Title of Project Name & Name 2 011-2012

1. Title of ProjectName & Name2011-2012 Introduction Abstract Discussion • Hand sanitizer brands advertise for killing 99.99% of germs and are used to prevent the spread of bacteria. The active ingredient is ethyl alcohol. • There is contradicting information about whether more than 60% or 50% concentration of ethanol is most effective (Franklin 2006) (Fendler, Groziak 2002). • This lab determined the efficacy of varied ethanol percentages (0% -80%) in killing E.Coli, using chicken broth as a nutrient broth. • Samples of each solution were placed in agar, a gelatinous substance, to plate and count bacteria. • Ineffectiveness or effectiveness of the different solutions of ethanol and chicken broth to kill bacteria can be compared to different percentages of ethanol in hand sanitizers. EFFICACY OF ETHANOL AGAINST E. COLI. Saif Ahmed and Emily Nordquist. The purpose of this lab was to test how effective ethanol is against bacteria, specifically Escherichia Coli. To test how effective ethanol is against E. Coli, solutions of chicken broth were mixed in different percentages of dilution. There were ten 200 mL beakers of solution total; two were 100% chicken broth, two were 80% chicken broth and 20% ethanol, two were 60% chicken broth and 40% ethanol, two were 40% chicken broth and 60% ethanol, and the final two were 20% chicken broth and 80% ethanol. After all of the solutions were made and after bacteria colonies were made in ten different agar plates, the two were mixed. To mix them, 1 mL of each solution was put into their respective agar plates. After a night of settling, results showed that there was no bacteria in any of the agar plates except for the two that did not have any ethanol. However, the lab did produce some unexpected results: at the bottom of almost every single solution mixture was an unknown white substance. However, in beakers 3 and 4 which had ethanol levels of 20%, the white substance was not present. Keywords: Ethanol, chicken broth, E. Coli, agar plate, Petri dish, • The lab yielded unexpected results and refuted the hypothesis that the E.Coli would survive under a 60% concentration of ethanol. • This proves that the chicken broth did work as a sufficient nutrient broth for E.Coli. However, this also shows that E.Coli did not survive in 20% or higher concentrations of ethanol. • Figure 5 :Petri Dish #2 Figure 6: Petri Dish #3 • These results do not conclude that 20% ethanol concentrations kills all bacteria; there was an unexpected reaction between the chicken broth and ethanol forming an unknown white substance. • This white substance appeared in all beakers except for beakers 3 & 4 (20% ethanol concentrations) and appeared more solid in beakers 5-10 while seeming more liquidy in beakers 1 & 2. • There is most likely no substance in beakers 3 and 4 because the ethanol and chicken broth had fully reacted with each other at a 4-1 ratio (80% chicken broth, 20% ethanol) and no layers were able to form. • It also shows that a more accurate test to determine at what concentration of ethanol E.Coli will be killed would be to test ethanol percentages between 0% and 20% • A potential error that could have affected the lab results was that there was an unequal distribution of E. Coli because it was mixed in a liquid solution, which does not guarantee equal distribution. • This lab only guarantees that ethanol will eliminate E. Coli at concentration levels of 20% or above, not all bacterial substances • This lab also only guarantees the elimination of E. Coli in chicken broth, not necessarily on bodily surfaces. • If E.Coli is grown in circumstances similar to the chicken broth nutrient solution, it will be killed with 20% ethanol hand sanitizers. • Figure 7: barely noticeable white Figure 8: clearly visible solid white substance in a more liquidy form substance at the bottom. Results Methods • Ten solutions with varying alcohol concentrations were made by mixing the ethanol with the chicken broth. Bacteria broth was made with water to stimulate the growth of E.Coli. • Bacteria were collected from the provided test tube of E.Coli and put into the bacteria broth. Then bacteria was moved into each ethanol and chicken broth solution. • Agar was created in Petri-dishes. By plating, the Petri-dishes were then exposed to the different chicken broth and ethanol solutions. • Counting showed colonies subject to the dehydrogenation of ethanol. • The data was then compared to three different types of hand sanitizer containing ethanol concentrations of 62%, 65%, and 70%. Analysis • No bacteria colonies present in Petri-dishes 3-10 • Several colonies of bacteria in Petri-dishes 1 & 2 as the agar appeared much cloudier than before and showed around twenty small white circles (bacteria colonies). • White substance appeared in beakers 1 & 2 and 5-10. • Beakers 1 & 2 had a more liquid like white substance (Figure 3) whereas beakers 5-10 had a more solid substance that looked fuzzy in texture • No white substance visible in beakers 3 & 4. Remained clearer. Figure 1: Ethanol-Chicken Broth Solutions Figure 3: White Substance Solution 1 References Comparison study on disinfectant efficiency of ethanol, bleach and anti-bacterial hand soap against e.coli and mixed cultur. (n.d.). Retrieved from http://www.cte.ku.edu/gallery/visibleknowledge/sturm/files/StudentWork Documents/final Lab Project/group_b_report.pdf Fendler, E., and P. Groziak (2002, February). Efficacy of alcohol‐based hand sanitizers against fungi and viruses. Retrieved fromhttp://www.jstor.org/stable/pdfplus/10.1086/503455.pdf?acceptTC=true Franklin, Deborah (2006, March 21). New York Times: Hand Sanitizers Good or Bad. Retrieved from http://www.nytimes.com/2006/03/21/health/21cons.html Fletcher, M. (1982, August 02). the effects of methanol, ethanol, propanol and butanol on bacterial attachment to surfaces. Retrieved from http://mic.sgmjournals.org/content/129/3/633.full.pdf Sherwood, Chris (2012, February 28). How Does Hand Sanitizer Kill Bacteria. Retrieved from http://www.livestrong.com/article/88193-hand-sanitizer-kill-bacteria/ Figure 2: Agar in Petri-dishes Figure 4: Petri dish #1