INVESTIGATING ANTIBIOTIC ACTIVITY OF THE GENUS BACILLUS STRAINS AND PROPERTIES OF THEIR BACTERIOCINS IN ORDER TO DEVELOP NEXT-GENERATION PHARMACEUTICALS

In recent years, we have witnessed a considerable growth in number of strains resistant to antibiotics. Therefore, research on new antimicrobial components that might be used for development of new-generation drugs is currently very important. We have studied antibiotic activity of Bacillus safensis, Bacillus endopheticus, Bacillus subtilis strains, isolated their bacteriocins, and evaluated their properties. The study was carried out in the scientific research institute for biotechnology, Kemerovo Institute of Food Science and Technology, in the city of Kemerovo. Strains of microorganisms were isolated from vegetables grown in Krasnodar region, namely, samples of Manas onions, Big Beef tomatoes, and Capia bell peppers. Antibiotic activity of the strains was evaluated in liquid nutrient medium. All test strains demonstrated some level of antimicrobial activity which varied from 18 to 91%. We established minimum inhibitory concentrations for the isolated strains based on measured optical density; MIC for Bacillus safensis was 1.5*106 CFU/сm3, for Bacillus endopheticus, 1.5*106 CFU/сm3, for Bacillus subtilis, 1.5*106 CFU/сm3. We then isolated respective bacteriocins and purified them by HPLC method. During disk diffusion tests, bacteriocin preparations proved active against Micrococcus luteus strain. Molecular weight was determined by PAGE electrophoresis. Molecular weight of bacteriocins varied from 3.6 through 4.21 kDа. Isolated bacteriocins were proved to belong to the lantibiotics class.