The objective of this study was to investigate the antimicrobial effects of carvacrol (CV) against Staphylococcus aureus (S. aureus) and Escherichia coli O157:H7 (E. coli O157:H7) strains in milk. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of CV against S. aureus and E. coli O157:H7 were determined. In addition, bactericidal kinetics and antimicrobial activity of CV against the aforementioned pathogens in milk over a period of 2 weeks were investigated. CV exhibited antibacterial activity against both foodborne pathogens tested. The MIC and MBC of CV against S. aureus were 15.0 and 20 mg/mL, respectively, whereas those against E. coli O157:H7 were 16.0 and 32 mg/mL, respectively. In time-kill assays, CV at MBC reduced the number of S. aureus and E. coli O157:H7 in milk to undetectable levels within 24 hr. The antibacterial effects of CV persisted for 14 days without any loss of activity. Results of this study suggest that CV has a potential antibacterial activity against foodborne pathogens such as S. aureus and E. coli O157:H7 in milk.

Introduction
 Materials and Methods
  Materials and milk samples
  Bacterial strains and cultures
  Determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)
  Time-kill Assay
  Persistence of antimicrobial activity of CV in milk
  Statistical Analysis
 Results
  MIC and MBC
  Time-kill assay
  Persistence of antimicrobial activity of CV in milk
 Discussion
 Acknowledgements
 References

• Youyoung Cho(Department of Nursing, Hanyeong College)
• Hu-Jang Lee(Research Institute of Live Sciences and College of Veterinary Medicine, Gyeongsang National University) Corresponding author