Isolation and characterization of the novel lytic Bacillus subtilis phage vB_Bsu_W1188 revealing a wall teichoic acid glycosylation-dependent resistance mechanism.

Bacillus subtilis is a key starter culture in food fermentation, but phage contamination threatens production stability. As fermentation processes scale up, the risk of phage contamination rises significantly, driving the need for fundamental research on phage-host interactions to develop targeted mitigation strategies. In this study, we isolated and characterized a novel lytic phage, vB_Bsu_W1188, which efficiently lyses B. subtilis WB800. Transmission electron microscopy revealed a short-tailed morphology, while stability tests demonstrated remarkable tolerance to pH 3-12, temperatures of 4-80℃, and even 90℃ for 30 minutes. Genomic and phylogenetic analysis classified it within the genus Beecentumtrevirus, with no virulence or antibiotic resistance genes detected. Through resistance mutant screening and functional validation, we identified that wall teichoic acid (WTA) glycosylation, mediated by the host tagE and galU genes, serves as the critical receptor for phage recognition. Although phage-resistant mutants exhibited fitness costs (e.g., delayed growth and impaired biofilm formation), their mCherry protein expression capacity remained unaffected. This study not only highlights the potential of vB_Bsu_W1188 as a biocontrol agent but, more importantly, elucidates the molecular basis of phage resistance, providing a theoretical foundation and technical support for engineering industrial phage-resistant strains.