Student Name: Kit Code (located on the lid of your lab kit): Experiment 1- Effect of Chemical Germicides on Bacterial Growth Table 3: Experiment Results Sample Germicide Zone of Inhibition (mm) Relative Effectiveness Skin 10% Bleach 15-16 Yes 70% Isopropyl Alcohol 7-6 Minimal Hibiclens™ 11-15 Yes Control 0-2 No Nose 10% Bleach 10-11 Yes 70% Isopropyl Alcohol 6-7 Minimal Hibiclens™ 8-12 Yes Control 0-1 No Throat 10% Bleach 12-18 Yes 70% Isopropyl Alcohol 6-7 No Hibiclens™ 10-12 Yes Control 2-4 No Shoe 10% Bleach 12-14 Yes 70% Isopropyl Alcohol 6-7 No Hibiclens™ 10-12 Yes Control 3-2 No Post-LabQuestions 1. Which germicide wasthe most effective? Wasthe same germicide most effective for bacteria isolated from the different sources? What could explain this finding? 10% bleach was most effective. Yes, it was most effective for bacteria isolated from the different sources. Since bleach is a solution of sodium hypochlorite and water that is very effective in killing microorganisms, it is capable of entering microbial cells where it can react with many cellular components, disrupting and killing them. 2. Which germicide wasthe least effective? Wasthe same germicide least effective for bacteria isolated from different sources? What could explain this finding? 70% Isopropyl alcohol wasleast effective. Yes, it wasleast effective on the bacteria isolated frlm different places. This could be because, it erodes quicklg if left uncapped, evaporating most of its alcohol leaving behind only water which is not strong enough to destroy bacteria. Lab 7 Microbial Control BIO250L 3. Were any bacteria from a specific source most resistant to the different germicides? Ifso, which source? The germicidal resistance possessed of the gram-negative bacteria and gram-positive bacteria was the same, except for aeruginosa which was more resistant to most disinfectants in its naturally occuring state than most cells subcultured on labaratory media. Also pseudomonas aeruginosa too exhibited greater resistance to some disinfectants. 4. Did the dry filter paper serve as a positive or negative control? Negative control. 5. Look up the chemical formulas for bleach, isopropyl alcohol, and chlorhexidine gluconate (the active ingredient in Hibiclens). How does each chemical achieve its germicidal properties? Chlorhexiddine N,N'-bis(4-chlorophenyl)-3,12-diimino-2,4,11,13 tetraazatetrazecanediimidamide The attractions between negatively charged bacteria cells and chlorhexidine have resulted into Chlorhexidine's antimicrobial property. After chlorhexidine is absorbed into the organism's cell wall, it disrupts the intergrity of the bacterial cell membrane, resulting into a leakage of intracellular components of the bacteria. Isopropyl alcohol; Propan -2-ol(C3H80) Isopropyl alcohol is used in place of ethanol. It is also useful in disinfecting surfaces, and clinical thermometers. As for methyl alcohol, it is good at at disinfecting inoculation hoods. For example, removing and destroying fungal pores. Bleach-chlorine products(5-chloro-2-(2,4-dichlorophenoxy)phenol) Being oxidizing agents, they are capable of exhibiting etreme damage through oxidation of sulfydryl groups of enzymes. In order to form a hypochlorous acid (a microbidal), chlorine hasto interact with water. Insert photo of your cultures after incubation with your name clearly visible in the background