Systematic Investigation of the Biocontrol Potential of Bacillus velezensis B05 against Soybean Root Rot Pathogen Fusarium spp.

Soybean is an important global crop, but its production is often limited by root rot, which causes severe yield and quality losses. In this study, a potent antagonistic bacterium, Bacillus velezensis B05, was isolated from the rhizosphere of healthy soybean plants. Genome analysis identified eight biosynthetic gene clusters, including bacilysin and macrolide H, as well as 34 carbohydrate-active enzymes, suggesting its biocontrol potential. Metabolomic analysis detected 621 metabolites, and KEGG enrichment results were consistent with the genomic predictions. The cell-free supernatant of B05 significantly inhibited the growth of Fusarium spp. by 65.85%, spore germination by 75.85%, and disease incidence by 62.5%. Scanning electron microscopy revealed severe damage to fungal cells, including spore deformation and hyphal disintegration. In addition, B05 produced lytic enzymes and siderophores related to plant growth promotion. These results indicate that B. velezensis B05 has potential as a multifunctional biocontrol agent for sustainable management of soybean root rot.