What’s On My Water?

1. What’s On My Water? Bacteria on Restaurant Lemon Wedges

2. Problem • Are restaurant lemon wedges free from bacteria? If not what is it that humans are ingesting?

3. Background Information • In 2008 Anne LaGrange Loving conducted an experiment with lemon wedges at restaurants to determine what exactly is on them • 53 out of 76 lemons that she swabbed were infested with bacteria • Lemon pulp is acidic; it registers with a pH of 4. This could possibly kill bacteria • Coliform bacteria is found in warm-blooded animals • Pathogenic bacteria tags along closely to coliform bacteria • Coliscan Easy Gel plates shows coliform bacteria as either blue or pink colonies

4. Hypothesis • If lemon wedges from restaurants are tested for bacteria and coliformsand are compared to clean lemons, the restaurant lemons will have bacteria present.

5. Materials • 15 lemon wedges: 10 from 2 restaurants ; 5 from a control lemon • 30 Coliscan Easy Gel plates • 30 cotton tipped sterile swabs • Bunsen burner • Gloves, lab coat, protective glasses

6. Procedure • Lemons were collected from 2 restaurants • Lemons were swabbed using aseptic technique • Swabs were inserted and swirled in the liquid form of Coliscan Easy Gel • Set dishes were placed in the incubator for 96 hours at 37⁰ Celsius • Colonies were counted by using a grid. 8 sample blocks were counted, and the sum was multiplied by 4 • All dishes were disposed by autoclave

7. Variables • Control: clean washed lemon • Independent: the restaurants • Dependant: the count of bacteria per wedge • Constants: temperature of incubator, amount of time in incubator, area of swabbing

11. T-test between Restaurants and Control Lemon

12. Conclusion • “If lemon wedges from restaurants are tested for bacteria and coliforms and are compared to clean lemons, the restaurant lemons will have bacteria present.”- was supported • No coliforms were found, so half of the hypothesis was rejected.

13. Sources of Error • The incubator may have been opened for long periods of time thus causing a temperature change • Some condensation was found on the plates • In only one plate, spores of mold were found; this plate was discounted

14. Further Research • A more comprehensive survey of restaurants • What exactly is on lemon wedges? • What type of soap kills the most bacteria?

15. Works Cited • Growth. (1999). Introduction to Bacteria [Fact Sheet]. Retrieved from University of Missouri- Saint Louis website: http://www.umsl.edu/‌~microbes/‌introductiontobacteria.pdf • Instructions. (n.d.). Retrieved November 12, 2010, from Micrology Laboratories website: http://micrologylabs.mennonite.net/‌Home/‌Our_Methods/‌Coliscan_Media/‌Coliscan_Easygel/‌Instructions • Loving, A. L., & Perz, J. (2007, December 1). Microbial flora on restaurant beverage lemon slices. Journal of Enviromental Health. Retrieved from http://www.thefreelibrary.com/‌Microbial+flora+on+restaurant+beverage+lemon+slices-a0172839589 • Morton, J. F. (n.d.). Lemon. Retrieved October 6, 2010, from Perdue University website: http://www.hort.purdue.edu/‌newcrop/‌morton/‌lemon.html • pH Panel. (n.d.). The pH Factor. Retrieved October 21, 2010, from Miami Science Museum database.

16. Works Cited Continued • Reynolds, G. (2007, March 21). Bacteria effective against fresh cut fruit contamination. Food Production Daily. Retrieved from http://www.foodproductiondaily.com/‌Quality-Safety/‌Bacteria-effective-against-fresh-cut-fruit-contamination • Stone, A. H. (1966). Chemistry of a Lemon. Englewood Cliffs, New Jersey: Prentice Hall. • Wassenaar, T., Dr. (2009, January 6). Food Safety [Virtual Museum]. Retrieved October 7, 2010, from http://bacteriamuseum.org/‌cms/‌Food-And-Water-Safety/‌food-safety.html