Abstract: Potato common scab, a severe soilborne disease caused by Streptomyces scabies, has become increasingly prevalent in major potato-producing regions in China, causing significant yield and quality losses. However, effective and environmentally friendly control strategies remain limited. In this study, a biocontrol strain, ZF517, exhibiting strong antagonistic activity against S. scabies, was isolated. Based on morphological characteristics, physiological and biochemical tests, and multi-gene phylogenetic analysis, ZF517 was identified as Bacillus subtilis. Antagonistic spectrum analysis revealed that ZF517 exhibited potent inhibitory effects against six pathogenic fungi and three pathogenic bacteria. Biocontrol-related traits analysis showed that ZF517 secretes proteases and siderophores and harbours biosynthetic genes for Surfactin, Macrolactin, Fengycin, Difficidin, Bacillibactin, Bacillaene, Bacilysin, and Iturin. Moreover, the fermentation broth of ZF517 significantly inhibited the mycelial growth of S. scabies. A radish seedling assay confirmed that the fermentation broth effectively suppressed S. scabies infection, achieving a biocontrol efficacy of 63.94%. In pot experiments, ZF517 exhibited a biocontrol efficacy of 58.07% against potato common scab, significantly surpassing the efficacy of the chemical control treatment (20% thiazole zinc suspension concentrate). These findings indicate that ZF517 holds great potential as a biocontrol agent for managing potato common scab.

Key words: Bacillus subtilis, potato common scab, lipopeptides, biological control