Antagonistic activity of selenium-enriched Bifidobacterium breve against Clostridioides difficile

Probiotics have the potential to be used in the prevention of Clostridioides difficile infection (CDI). In this study, selenium (Se)-enriched Bifidobacterium breve YH68-Se was obtained under optimal culture conditions with single-factor and response surface optimization. The overall environmental resistance of YH68-Se was superior to that of the parental strain YH68, mainly reflected in the substantial improvement of antioxidant activity and gastrointestinal tolerance. YH68-Se dramatically inhibited C. difficile growth, spore, biofilm, toxin production, and virulence gene expression, rapidly disrupted C. difficile cell membrane permeability and integrity, and altered the membrane proton motive force (PMF), induced a large outflow of intracellular substances and eventually caused bacterial death. The main factor inducing this process originated from the lactic acid (LD) in YH68-Se. In addition, the LD production of YH68 increased with increasing selenite concentration and was accompanied by enhanced activities of thioredoxin reductase (TrxR), glutathione peroxidase (GSH-Px), and increased concentration of autoinducer-2 (AI-2), which may be the crucial factors contributing to the outstanding probiotic properties of YH68-Se and their potent antagonism of C. difficile.

Automated summary

This study discovered that selenium-enriched Bifidobacterium breve YH68-Se has the potential to prevent Clostridioides difficile infection. YH68-Se exhibited superior environmental resistance compared to the parental strain YH68, mainly due to the improved antioxidant activity and gastrointestinal tolerance. YH68-Se inhibited C. difficile growth, spore, biofilm, toxin production, and virulence gene expression through disrupting cell membrane permeability and altering the membrane proton motive force.