Essential Oils v.s E. Coli Bacteria

Here is another installment from Dr. Cole Woolley on the incredible power of essential oils, against the E. Coli bacteria:


Harmful strains of E. coli (Escherichia coli) bacteria are commonly in the news. Sometimes companies recall canned foods contaminated with E. coli bacteria. Other times you hear of people who got sick eating at the same restaurant – likely from E. coli bacteria.
The posted signs stating “Employees Must Wash Their Hands” cannot be missed in restaurants and food manufacturing facilities. Employees that do not properly wash and sanitize their hands after using the bathroom put the public at risk with E. coli bacteria. People who do not wash their hands or clothing properly can spread E. coli bacteria with a handshake. NOTE: tiny rod-like bacteria
TEA TREE Defense against E. coli Bacteria*************************
Tea tree essential oil provides some defense against E. coli bacteria that was swabbed across the entire petri dish medium. The sterile white pad in the center was soaked in tea tree oil, allowed to air-dry, then placed on the center of the petri dish swabbed with E. coli bacteria. The yellow-colored circle in the center of this petri dish shows the Inhibition Zone effect of tea tree essential oil.
The tea tree essential oil inhibited the growth of the swabbed E. coli bacteria throughout the Inhibition Zone. Tea tree oil will continue to inhibit E. coli bacterial growth until the essential oil molecules evaporate. The width of the Inhibition Zone is an indicator of the defensive strength of the essential oil against E. coli bacteria.  Note the ABSENCE of the Inhibition Zone in the E. coli dish that was not treated with essential oil.

Tea tree essential oil is predominantly composed of Oxygenated Monoterpenes, particularly the terpenin-4-ol molecule at about 40%. Tea tree also contains a wide array of bioactive Sesquiterpene molecules.

HELICHRYSUM and ORANGE Defense against E. coli Bacteria****
By contrast, helichrysum and orange essential oil do not provide any appreciable defense against E. coli bacteria. There is no apparent Inhibition Zone on the E. coli swabbed dishes.
 CINNAMON Defense against E. coli Bacteria***********************
Cinnamon bark oil produced a wide Inhibition Zone against E. coli bacteria. By comparison, cinnamon bark essential oil provided slightly greater inhibition against E. coli growth than tea tree essential oil.

The key defensive molecules in cinnamon bark oil are trans-cinnamaldehyde, eugenol, cinnamyl acetate, linalool, and benzyl benzoate. These naturally defensive molecules provide significant defensive strength against E. coli bacteria.

THYME Defense against E. coli Bacteria*************************
Thyme essential oil provides even greater defense against E. coli bacteria. Recall that thyme essential oil provided the 2nd widest Inhibition Zone against Staphylococcus aureus bacteria in last week’s post. Thyme’s defensive strength is centered on its composition of Oxygenated Monoterpenes thymol (about 10%) and Carvacrol (about 10%).

Temporary Defense – Essential Oil Evaporation****************
These studies only show the temporary defensive action of essential oils. They initially spread from the central white pad into the medium. This is what creates the Inhibition Zone. However, once the essential oil molecules begin to evaporate, the bacteria can reclaim territory within the Inhibition Zone. Some essential oils evaporate faster than others. This demonstrates the need to re-apply essential oils to surfaces in order to inhibit the growth of harmful bacteria.

Dr. Cole Woolley, the essential oil explorer

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