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Bacillus bacteria have attracted the attention of scientists as promising probiotics because of their versatile antimicrobial activity and established health benefits on the host. In this study, seven Bacillus strains were identified and analyzed for antagonistic activity against broad spectrum of food borne pathogens. All strains were identified as B. subtilis, based on the results of morphological, biochemical characterization and 16S rDNA sequence analysis. B. subtilis strains demonstrated antagonistic activity against test-cultures of pathogens, including multiresistant strains. Reference Bacillus strains, derived from the commercial probiotics did not show antagonistic activity against tested strains of pathogens. Three the most active cultures were studied for production of biosurfactants. Crude biosurfactants were isolated and analyzed by oil spread test and inhibition activity against Salmonella, Shigella and Staphylococcus cultures. Biosurfactants from three tested B. subtilis strains gave positive oil spread test. Inhibition activity of biosurfactants was found only against Staphylococcus strains. Production of biosurfactants depended on the incubation conditions of Bacillus culture. Best results were obtained after cultivation of bacilli in starch broth at 30°C. The concentration of produced biosurfactant increased in time with growth of bacteria and reached the maximum at 30 hours of incubation.
Timothy Moore (Tue,) studied this question.