Phytochemical characteristics and antimicrobial effect of Ziziphora clinopodioides and Coriandrum Sativum seed essential oils and their combination on some food borne pathogenic bacter

Essential oils and their components have known antibacterial effects. In this study the major components of essential oils of Coriandrum sativum seeds and aerial parts of Ziziphora clinopodioides were identified by means of GC-MS and the effect of different concentrations of them alone and in combination were then investigated in vitro to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against some foodborne pathogenic bacteria including Escherichia coli O157:H7, Staphylococcus aureus, Salmonella Typhimurium, Listeria monocytogenes and Bacillus cereus using broth micro-dilution method.  The most principle compounds composing Coriander seed essential oil (CEO) were Linalool L,γ-Terpinene, α-Pinene, Geraniol acetate and cymene. Thymol, α-Terpineol, Carvacrol, Linalool L and γ-Terpinene were the main chemical compounds found in Ziziphora essential oil (ZEO). Considering the results of MIC and MBC, B. cereus was the most sensitive (MIC 500ppm, MBC 1000ppm) and S. Typhimurium was the most resistant species (MIC 2000ppm and MBC 5000ppm) against CEO.ZEO also showed more antimicrobial effect against Gram positive bacteria Staphylococcus aureus, Listeria monocytogenes and Bacillus cereus (MIC 500ppm) compared to Gram negative bacteria of E. coli O157:H7andS. Typhimurium (MIC 1000ppm). The results of the evaluation of the combination effect of aforementioned EOs indicated that ZEO+CEO could synergistically suppress the growth ofS.aureus (MIC 125+250 ppm, 250+125 ppm). The results of this study showed that Ziziphora and Coriander EOs when used in combination are more effective against Gram+ bacterial growth especially against S. aureus which is an important bacterial