Integrated assays with in silico analyses indicated the biocontrol potential of Bacillus velezensis BJ1 against fungal phytopathogens

Fungal diseases continue to devastate global fruit and vegetable production, emphasizing the urgent need for sustainable disease management approaches such as microbial biocontrol. In this study, a locally isolated bacterial strain was identified as Bacillus velezensis BJ1 based on phylogenomic analysis, and its biocontrol potential was evaluated using in vitro , in vivo , and in planta assays combined with in silico analysis. In vitro dual culture assay demonstrated broad-spectrum antagonistic activity of the BJ1 strain against 59 isolates of common fungal phytopathogens affecting fruit trees and vegetables, with inhibition rates ranging from 53.76% to 98.45%. The strongest suppression was observed against Diaporthe sojae OSS① (98.45%), followed by D. sojae B2 JZB320190 (89.15%), Cladosporium cladosporioides TZZG-11-A-S1 (85.37%), C. cladosporioides TZZG-6-A-S1 (85.22%), D. sojae JZB320189 (80.62%), and D. eres TZZG36-S1 (80.62%). Detached tomato leaf assays against the gray mold pathogen Botrytis cinerea demonstrated that BJ1 achieved high control efficiencies of 87.87% and 68.95% for therapeutic and preventive treatments, respectively, at a concentration of 1 × 10⁷ CFU/mL. Furthermore, a BJ1-based water-dispersible granule formulation applied at 2 × 10 8 CFU/mL achieved an 80.48% disease inhibition rate under greenhouse conditions. Genome mining identified 13 biosynthetic gene clusters encoding antimicrobial compounds, suggesting a genetic basis for BJ1’s biocontrol activity. Overall, B. velezensis BJ1 demonstrates strong potential for development as an effective biocontrol product, offering both genomic insights and practical application in sustainable disease management. IMPORTANCE Biological control is a sustainable strategy for managing plant pathogens while reducing the environmental and health risks associated with chemical pesticides. However, their practical application is often limited by poor environmental adaptation, limited broad-spectrum activity, and inconsistent efficacy. Bacillus velezensis BJ1, a locally isolated strain, exhibited broad antagonistic activity against 59 isolates of common phytopathogens across eight host plants. Further, it exhibited consistent in vivo and in planta efficacy against the highly virulent pathogen Botrytis cinerea under both protective and therapeutic treatments, highlighting its potential for both disease prevention and post-infection suppression. Whole-genome phylogenomic analysis confirmed its precise taxonomic identity, and genome mining suggested multiple biosynthetic gene clusters potentially associated with antifungal activity and plant protection. This study highlights BJ1 as a robust and eco-friendly candidate for sustainable disease management.