Essential Oils as Bacterial Disinfectants

Essential oils have become quite popular in natural medicine and their uses as an antibacterial household cleaner have been touted. We investigated how essential oils compared to bleach when used as disinfectants. Previously, we examined eight essential oils and two recipes (mixtures of oils) from Art Naturals for bacterial inhibition and found that six oils and both recipes consistently inhibited bacterial growth. In this study, we tested bacterial inhibition of individual oils, combinations/recipes of oils, exposure time to oils, concentrations of an oil, and build-up/toxicity of oil residues from doTERRA. Escherichia coli was plated onto McConkey agar as a lawn where treatment solutions were spotted onto each plate. Bleach and water served as positive and negative controls respectively. Thyme essential oil had the highest bacterial inhibition. Lemon essential oil did not inhibit bacterial growth. Inhibition zones were between 0-3cm out from the treatment location. To examine growth inhibition versus death, E. coli (MM294) was genetically transformed with pVIB containing lux genes to glow-in-the-dark during growth phase. Every essential oil that inhibited bacteria growth also showed a lack of glowing at the treatment location. Additionally, bleach and thyme oil were diluted (2%-0.2%) to determine the minimum inhibitory concentration (MIC). After 48 hours bleach’s MIC was 1% and thyme’s was 0.3%. These finding indicate that not only do essential oils kill E. coli, but some are as or more effective than bleach. Testing other species of bacteria, and essential oils’ potency on human skin cells are areas for future study