Formulation of Bacillus consortium as a biocontrol agent against leaf blight disease in edamame soybean

Edamame ( Glycine max (L.) Merr.) is a soybean variety that has developed as an export commodity in Indonesia. However, its productivity is often constrained by leaf blight disease, which is presumed to be caused by pathogenic bacteria that have not been extensively studied. Edamame disease management has largely relied on pesticide applications, but is restricted due to chemical residue regulations in export products. This study aimed to evaluate the effectiveness of a consortium of three Bacillus species ( B. siamensis ST4, B. amyloliquefaciens LB2, and B. subtilis JB12) formulated in a potato–sugar-based liquid medium supplemented with three types of broths (chicken, fish, and shrimp) as an alternative biocontrol strategy for leaf blight disease. Sequence analysis of the 16S rRNA gene identified the edamame leaf blight pathogen as Pseudomonas aeruginosa . The liquid formulation maintained the viability of Bacillus spp. above 10¹⁰ CFU/mL for up to 63 days of storage and effectively inhibited the growth of P. aeruginosa in vitro, with inhibition levels influenced by the broth type. Field trials demonstrated that the Bacillus spp. consortium formulations with different broths reduced disease incidence (28.3–33.3%), severity (2.87–3.33%), and AUDPC values (21.9–28.9) compared to the control after 65 days of observation. Moreover, these treatments significantly enhanced plant growth and yield. The organic-based liquid formulation exhibits strong potential as an effective, environmentally friendly, and practical biocontrol technology to support sustainable edamame production.