STUDY IN VITRO OF ANTAGONISTIC ACTIVITY OF BACILLUS ISOLATES AND SELECTION OF PROMISING PROBIOTIC STRAINS

The effectiveness of probiotic preparations is determined by the set of biological properties of the strains of cultures that are part of the probiotic, therefore, at the current stage of the development of biological antibacterial therapy, non-pathogenic probiotic spore-forming microorganisms, in particular bacteria of the genus Bacillus, are increasingly used to neutralize bacterial infections. The aim and tasks of the work were aimed at determining in vitro the level of antagonistic activity of isolates of Bacillus subtilis, Bacillus licheniformis and Bacillus coagulans isolated from poultry to standard test cultures of gram-negative and gram-positive microorganisms Pseudomonas aeruginosa АТСС 15442, Escherichia coli АТСС 25922, Salmonella typhimurium АТСС 29630 and Staphylococcus aureus ATSS 6538 and the selection of the most promising strains for the construction of the complex probiotic preparation "Biomagn". 27 isolates of the genus Bacillus were studied, isolated from poultry from poultry farms in Ukraine and identified to the species Bacillus subtilis — 13 strains, Bacillus licheniformis — 6 strains, Bacillus coagulans — 8 strains. Research on the determination of the level of antagonistic activity of research isolates of the genus Bacillus was carried out in vitro by two diffusion methods: the method of timed antagonism and the method of perpendicular strokes. Two promising strains of Bacillus subtilis (Bs–5 and Bs–9) were identified with very high and high levels of antagonistic activity against the indicator test cultures of microorganisms Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 15442, Salmonella typhimurium ATCC 29630 and Staphylococcus aureus ATCC 6538; two promising strains of Bacillus licheniformis (Bfl-1, Bfl-4) with a high antagonistic potential for action on indicator test cultures of microorganisms and one promising Bacillus coagulans (strain Bcg-5) with a medium level of antagonistic properties. The selected promising strains will be used for the construction of the complex probiotic preparation «Biomagn».