Table 1_Integrated multi-omics and phenotypic validations reveal biocontrol mechanisms of Bacillus velezensis XM18-5 against potato common scab.xlsx

Potato common scab, caused by pathogenic Streptomyces species, is a devastating soil-borne disease that severely compromises potato yield and marketability. To develop effective biological control strategies and elucidate their molecular mechanisms, this study isolated a potent antagonistic strain, XM18-5, from disease-suppressive soil. Through a systematic approach integrating phenotypic assays, whole-genome sequencing, and non-targeted metabolomics, the strain was identified as Bacillus velezensis. In vitro assays demonstrated that XM18-5 exhibits significant antagonistic activity against Streptomyces scabies X-1 (60.72% inhibition rate), causing severe hyphal deformation and lysis as revealed by scanning electron microscopy. In pot experiments, XM18-5 treatment achieved a biocontrol efficacy of 70.90% against potato common scab and displayed broad-spectrum antifungal activity against ten other plant pathogens. Genome mining uncovered 12 biosynthetic gene clusters (BGCs) encoding diverse antimicrobial compounds, including surfactin, fengycin, and difficidin. Crucially, metabolomic analysis of the fermentation broth at the stationary phase provided direct material evidence for this genetic potential, identifying a specific chemical cocktail containing the lipopeptide Surfactin, the dipeptide antibiotic Bacilysin, and broad-spectrum antibiotics such as Erythromycin. Furthermore, metabolic pathway analysis revealed a significant upregulation of amino acid biosynthesis (e.g., valine, leucine, and phenylalanine), ensuring a robust precursor supply for these antimicrobial secondary metabolites. In conclusion, B. velezensis XM18-5 suppresses potato common scab through a synergistic mechanism driven by a genome-encoded, metabolically supported arsenal of antimicrobial compounds. This study provides a comprehensive understanding of the biocontrol mechanisms of XM18-5, establishing it as a promising candidate for bio-fertilizer development.