Prunus mahaleb Inhibits The Gram-negative Bacterium Escherichia coli

Foodborne infections caused by gram-negative pathogens result in millions of illnesses worldwide. Transmission of foodborne infection by raw fruits and vegetables is increasing. A preventative treatment of produce that can kill gram-negative bacteria prior to consumption can reduce the risk of infection. Spices have been used as an effective preventative against foodborne infections in many cultures for centuries, thus these plants are possible sources of antimicrobials. In this study, Prunus mahaleb was screened for antimicrobial compounds because it has long been used as a spice in the Middle East. P. mahaleb seeds were ground in ethanol or isopropyl alcohol to a final concentration of 33-67 mg/mL. These extracts were tested for antimicrobial activity against Escherichia coli, Saccharomyces cervisiae, and Staphylococcus aureus in agar diffusion assays. The ethanolic extract (33 mg/mL) inhibited E. coli with a 3 mm zone of inhibition. The minimum bacteriostatic concentration is 62.5 mg/mL and the minimum bactericidal concentration is 50 mg/mL. The effect of the seed extract on bacterial growth rates is being determined. The effectiveness of the extract preventing E. coli survival and growth in fresh produce will be presented. These results suggest that P. mahaleb has the potential to prevent survival and growth of gram-negative bacteria in foods.