Antimicrobial Activity of Yerba Mate (Ilex paraguariensis) Aqueous Extracts against Escherichia coli O157:H7 and Staphylococcus aureus

Bioactive compounds from natural plant sources are becoming increasingly important to the food industry. Ilex paraguariensis is used in the preparation of a widely popular tea beverage (Yerba Mate) in the countries of Uruguay, Paraguay, Argentina, and Brazil. In this study, extracts of 4 brands of commercial tea, derived from the holly plant species, Ilex paraguariensis, were evaluated for their ability to inhibit or inactivate bacterial foodborne pathogens. The ultimate goal was to evaluate potential use of the extracts in commercial applications. Dialyzed aqueous extracts were screened for antimicrobial activity against Escherichia coli O157:H7 and Staphylococcus aureus. S. aureus was found to be the more sensitive to extracts than E. coli O157:H7. Minimum bactericidal concentrations (MBCs) were determined to be approximately 150 to 800 mu g/mL and 25 to 50 mu g/mL against E. coli O157:H7 and S. aureus, respectively. A Uruguayan brand had reduced activity against E. coli O157: H7 compared to the Argentinean brands tested. It was concluded that Yerba Mate could be used as a potential antimicrobial in foods and beverages against these pathogenic bacteria.