Statistical analysis. The statistical analysis was performed by using SPSS Version 21 (IBM Corp., NY). The mean inhibition zone for each group of nine observations was compared with the value of the disc diameter (6 mm) using the t-test. The GLM procedure was used to conduct a two-way analysis of variance (ANOVA) on the inhibition zones. The type of microorganism and amount of essential oil were used as factors in the full factorial model. Post-hoc tests for each amount of essential oil were conducted by using Tukey’s HSD method, in order to compare the effect on different types of microorganisms.