Antibacterial Inhibition of Common Cooking Spices Against Escherichia coli Mariah Weir Department of Biological Sciences, York College of Pennsylvania INTRODUCTION Escherichia coli is a natural part of the body’s intestinal flora which helps to maintain equilibrium. In normal indigenous locations of the intestine E. coli is harmless, but in the event that foreign bacterium from another source is introduced, it has the opportunity to multiply. The growth of the E. coli bacterium can cause anywhere from absolutely no symptoms to slight cases of gastroenteritis, urinary tract infections, to the extreme cases where death can occur. The majority of E. coli infections are due to the improper cooking of contaminated meat. According to the CDC, there are approximately 73,000 cases of illness per year caused by E. coli. Of these cases, 2,100 are hospitalized and 61 die due to complications from the infections caused. More recently, due to the education of the public on proper sanitation and higher regulations placed on restaurants and other food providing services, incidence rates of E. coli contamination infections have decreased 36%. 3 For thousands of years, cultures all across the world have utilized and developed cooking methods which contain spices, either native or foreign, for the more obvious reasons of improving taste, aesthetics, or for acting as a preservative. 2 Recent research has indicated that there are spices which have an inhibitory effect on the growth of several bacterial species. Links have also been made indicating that cultures located in hotter, southern climates use more spices and in greater quantities per recipe, many of which have greater inhibitory effects, than a culture in a colder, northern climate. 1 Some research has even been done on a few spices that indicate the presence of specific chemical components in the spice’s essential oils that are directly attributed to having inhibitory effects on bacterial growth. 4 The purpose of this experiment is to test and quantify the ability of ten common household spices to inhibit the growth of E. coli. METHODS RESULTS CONCLUSIONS  Through this experiment, the variation between spice’s antimicrobial inhibition is large and ranges between the complete inhibition of E. coli by cloves and the complete lack of inhibition by mint.  Many of these spices are used in meat-based recipes which would be consistent with the proposed role of inhibiting food-borne bacteria.  The spice’s antimicrobial inhibitory variation may be due, at least in part, to the active compounds in the spice’s essential oils. CURRENT AND FUTURE RESEARCH  Current ongoing research is being conducted to extract the essential oils from known microbial inhibiting spices. These essential oils are generally recognized as containing the active antimicrobial compounds. Instead of utilizing man- made chemicals as food preservatives, investigators have proposed using the isolated antimicrobial compounds as an alternative. 4  Another aspect of this field yet to be looked at could be to determine whether combinations of spices are more effective than one spice alone since most meat-recipes utilize multiple spices. LITERATURE REVIEWED 1 Billing, J., and Sherman, P.W Antimicrobial Functions of Spices: Why Some Like It Hot. The Quarterly Review of Biology. 73: Sherman, P.W., and Flaxman, S.M Protecting Ourselves from Food. American Scientist. 89: Enterotoxigenic Escherichia coli (ETEC). Available from : Accessed 2005 December Snyder, P Antimicrobial Effects of Spices and Herbs. Available from: Accessed 2006 January 23. ACKNOWLEDGEMENTS: Dr. Carolyn Mathur, Ph.D. Dr. Karl Kleiner, Ph.D. Prepare overnight nutrient broth culture of E. coli at 34.8°C Prepare 20 15mL conical tubes with 0.2g of each spice adding nutrient broth to a total volume of 10mL making a 2% suspension Add 100μL of E. coli Culture to 10 of the spice suspensions and 1 positive control tube 10 of the 2% spice conicals are controls with 1 negative broth control to ensure no contamination Keep in hot air agitator incubator overnight 1:10 dilutions of each conical and inoculate petri plates containing nutrient agar and incubate overnight OBJECTIVES of the STUDY  To test and d etermine whether ten common spices have antimicrobial inhibition against E. coli.  Spices used: Garlic, onion, allspice, oregano, thyme, cinnamon, cloves, cayenne pepper, mustard, and mint.  What can cause variation in antimicrobial inhibition? Perform a standard plate count Exponential growth of E. coli where doubling occurs in 33 minutes. Plated dilutions of mustard show decrease in number of colonies with every dilution.