Next-generation prebiotic promotes selective growth of bifidobacteria, suppressing <i>Clostridioides difficile</i>

Abstract

Certain existing prebiotics meant to facilitate the growth of beneficial bacteria in the intestine also promote the growth of other prominent bacteria. Therefore, the growth-promoting effects of β-galactosides on intestinal bacteria were analyzed. Galactosyl-β1,4-l-rhamnose (Gal-β1,4-Rha) selectively promoted the growth of <i>Bifidobacterium. Bifidobacterium longum</i> subsp. <i>longum</i> 105-A (JCM 31944) has multiple solute-binding proteins belonging to ATP-binding cassette transporters for sugars. Each strain in the library of 11 <i>B. longum</i> subsp. <i>longum</i> mutants, in which each gene of the solute-binding protein was disrupted, was cultured in a medium containing Gal-β1,4-Rha as the sole carbon source, and only the BL105A_0502 gene-disruption mutant showed delayed and reduced growth compared to the wild-type strain. BL105A_0502 homolog is highly conserved in bifidobacteria. In a Gal-β1,4-Rha-containing medium, <i>Bifidobacterium longum</i> subsp. <i>infantis</i> JCM 1222^T, which possesses BLIJ_2090, a homologous protein to BL105A_0502, suppressed the growth of enteric pathogen <i>Clostridioides difficile</i>, whereas the BLIJ_2090 gene-disrupted mutant did not. <i>In vivo</i>, administration of <i>B. infantis</i> and Gal-β1,4-Rha alleviated <i>C. difficile</i> infection-related weight loss in mice. We have successfully screened Gal-β1,4-Rha as a next-generation prebiotic candidate that specifically promotes the growth of beneficial bacteria without promoting the growth of prominent bacteria and pathogens.