The biocontrol potential of volatile organic compounds produced by Bacillus subtilis KRS015 against plant pathogenic fungi Botrytis cinerea

A vast array of bacteria inhabit nature, many of which inhibit the growth of other microorganisms by secreting a diversity of metabolic products. Leveraging this unique trait, researchers have applied these bacteria to the prevention and control of plant diseases. In this study, Bacillus subtilis KRS015 exhibited a broad-spectrum antifungal activity, and was proved to prevent the occurrence of gray mold disease caused by Botrytis cinerea on Kyoho grapes. The volatile organic compounds (VOCs) released by strain KRS015 interfered with the organelles of B. cinerea , resulting in cellular structural damage and significantly reducing the expression of melanin synthesis related gene Bcscd1 . The composition of VOCs was analyzed using GC-MS and EC ₅₀ value was determined respectively. Isobutyric acid was identified as the most effective antagonistic compounds, which was able to completely inhabit the growth of B. cinerea at a concentration of 79.46 µmol L ^− 1 . Especially, the VOCs produced by strain KRS015 significantly inhibited the growth of B. cinerea on grapes, on day 4, the decay incidence of the grapes was 98% in the control group compared to 54% in the treatment group, in addition, VOCs enhance various enzyme activities of SOD and PPO in Kyoho grapes. Notably, EC ₅₀ and EC ₁₀₀ of isobutyric acid also effectively inhibited the growth of pathogenic fungi without adversely affecting grape quality or enzymatic activity. These results suggested that B. subtilis KRS015 has potential as a biological control agent (BCA) for postharvest disease management.