Exploring the Panax ginseng Meyer soil metagenome to uncover antagonistic bacteria against ginseng root rot disease.

Background: Ginseng, renowned for its health benefits, is often cultivated with pesticides, which contradicts its health-enhancing properties. To address this, we identified Bacillus velezensis ARRI17 through a 5-year monitoring of ginseng yield on a national scale and comparative metagenome analysis. ARRI17 is a biocontrol agent that enhances ginseng growth and disease resistance under authentic field conditions. Methods: We identified ARRI17 through metagenomic analysis of soil samples collected from ginseng fields classified as high-yield (3.54 ± 0.46 kg per 1.62 m2) or low-yield (0.9 ± 0.21 kg per 1.62 m2), based on comparisons to the national 5-year average yield of 2.13 ± 0.35 kg per 1.62 m2. The biocontrol efficacy of ARRI17 was validated under laboratory conditions and field trials. Additionally, we analyzed the genomic and physiological characteristics of ARRI17 to clarify its antifungal mechanisms and adaptability to diverse environments. Results: ARRI17 exhibited strong inhibitory activity against multiple ginseng fungal pathogens, including Ilyonectria mors-panacis, in both controlled and field conditions. The application of ARRI17 improved ginseng growth parameters and reduced disease incidence in infested soil. Genomic analysis revealed that ARRI17 produces antimicrobial compounds, such as Iturin A, confirmed by HPLC. Furthermore, ARRI17 naturally thrived in rice straw compost, a traditional biofertilizer used in ginseng cultivation, suggesting its long-term presence and compatibility with standard ginseng farming practices. Conclusion: Bacillus velezensis ARRI17 is an effective biocontrol agent that promotes ginseng growth and enhances disease resistance. Its natural compatibility with traditional farming practices, especially its presence with rice straw compost, positions ARRI17 as a promising and sustainable alternative.