Effect of Δ-9-Tetrahydrocannabinol on the Growth of Common Gut Bacteria Δ-9-Tetrahydrocannabinol, or THC, is the most well-known compound in a group of organic lipids called Cannbinoids. Found in Cannabis plants, these substances have been used for thousands of years for many reasons. In recent years it is used for both recreational and medicinal purposes. The effects of Cannabinoids have been tested in many aspects of human health—all except for the human microbiome, which is the collection of microbes that inhabit our body. These microbes are important for the overall health of the body and substances that either assist or inhibit the microbe’s growth can lead to severe health problems. The purpose of this experiment is to test the effect THC may have on the growth of Escherichia coli and Enterococcus faecalis, two bacteria that commonly inhabit the human digestive tract. Authors: Kameron Gale, Dr. Chad Sethman E. coli and E. faecalis are two species of bacteria that are commonly found in the digestive tract of the human body. They are apart of the microbiome that helps the body with digestion, immune system health, gut regulation, and vitamin and hormone production. Marijuana, the plant in which THC is found, is becoming popular in medicine and legalization for medical use is happening nation-wide. Research areas using THC includes mostly the heart and brain, which is common for new medicines. This research focuses on testing THC against the microbiome, a system that is as important for human health has the other systems. To do this, growth curves were made and doubling time from these curves were obtained to compare bacteria exposed to THC and those which were not. Cultures of each species were prepared the day before each test. The Control Group: 2ml Triptocase Soy Broth 20µl of lab grade Ethanol The Experimental Group: 2ml Triptocase Soy Broth mg THC or 6mg THC 20µl of lab grade Ethanol Spectrophotometer was set to 620nm A tube was placed in and the Spectrophotometer was zeroed. Bacteria was added from the Overnight culture 25µl at a time Repeated until the absorbance read around 0.05 The tubes were placed in a waterbath incubator at 37ºC Absorbance was read every 30 minutes. Doubling Time: Growth curves were found for each tube The equation of the line, for each curve, was arranged to solve for (x) Y was set to 0.3 to find (x 1 ) Y was set to 0.6 to find (x 2 ) Doubling time = (x 2 - x 1 ) Figure 1 (Above): Growth curves of E. coli, showing change in absorbance over time for both the control and mg/ml THC. All data points are averages of three. Figure 3 (Left): Doubling time of E. coli, control vs mg/ml THC. Bars are averages of three. Figure 2 (Above): Growth curves of E. faecalis, showing change in absorbance over time for both the control and mg/ml THC. All data points are averages of three. Abstract: Introduction: Method: Results: Conclusion: The E. coli showed no statistical change in growth with or without the THC. However, in the case of E. faecalis, those bacteria that were exposed to THC showed little growth, to the point that no double time could be obtained. The only real difference between the two bacteria is their outer layers. In the case of E. coli, a gram negative bacteria, the membrane is composed of 3 parts; the inner cytoplasmic layer, a thin peptidoglycan layer, and an outer lipopolysaccharide layer. E. faecalis is gram positive and has a membrane composed of 2 parts; the inner cytoplasmic layer and a thick peptidoglycan layer. It could be that the THC is being trapped in the outer lipid membrane of the gram negative E. coli and not passing through, where the E. faecalis has no defense against THC passing freely through. Further analytical methods would be required to test this hypothesis and better understand the relationship going on between THC and these bacteria. Acknowledgements: I would like to thank the Waynesburg University Biology Department for funding and supplies for my research, Michael Cipoletti for help with information and the license for obtaining the THC used, and the Cred building for printing this poster.