Protective Effects of <i>Bacillus subtilis</i> HH2 against Oral Enterotoxigenic <i>Escherichia coli</i> in Beagles

Abstract

This study evaluated the protective effect of Bacillus subtilis HH2 on beagles orally challenged with enterotoxigenic Escherichia coli (ETEC). We assessed the physiological parameters and the severity of diarrhea, as well as the changes in three serum immunoglobulins (IgG, IgA, and IgM), plasma diamine oxidase (DAO), D-lactate (D-LA), and the fecal microbiome. Feeding B. subtilis HH2 significantly reduced the severity of diarrhea after the ETEC challenge (p p B. subtilis HH2 administration also reduced serum levels of DAO at 48 h after the ETEC challenge (p p > 0.05). Oral ETEC challenge significantly reduced the richness and diversity of gut microbiota in beagles not pre-fed with B. subtilis HH2 (p B. subtilis HH2 feeding and oral ETEC challenge significantly altered the gut microbiota structure of beagles (p B. subtilis HH2 feeding reduced the relative abundance of Deinococcus-Thermus in feces. This study reveals that B. subtilis HH2 alleviates diarrhea caused by ETEC, enhances non-specific immunity, reduces ETEC-induced damage to the intestinal mucosa, and regulates gut microbiota composition.

Keywords

• <i>Bacillus subtilis</i>
• enterotoxigenic <i>Escherichia coli</i>
• gut microbiome
• intestinal barrier
• probiotic
• beagles