Avaliação do potencial de Bacillus megaterium e Bacillus velezensis no controle de fitopatógenos que acometem a cultura da soja

Abstract

Soybean is one of the main agricultural crops in Brazil and worldwide, but its productivity can be compromised by diseases caused by phytopathogenic fungi such as Fusarium crassistiptatum, Macrophomina phaseolina, Sclerotinia sclerotiorum, Colletotrichum truncatum and Phomopsis longicolla. One of the main strategies for controlling these diseases is the use of chemical fungicides; however, their effectiveness has been decreasing due to the development of pathogen resistance, in addition to negative environmental impacts. In this context, antagonistic microorganisms, especially bacteria of the genus Bacillus, have attracted increasing interest because of their potential as biocontrol agents and their contribution to more sustainable agricultural practices. The present study aimed to evaluate the biofungicidal potential of the strains Bacillus megaterium (BC003) and Bacillus velezensis (BC004) against soybean phytopathogenic fungi, with the goal of selecting promising isolates for the formulation of bioproducts. For this purpose, in vitro dual culture assays were performed, along with tests using volatile and non-volatile metabolites produced by the bacterial strains. The results indicated that Bacillus megaterium and Bacillus velezensis exhibit potential for the biocontrol of important soybean phytopathogens, including Sclerotinia sclerotiorum, Macrophomina phaseolina and Phomopsis longicolla. B. megaterium showed similar antagonistic activity in both liquid culture and pure strain assays. In contrast, B. velezensis exhibited greater antagonistic activity in liquid culture, with emphasis on the action of non-volatile metabolites against P. longicolla. These findings reinforce the relevance of Bacillus spp. as a valuable tool in the development of sustainable disease management strategies for soybean cultivation.