Antagonistic activity of Bacillus subtilis strains isolated from various sources

An important link in solving the problem of healthy food is the intensification of the livestock, poultry and fish farming, which is possible only in the adoption and rigorous implementation of the concept of rational feeding of animals. In the implementation of this concept required is the application of probiotic preparations. Currently, there is an increased interest in spore probiotics. In many ways, this can be explained by the fact that they use no vegetative forms of the bacilli and their spores. This property provides spore probiotics a number of advantages: they are not whimsical, easily could be selected, cultivated, and dried. Moreover, they are resistant to various factors and could remain viable during a long period. One of the most famous spore microorganisms, which are widely used in agriculture, is Bacillus subtilis. Among the requirements imposed to probiotic microorganisms is mandatory - antagonistic activity to pathogenic and conditional-pathogenic microflora. The article presents the results of the analysis of antagonistic activity of collection strains of B. subtilis, and strains isolated from commercial preparations. We studied the antagonistic activity on agar and liquid nutrient medias to trigger different antagonism mechanisms of B. subtilis. On agar media, we applied three diffusion methods: perpendicular bands, agar blocks, agar wells. We also applied the method of co-incubating the test culture (Escherichia coli) and the antagonist (or its supernatant) in the nutrient broth. Our results demonstrated that all our explored strains of B. subtilis have antimicrobial activity against a wild strain of E. coli, but to varying degrees. We identified strains of B. subtilis with the highest antagonistic effect that can be recommended for inclusion in microbial preparations for agriculture.