The Synergistic and Individual Anti-microbial Impacts of Green Tea and Ginger on Common Gastro-Intestinal Bacteria

Ginger and green tea, common substances found increasingly in the diets of the global population, have known anti-microbial effects and are commonly used together in teas. In the following experiment, the synergistic impact of green tea extract and ginger on two bacteria, Escherichia coli and Enterococcus faecalis, is investigated along with each supplements individual properties as an anti-microbial agent. In examining the effect that each test substance has on bacteria lawns in various combinations, we found no synergistic impact due to experiment design flaws. Both ginger and green tea had antimicrobial effects on E. faecalis but not on E. coli. The potential impacts of these findings are discussed. Introduction In 1928, Andrew Flemming discovered Penicillin. That moment marked a turning point in the world of western medicine. Antibacterial medication has become as commonplace as hand washing soap. Everything from acne to life-threatening infection is fought with antibiotics, often extremely successfully. Antibiotics and medicine reach beyond the laboratory. Many foods present antibiotic functions that often, unbeknownst to the eater, have reduced or limited the growth of bacteria in their body. Among those antibacterial foods that are becoming more common in our western diet are green tea and ginger. Both of these foods have been valued for anti-microbial properties for thousands of years in Asian cultures (Weil 1995). As this tradition moves west, research is being done to back the anecdotal evidence of healing stories. In research done on the effects of ginger on angiogenesis, a process that is closely connected to tumor growth and metastasis, gingerol (a main ingredient in ginger) is cited as having anti-bacterial tendencies (Kim et al., 2005). Similarly research on epigallocatechin-gallate, the main catechin in green tea extracts, was found to not only have anti-bacterial properties of its own but also to act in synergy to promote the antibacterial activity of tetracycline, a well known antibiotic (Roccaro et al., 2004). Given the current research and many years of successful medicinal use as an anti-microbial, this study set out to test whether green tea acts synergistically with ginger to limit the growth of two bacteria found in the human gastrointestinal system, Escherichia coli and Enterococcus faecalis. Escherichia coli is a gram-negative rod that includes a large number of strains ranging from common and benign to extremely pathogenic and linked to many diseases. The common enteric strain that was used for this experiment was chosen based on its important role in digestion of food for many mammals (Schaechter, 1992). Enterococcus faecalis, originally in the genus of Streptococcus, is a gram positive round (coccoid) bacteria that commonly occurs in the intestines of humans and other mammals. This bacteria is also know to behave pathogenically when in larger quantities, and are implicated in urinary tract infections and wound infections among other pathogenic activities (Holt, 1986). E. faecalis was chosen based on its common presence in the GI tract and its pathogenic nature when overgrown. The experiment tested both the anti-microbial effects of green tea and ginger separately and in proximity to each other on bacterial lawns of E. coli and E. faecalis over a 48-hour incubation. We hypothesized, if green tea and ginger act synergistically to limit the growth of both E. coli and E. faecalis separately, then we will see less bacterial growth, fewer rogue colonies, and greater zones of inhibition on plates that ginger and green tea appear together than those that have each test substance separately. The results of this testing shed light into the anti-microbial abilities of both test substances, potentially providing ground for natural alternatives to pharmaceutical antibiotic medication.