Abstract
Background: Mastitis, one of the most serious diseases in dairy industry, could cause tremendous economic losses worldwide and is commonly trigged by pathogen invasion. Staphylococcus aureus (S. aureus) -induced mastitis has been reported to play an important role in mastitis etiology characterized by high morbidity, recurrence, and increased antibiotic resistance, which may attribute to the formation of biofilm formation, a form of bacterial aggregation for better growth and resistance to adverse conditions. Probiotics Bacillus has been reported to disrupt bacteria quorum-sensing (QS) system, a central regulator for biofilm formation. However, whether commensal Bacillus affects S. aureus biofilm formation and consequent colonization during mastitis is still unknown. Results：Here, we identified that the Bacillus is associated with reduced colonization of S. aureus in the mammary gland of cows. Interestingly, Bacillus did not affect S. aureus growth but inhibited the biofilm formation of S. aureus by interfering with S. aureus QS signaling. The most obvious anti-biofilm effect was found in Bacillus subtilis H28, so it was selected for further study. We found that bacillus subtilis H28 treatment alleviated S. aureus-induced mastitis in mice, as showed by limiting pro-inflammatory cytokines production, enhancing barrier integrity, and reducing S. aureus burden. Consistently, Bacillus subtilis with the capacity to interfere S. aureus QS ameliorated S. aureus-induced NF-κB activation in mice mammary epithelial cells（MMECs）. Conclusions: Collectively, our results indicate that commensal Bacillus inhibits S. aureus colonization and alleviates S. aureus-induced mastitis by influencing biofilm formation, which suggests a potential strategy for the decolonization of S. aureus and acts as a basis for the prevention and treatment of S. aureus-related disease.
Enterotoxins production, biofilm formation and antimicrobial resistance of Staphylococcus aureus strains isolated from refrigerated raw cow milk