| Congresso Brasileiro de Microbiologia 2023 | Resumo: 1057-2 | ||||
Resumo: Sclerotinia sclerotiorum is a necrotrophic fungus that causes white mold disease in several economically important crops, such as soybeans, beans and canola. This fungus produces sclerotia, which are resistance structures that remain latent in the soil for up to 10 years until they find favorable conditions of temperature and humidity to germinate. Sclerotia make the control of the disease difficult, and the most commonly used control method is the application of chemical fungicides. As an alternative, there is biological control, which uses microorganisms or metabolites produced by them to control the disease. Cave bacteria can be interesting microorganisms for biological control since caves are limiting environments and still little explored, and new products with antifungal potential can be produced. In this study, the bacteria isolated from caves, Bacillus sp. CMA12, in the mycelial control of S. sclerotiorum and sclerotia by direct confrontation. This technique consists of a 5 mm disc containing mycelium of the fungus inoculated at the end of a petri dish containing Mueller Hinton culture medium, and at the opposite end, 25 µL of Bacillus sp. CMA12. In the center of another plate, sterile sclerotia submerged in Bacillus sp. CMA 12, were inoculated, and the plates were incubated for 7 days at 20 °C. After this period, the formation of inhibition halos was observed in the confrontation plates between the mycelium of S. sclerotiorum and Bacillus sp. CMA 12 (Fig. 1 - A). In the plates containing the sclerotia, which were submerged in bacterial culture, it was not possible to observe germination and mycelium formation. In the control plates, where there were sterile sclerotia, they germinated and formed mycelium (Fig. 1 - B).
Most likely, Bacillus sp. CMA 12 is capable of producing secondary metabolites and other diffusible or volatile antifungal molecules capable of preventing sclerotia germination and controlling the mycelial growth of S. sclerotiorum , which may cause changes in the morphology of hyphae, such as oxidation, and still be able to control the development of the disease in situ, which will be tested in future works. It is concluded that cave bacteria have antifungal potential and that Bacillus sp. CMA 12 can be used to control the fungus S. sclerotiorum and to inhibit sclerotia germination as an important biotechnological product for the agricultural input industry.
Palavras-chave: antagonism, biological control, secondary metabolites | |||||