In Vitro Antimicrobial Activity Of Secondary Metabolites Of Bacillus Cereus Against Rice Phytopathogens

Abstract

Rice is one of the most important foodstuffs in the family food basket. In recent years, rice production has decreased due to diseases that have caused great economic losses. In order to control the diseases, agrochemicals are necessary. As an alternative to replace agrochemicals, the application of beneficial microorganisms has been chosen, which provide protection against pathogens and promote plant growth. It is necessary to search for beneficial microorganisms capable of controlling phytopathogens that cause diseases in crops, in order to be able to substitute the application of agrochemicals, which cause environmental problems. To evaluate the in vitro antagonistic activity of Bacillus cereus against Burkholderia glumae and B. plantarii. Lot1-LIM, Lor2-LIM and Lor3-LIM morphotypes isolated from Lippia organoids, which were activated and purified on R2A medium, were used. Each morphotypes was inoculated on 3s medium for 7 days for the production of secondary metabolites. After this time, the bacterial extract was concentrated and evaluated on filter paper discs in King B culture medium previously plated with the pathogens. Morphotypes were molecularly identified from the 16S rRNA gene. Analysis of variance and Duncan rank multiple testing were applied for the inhibitory activity of the morphotypes against the pathogens. According to phylogenetic analyses, the morphotypes evaluated showed 100% homology with Bacillus cereus. Furthermore, they had the ability to control pathogen growth by releasing secondary metabolites such as sulcate, geraniol and geranate. These species are characterized by the production of secondary metabolites that control pathogen growth and in some cases promote plant growth through the release of siderophores and phosphate solubilization. The application of beneficial microorganisms with antagonistic potential may become a great alternative to substitute the application of agrochemicals in the future.