Скринінг штамів бактерій родів Bacillus і Pseudomonas, активних проти фітопатогенів роду Fusarium

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The using of biological preparations based on bacteria of the genera Bacillus and Pseudomonas is one of the most promising directions in the fight against pathogens of plant diseases. Quite a lot of preparations based on these microorganisms are known, but in some cases their application is characterized by insufficient activity against pathogens, as well as a reduction of the number of saprophytic soil microbiota, which negatively affects the phytosanitary state of the soil and reduces plants’ productivity. The aim of the work was to study the antagonistic activity of individual representatives of the genera Bacillus and Pseudomonas from different biotopes against phytopathogenic Fusarium isolates from affected winter wheat grown in the Odesa region. The largest number of Bacillus and Pseudomonas strains was isolated from the rhizosphere zone of plants. Screening of antagonistically active bacteria showed that this property was inherent in 92.4 % of Bacillus strains and 73.5 % – Pseudomonas strains. Bacillus spp. R14, R31 and S19 inhibited the growth of all selected fusaria (growth inhibition zones exceeded 20 mm). Pseudomonas spp. WR5 and WR7 also showed an antimycotic effect, but the sizes of the growth inhibition zones were less than 20 mm. Pre-cultivation of antagonistically active bacteria of the genera Bacillus and Pseudomonas on organic nutrient media contributed to a better manifestation of antimycotic activity of methanolic extracts of secondary metabolites of the studied strains. The determination of the minimum inhibitory concentrations (MIC) of the extracted metabolites against the selected Fusarium strains showed that the values ​​were variable, ranging from 1 mg/ml to 4 mg/ml depending on the specific strain-antagonist and the pathogen. To determine the spectrum and profile of secondary metabolites of antagonistically active Bacillus spp. R14, S19 and Pseudomonas sp. WR5 strains requires more extensive studies, including high-resolution mass spectrometry, as well as full sequencing and annotation of the genomes of these bacterial strains for their exact identification and detection of secondary metabolite clusters.