Trait-based engineering of a stress-resilient Bacillus subtilis consortium toward scalable biocontrol of fusarium-induced plant diseases

Fusarium-induced diseases pose a critical threat to global food security, driving yield losses and mycotoxin contamination, where reliance on chemical fungicides is undermined by ecological risks and microbial biocontrol is hindered by inadequate resilience under abiotic stress. In this study, a stepwise strategy was employed to design a stress-resilient Bacillus subtilis consortium with integrated antagonistic and adaptive traits. From an initial pool of 104 indigenous isolates, elite candidates were identified through comparative antagonism assays and functional trait profiling. Subsequent screening under multiple abiotic stresses including salinity, drought, pH extremes, heat and UV irradiation enabled the selection of highly resilient strains (A: gl, B: Kb, C: gb and D: A15d). Eleven consortia manifested synergistic gains in antifungal potency and abiotic stress resilience, with principal component analysis identifying consortium AB as the most promising formulation, integrating broad-spectrum Fusarium suppression with superior environmental robustness. Subsequent process optimization of AB consortium through Plackett–Burman and response surface methodology pinpointed glucose, yeast extract and brewer’s spent grain as critical drivers of biomass accumulation and sporulation. The optimized formulation yielded up to 11-fold higher biomass and a 6.7-fold increase in sporulation, indicating the potential for cost-effective production through the valorization of agro-industrial residues. Collectively, this study establishes stress-resilient B. subtilis consortia as a promising and environmentally sound bioformulation, with potential application in integrated Fusarium disease management, warranting further validation under plant-based and field-relevant conditions.