Abstract:[Background] Sorghum serves as a crucial raw material for China's brewing industry. However, during harvest and storage, it is susceptible to infections by Alternaria, Fusarium, Curvularia, and Aspergillus, which lead to mold growth and mycotoxin contamination. These issues severely compromise the quality of brewing products and pose food safety risks. While chemical control methods may cause environmental pollution, biocontrol has emerged as a research hotspot due to its eco-friendly characteristics. [Objective] To screen the microbial strains exhibiting antagonistic effects against fungi infecting brewing sorghum, providing candidate strains for biocontrol agent development. Additionally, it sought to establish a theoretical foundation for improving China's brewing sorghum storage and fungal control systems. [Methods] Taking Alternaria destruens GN3, Fusarium equiseti GN5, Aspergillus chevalieri GN11, Curvularia pseudointermedia GN19, and Candida parapsilosis GN10 as indicator strains and using the plate confrontation method, we isolated the antagonistic strain MY1 and further identified this strain based on its morphological features, physiological and biochemical properties, and molecular evidence. The inhibitory activity of the sterile fermentation filtrate of this strain was assessed via the agar well diffusion assay, while that of volatile metabolites was evaluated via the double-plate confrontation method. Additionally, extracellular hydrolase production was detected. [Results] Strain MY1 exhibited significant inhibitory effects on all the five tested fungal strains, with the inhibition rates exceeding 50.00%. It was identified as Bacillus velezensis. The sterile fermentation filtrate inhibited the growth of A. destruens GN3 at a low concentration of 0.8%, causing abnormal mycelial morphology and achieving an inhibition rate of 53.95%. Furthermore, MY1 demonstrated protease and cellulase secretion capabilities and produced volatile antifungal compounds, displaying broad-spectrum inhibitory activity against multiple pathogenic fungi. [Conclusion] The antagonistic strain MY1 shows remarkable inhibitory activity against fungi infecting brewing sorghum and holds potential as a biocontrol agent for fungal contamination management.
