Antimicrobial and antibiofilm effects of Satureja hortensis essential oil against Escherichia coli and Salmonella isolated from poultry

Background and Objectives: Escherichia coli and some Salmonella serovars cause various disease manifestations in poultry leading to significant economic losses. The widespread and imprudent use of antibacterial agents in poultry flocks have increased resistant to many antibacterial agents which has become a major public health concern. Some medicinal plants may be alternative to antibacterial agents. The purpose of this study was to investigate the antibacterial and anti-biofilm activity of summer savory essential oil against E. coli and Salmonella isolated from poultry. Materials and Methods: The essential oil was extracted using a Clevenger apparatus and subsequently its compounds were determined using GC-MS. Antibacterial properties of essential oil were determined by disc diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). To evaluate the anti-biofilm properties the Microtiter plate test was used. Herbal essential oil was extracted and its compounds were identified correctly. Results: The major components of Satureja hortensis essential oil were thymol (41.28%), γ-terpinene (37.63%), p-cymene (12.2%) and α-terpinene (3.52%). The inhibition zone diameter in the disc diffusion test for E. coli and Salmonella were 32 ± 3 and 38 ± 4 mm, respectively, which was confirmed by MIC and MBC values. Regarding anti-biofilm activity, the MIC/2 concentration of S. hortensis significantly inhibited biofilm formation of E. coli. However, inhibition of biofilm formation of Salmonella was shown at concentration of MIC/2 and MIC/4. Conclusion: Based on our results, S. hortensis essential oil showed the growth inhibition and bactericidal activity against E. coli and Salmonella. Moreover, this study demonstrated anti-biofilm activity of S. hortensis essential against both tested bacteria.