Anais do Congresso Paranaense de Microbiologia
IV Congress of Microbiology in Paraná

In recent years, agriculture had to adapt to increase agricultural production and meet the world society's food demand, and the intensive use of pesticides to control diseases in agriculture has promoted several environmental problems such as soil, water and food contamination. Among the alternatives to reduce the use of agrochemicals, biological control is standing out. One of the groups of microorganisms that are being studied due to its antibacterial potential is the Brevibacillus genus, which belongs to the group of actinobacteria. In general, microorganisms with antagonistic potential in the control of diseases and pests are capable of producing antibacterial compounds such as peptides and lipopeptides. Based on this, our research aimed to evaluate the antagonistic potential of LABIM17, as a microorganism capable of producing compounds that inhibit the microbial growth of bacterial phytopathogens and evaluate the minimum inhibitory concentration for them. For the development of the experiment, the antagonist strain, LABIM17, was identified via sequencing of the rDNA 16S gene. Secondary metabolites production started with activation steps in ISP2 medium and incubation at 28 °C for 24 h. The pre-inoculum was prepared with the colonies suspended in saline and the cell concentration adjusted to 108 CFU/mL, from which 30 µL was transferred to an Erlenmeyer flask containing 30 mL of Proposed Medium. For the production of antibacterial compounds, 400 ml of medium at 1% of the cell concentration was prepared. The medium was kept under agitation at 200 rpm for 168 hours at 35°C. To obtain the CFS, the production was centrifuged at 4°C for 15 min at 10.000 rpm and sterilized. Agar diffusion tests were carried out against the phytopathogenic bacteria Curtobacerium flacumfasciens, Xanthomonas vasicola, Xanthomonas citri and Pantoea ananatis, and the minimum inhibitory concentration (MIC) of the metabolites produced by the LABIM strain was evaluated. 16S analysis confirmed the strain as B. brevis. Microbial growth inhibited the growth of Pantoea ananatis by 42.6%, Xanthomonas citri by 40.8%, Xanthomonas vasicola by 39.8% and Curtobacterium flacumfasciens by 39.3%. The concentration of 125 µg / ml was enough to cause inhibition of C. flacumfasciens cells. The other bacteria were inhibited at a concentration of 500 µg / mL, except X. citri, which was inhibited by 1000 µg / mL. The results conclude that the B.brevis strain produce antimicrobial molecules effective against phytopatogens, being a good candidate for a microbiological control agent.