Quorum sensing positively regulates CPS-dependent phage infection in .

Unlabelled: Quorum sensing (QS) orchestrates many bacterial behaviors, including virulence and biofilm formation, across bacterial populations. Nevertheless, the underlying mechanism by which QS regulates capsular polysaccharide (CPS)-dependent phage-bacterium interactions remains unclear. In this study, we report that QS upregulates the expression of CPS-dependent phage receptors, thus increasing phage adsorption and infection rates in . We found that QS upregulated the expression of the gene, leading to increased synthesis of phage receptor CPS synthesis in . The signal molecule autoinducer-2 released by from different sources can potentially enhance CPS-dependent phage infections. Therefore, our data suggest that inhibiting QS may reduce, rather than improve, the therapeutic efficacy of CPS-specific phages.

Importance: Phage resistance is a direct threat to phage therapy, and understanding phage-host interactions, especially how bacteria block phage infection, is essential for developing successful phage therapy. In the present study, we demonstrate for the first time that uses quorum sensing (QS) to promote capsular polysaccharide (CPS)-specific phage infection by upregulating expression, which is necessary for the synthesis of phage receptor CPS. Although increased CPS-specific phage susceptibility is a novel trade-off mediated by QS, it results in the upregulation of virulence factors, promoting biofilm development and enhanced capsular polysaccharide production in . This suggests that inhibiting QS may improve the effectiveness of antibiotic treatment, but it may also reduce the efficacy of phage therapy.