In Microbiology Lab 3 I chose the unknown culture #14 and ultimately identified it as Staphylococcus epidermidis bacteria. On a microscopic level I found the organism to be gram positive with a coccobacillus shape and both tetrad and cluster cell arrangement. I performed an isolation streak with S. epidermidis on Nutrient Agar which resulted in pinpoint, round, entire, and flat macroscopic morphology. I took a loopful of the organism from the Nutrient Agar and placed it on a slide to perform the catalase test. I added a few drops of 3% Hydrogen Peroxide and it resulted in bubble formation.
MacConkey agar was used to help determine this. The last test that helped determine this bacteria was the Methyl Red Voges-Proskauer broth. This test came back negative. In conclusion, I believe that the unknown bacteria number two to be Enterobacter aerogenes. In comparison of the descriptive chart and the comparative analysis sheet, 18 out 18 of the tests performed were alike.
The purpose of these tests were to determine how the bacterium reacted to glucose with and without oxygen. My findings reported a gram stain negative along with positive tests for glucose oxidation and fermentation. Next I performed an Indole Production Test. This test determines whether the microbe produces indole from the amino acid tryptophan. The results from this test were negative.
All results for this unknown can be found in the tables under results section of the report. The following tests were performed on unknown #15: * Gram stain | * Hydrolysis of starch | * Nitrate reduction | * Selective/differential media | * MR-VP | * Catalase/oxidase | * Enrichment media | * Citrate utilization | * DNase | * Isolation media | * Hydrolysis of Gelatin | * Esculin hydrolysis | * Gas-pak jar | * | * | * Candle Jar | * Indole production | * Triple sugar iron | * Thioglycollate tube | * Hydrogen sulfide production | * Litmus milk | * Fermentation of sugars | * Urea Hydrolysis | * Sulfur, Indole,motility | Unknown number 15 was assigned by the instructor. A differential staining
Jennifer Stewart March 8, 2013 Biology 105 Lab Report- Listerine Experiment Professor Jakubowski Examination of the Effectiveness of Listerine Mouthwash in Killing Bacteria Abstract Listerine Antiseptic Mouthwash claims to fight plaque, gingivitis, and bad breath germs, by rinsing the mouthwash in one’s mouth every twelve hours. A class of about twenty-five students conveyed an experiment to test if Listerine would, in fact, kill 99% of bacteria in one’s mouth over a period of 5 minutes. The results showed that the number of colonies on the plates decreased more than 50% after five minutes of waiting for the mouthwash to work. Introduction The number of bacteria on one human’s mouth is greater than the total number of people who lived on this earth. Many mouthwash companies all claim that their product will kill 99.9% of germs every use.
Calculate the Normality of the vinegar using the previously given equation. Na = (Nb)(Volumeb) (Volumea) C. Calculate the mass of the acetic acid in grams using the previously given equation. Massa = (Na)(GMWa) D. Calculate the percentage of acetic acid using the previously given equation. % Acid = Massa(g/L) x 100 1000g/L Discussion and Conclusion: Questions: LabPaq question guidelines: Answer questions A and G in the lab manual. Skip questions B, C, D, E and F in the lab manual, and answer these instead: A.
Eosin methylene blue and Mannitol agar plates will also be used to determine pH values. Test Three: Gram Stain – A basic technique which will help to distinguish between a Gram-positive and Gram-negative bacterium. Test Four: Catalase assay – Is to be used to determine whether the unknown bacteria will liberate free O₂ gas. Test Five: Oxidase assay – The cytochrome Oxidase will aid in determining whether the unknown bacteria has an absence of Oxidase or not. Test Six: Glucose assay – Whether an organism can respire or ferment glucose can be tested with this Glucose O/F medium assay.
Combining yeast, water, and 25% molasses in test tube B. Combining yeast, water, and 0% molasses in test tube C. One end of a tube was then placed in a cup of hot water and into test tube A. This step was repeated for test tube B, and C as well. As the test tubes heated up the BOB changed from blue to yellow indicating cellular respiration was occurring. Budding is a process in which a single cell produces offspring by pinching off part of the “parent” cell.
Methods which have been used throughout the semester to identify specific bacteria were applied to the unknown. The methods and procedures were followed as the laboratory manual for microbiology stated, unless stated otherwise. On day one, the first objective was to complete an isolation streak of the mixed culture onto nutrient agar. The goal of this test was to correctly isolate the two different bacteria. The nutrient agar was incubated at 37 degrees Celsius for 48 hours.
Duplicating a Color with Dye Trohimczyk, Brianna; Delgado, Theon Purpose: The purpose of this experiment is to match the color of the control dye with the new color of the dye produced in the test tube. Hypothesis: When two drops of red dye are placed with one drop of yellow dye in a test tube of water, the result will match the color of the controlled dye. Materials: * Four colors of food coloring (red, green, blue, yellow) * Test tubes * Pipets Procedure: 1. Place water into a plastic cup 2. Use the pipet to place 10ml of water into an empty test tube 3.