Evaluation of Antimicrobial Activity of Saccharomyces cerevisiae Against Enterotoxogenic and Enterohemorrahgic E. coli

Probiotics are useful microorganisms for health of communities. Saccharomyces cerevisiae is one of the effective microorganisms for treating of functional and gastrointestinal diseases in order to control pathogens. Enterohemorrahgic Escherichia coli (EHEC) and Enterotoxogenic (ETEC) are common pathogenic strains in all the world. The aim of this study was to evaluate the inhibitory effect of S. cerevisiae probiotic yeast on the growth of ETEC and EHEC. For preparation of the supernatant extract, the yeast suspension was centrifuged, and then, the supernatant was filtered. Extraction with ethyl acetate was performed in three hours. For preparation of lysate, the precipitate was washed and centrifuged. The supernatant was removed and sterilize distilled water was added. Cell lysis was performed by sonication and the liquid was centrifuged and filtered. Then, the MIC and MBC were determined by micro dilution method. The concentration range was 16-8192 μg/ml. The MIC and MBC of the supernatant against both ETEC and EHEC were 4096 μg/ml and 8192 μg/ml, respectively. Lysate in any of the concentrations showed no inhibitory effects on strains. The supernatant of S. cerevisiae has an inhibitory effect on growth of ETEC and EHEC. The lysate, probably due to the richness of the nutrients required for bacterial growth and not containing antibacterial compound, did not lead to such a repressive effect.