three weeks through their daily water intake after which Salmonella Typhimurium was gavaged to the rats. On days 1, 3, 5 and 7 after gavaging, intestinal microbiota and days 1, 3, 5 and 7 after gavaging, gut and liver histopathological changes were evaluated. Results: In comparison to the control group, Salmonella caused no change in spore and aerobic bacteria population but it caused anaerobic and coliform bacteria increase and LAB reduction. But B. subtilis and B. coagulans accompaniment with salmonella reduced the anaerobe and coliform bacteria and decreased the LAB population following Salmonella infection. Also, the histopathological evaluation showed that these probiotic attenuated shortening and fusion of villi, mononuclear cells infiltration, submucosal edema and epithelial necrosis in the intestine, hepatocyte degeneration and mononuclear cells infiltration in the liver which occurred due to Salmonella infection.Conclusion: B. subtilis and B. coagulans help the maintenance of the gut microflora population and reduce the histopathological effects when exposing to the Salmonella, which, causes the reduction of this pathogen effects and early recovery.