Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus cereus can cause food poisoning and digestive disorders in human beings. Propolis has been known as an antimicrobial agent against bacteria. Studies shows the in-vitro antimicrobial activity of propolis extract on bacterial strains.study, we evaluated antibacterial effects of propolis alcoholic extract on Staphylococcus aureus (ptcc1112), Bacillus cereus (ptcc1247) and Pseudomonas aeruginosa (ptcc1707) for three times. The results showed that the antibacterial activity and inhibition diameters for Staphylococcus aureus, Bacillus cereus and Pseudomonas aeruginosa (in a propolis extract concentration of 5.25 mg / ml) were respectively 18.66±0.58, 18, 14.33±0.58, respectively. S. Aureus had the highest sensitivity and Pseudomonas aeruginosa showed the highest resistance to alcoholic extract of propolis. The minimum inhibitory concentrations (MIC) for Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus cereus were 0.656, 0.656 and 2.62 mg/ ml respectively and the lethal concentrations (MBC) for Clostridium sporogenes, Escherichia coli and Staphylococcus aureus, were 0.656, 0.656 and 2.62 mg/ ml respectively.
Conclusion: The alcoholic extract of propolis had inhibitory and antibacterial effects on Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus cereus. Considering organoleptic effects of propolis extract, it can be used as a preservative in food.