Original Research Paper by Kate Devitt (2019)
This research was included in the Virginia Junior Academy of Science Annual Research Symposium (2020)
Abstract
The purpose of this experiment is to evaluate the utility of oregano essential oil and tea tree essential oil as antimicrobial agents. Bacteria have acquired and grown antibacterial resistance mechanisms, a development that leaves many illnesses without viable treatments. Essential oils, a long-overlooked antimicrobial agent, represent a potential solution to this problem. For this experiment, oregano essential oil, tea tree essential oil, and distilled water (control) were tested in a Kirby-Bauer Assay (also called a disc-diffusion test) with Mueller-Hinton agar against non-pathogenic K12 Escherichia coli. Distilled water was chosen for the control because essential oils dilute the nutrient dense agar regardless of their properties. It was hypothesized that, if the effect of essential oils on K12 E. coli was observed, then oregano oil would result in the largest zone of inhibition. Twenty-five trials were conducted for each of the three levels of IV, and the bacteria were allowed to grow for 72 hours at 23 degrees Celsius, after which the diameter of the zone of inhibition was measured and all materials autoclaved. All data collected was statistically significant at a level of significance of 0.001 (df=48, critical t value= 3.503) and small SD ranges indicate high levels of precision within the experiment. The means support the research hypothesis that oregano oil would exhibit the strongest antimicrobial effects, however guidelines for interpreting the Kirby-Bauer Assay indicate the essential oils didn’t produce a large enough zone of inhibition to be considered an antimicrobial independently.
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