Abstract:

Grape anthracnose, caused by Colletotrichum gloeosporioides, is one of the most serious diseases affecting grape production. Biological control has emerged as a key strategy for managing this pathogen. Bacillus subtilis BS-1 exhibits strong antagonistic activity against C. gloeosporioides. To elucidate its mode of action and evaluate its field performance, we assessed the inhibitory effects of BS-1 on the mycelial growth and spore morphology of C. gloeosporioides, quantified chitinase and β-1,3-glucanase activities in its fermentation broth, and conducted field trials against grape anthracnose. The results demonstrated that strain BS-1 strongly inhibits C. gloeosporioides, producing an inhibition zone of 10.1 mm. The fungal pathogen failed to grow normally in BS-1 fermentation broth, with spores showing constriction and hyphae exhibiting swelling and abnormal morphology. Biochemical assays confirmed that BS-1 secretes chitinase and β-1,3-glucanase during fermentation. These findings indicate that the antifungal mechanism involves degradation of the pathogen cell wall by these enzymes, leading to growth inhibition. In field trials, the fermentation broth of BS-1 provided effective control of grape anthracnose, with an average efficacy ranging from 64.17% to 75.04%. In conclusion, B. subtilis BS-1 demonstrates strong potential for development as a biocontrol agent against grape anthracnose.

Key words: Colletotrichum gloeosporioides, Bacillus subtilis BS-1, biological control, inhibitory activity, antimicrobial mechanism, chitinase, β-1,3-glucanase, control efficacy evaluation