ANTIMICROBIAL EFFECTS OF ZATARIA MULTIFLORA BOISS. ESSENTIAL OIL NANOEMULSION AGAINST ESCHERICHIA COLI O157:H7

Escherichia coli O:H7 is a zoonotic pathogen and has been found as an important
foodborne and waterborne microorganism. The objective of this study was to investigate the
antimicrobial properties of Zataria multiflora boiss. essential oils nanoemulsion on Escherichia Coli
O157:H7 in pasteurized milk and in vitro.
Materials & Methods: The essential oil’s nano-emulsion was prepared by inversion phase and its
particle size distribution was analyzed by dynamic light scattering method. Nano-emulsion’s
antimicrobial properties in BHI and pasteurized milk (1.5 and 3.2 % fat ) were investigated by different
methods such as agar diffusion, vapor phase diffusion, Minimum Inhibitory Concentration (MIC),
Minimum Bactericidal Concentration, (MBC) and microbial inactivation curve after 0, 15, 30, 45, and
60 min.
Results: The average droplet size was 66.5 nm. The diameter of inhibition zone in agar diffusion method
was 8.74±0.4 mm, and in the vapor phase diffusion zone was not formed measurable. And MIC and
MBC were 2500 μL/ml. Effects of three nanoemulsion dilution 0.1, 0.01, 0.001 on microbial inactivation
in BHI broth showed that in 0.1 and 0.01 dilution after 1 hour, 6 log reduction can be observed in
microbial population. In pasteurized milk with 1.5% fat, in the dilutions mentioned above, decreased by
approximately 3.5 log was observed in the growth of bacteria. In pasteurized milk containing 3.2% fat,
about 2.5 log reduction in microbial population for all three dilutions.
Conclusion: According to the results obtained in this study, we concluded that by optimizing this
method, this nanoemulsion can be used to adequately control microbial pathogens