lab-4-selective-media-agar

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Studocu is not sponsored or endorsed by any college or university LAB 4 Selective Media & Agar Human Resources (Mohammad Ali Jinnah University) Studocu is not sponsored or endorsed by any college or university LAB 4 Selective Media & Agar Human Resources (Mohammad Ali Jinnah University) Downloaded by Brenda Ledbetter (bledbetter0627@gmail.com) lOMoARcPSD|28593260

Lab 4 Selective Media & Agar BIO250L ” Student Name: HANNAH Ejalonibu Access Code (located on the underside of the lid of your lab kit): AC-VGS01NE “ Pre-Lab Questons ” 1. What is the diference between chemically defned and chemically complex media? Give either a clinical or environmental research example for which each media type would be the most appropriate choice for culturing microorganisms. The difference between chemically defined media and chemically complex is Chemically defined media contains a known chemical on the other hand chemically complex media composition is unknown.For the growth of pathogenic bacteria chemically complex media can be used but Chemically defined media is used for in vitro culturing of animal and human cells. Chemically defined media would be the most appropriate choice for culturing micro organisms Examples include Nutrient Broth/Agar, Tryptic Soy Broth/Agar, and Blood agar. 2. Why is diferental media typically inoculated with isolated colonies that have been previously cultured on general growth media? In order for a more accurate examination of certain microbes, while eliminating others differential media is inoculated with isolated colonies that have previously been cultured on general media. 3. Use a textbook or a reputable internet source (such as www.cdc.gov) to research and describe a scenario in a lab or clinical setng in which a selectve and/or diferental test would be necessary. Downloaded by Brenda Ledbetter (bledbetter0627@gmail.com) lOMoARcPSD|28593260

Lab 4 Selective Media & Agar BIO250L ” Selective media allows organisms to grow and inhibit the growth of other organisms,and differential test is done to distinguish the microorganism. An example of this is adding a certain antibiotic to the medium to inhibit the growth of other organisms. “ EXPERIMENT 1: Bioprospectng for Starch Degrading Bacteria Data Tables Table 3: Starch Agar and Gram Iodine Results Sample Growth on Starch Agar? (Yes or No) Clear area around colonies? Do these bacteria contain amylase? A Yes no yes B Yes no yes C Yes yes yes D No yes no Post-Lab Questions 1. Why is cow manure used as a potental source of starch-degrading bacteria? (If you are not familiar with the process of digeston in cows, use a reputable internet source to inform your answer.) For potential source of starch-degrading cow manure is used as a bacteria because it contains the enzyme which is called amylase, which can break down complex carbohydrate molecules, such as starch. 2. What are some other potental sources of starch-degrading bacteria? In fermentation, soil, paper, food, and textile. Downloaded by Brenda Ledbetter (bledbetter0627@gmail.com) lOMoARcPSD|28593260

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Lab 4 Selective Media & Agar BIO250L ” 3. What component makes starch agar selectve for starch-degrading bacteria? Grams Iodine. 4. Why were each of the following steps performed in this experiment? a. Serial diluton: Serial dilution is used for the purpose of reduce the concentration of the microorganisms and obtain the number of cells on the media. b. Growth on the nutrient agar plates: For isolating and purification of the bacteria to be tested and identified. c. Streak on the starch agar plates: For isolating a sample and this technique helps to identify it on a new medium that’s why it is used. Insert a photo of your plates. Include your name and access code handwriten in the background of your photo. Downloaded by Brenda Ledbetter (bledbetter0627@gmail.com) lOMoARcPSD|28593260

Lab 4 Selective Media & Agar BIO250L ” “ EXPERIMENT 2: Selecton and Diferentaton of Body Inhabitng Gram-Positve Bacteria Data Tables Table 4: Experiment 2 MSA Growth Observations Surface Tested Growth (Yes or No) – Nutrient Agar Growth (Yes or No) – MSA Agar MSA color around colonies (Red or Yellow) Other Observations skin Yes Yes Yellow Covers all of medium nose Yes Yes Yellow Dots on MSA no dots on Nurtent countertop Yes Yes Yellow Growt hsimilar on both mediums control Yes No Yellow MSA: Colonies grew into control side Post-Lab Questions 1. What chemical in MSA confers selectvity? How? high sodium chloride because it makes it difficult to grow bacteria in it. Downloaded by Brenda Ledbetter (bledbetter0627@gmail.com) lOMoARcPSD|28593260

Lab 4 Selective Media & Agar BIO250L ” 2. What chemical makes MSA diferental? How? The chemical is mannitol because staphylococcus aureus can ferment it but not other staphylococcus species. 3. Why are the nutrient agar plates used in this experiment? In this experiment nutrient agar plates used. 4. Was there any growth on you MSA plates? Did any of the colonies change the color of the MSA? What does this tell you about the bacteria taken from each area of your body? Yes ,there are growth on my MSA plates and I saw the changes in colonies colour turn into yellow ,the bacteria is taken from my skin and nose. Insert a photo of your plates. Include your name and access code handwriten in the background of your photo. Downloaded by Brenda Ledbetter (bledbetter0627@gmail.com) lOMoARcPSD|28593260

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Lab 4 Selective Media & Agar BIO250L ” EXPERIMENT 3: Selecton and Diferentaton of Body Inhabitng Gram-Negatve Bacteria from Liquid Samples Data Tables Table 5: MacConkey Agar Results Sample Growth? (Yes or No) Colony Color (Clear or Red) Analysis Kitchen faucet No Red n/a lemonade Yes Red Small dots Ice tea Yes Red White colonies Experiment 3 Post-Lab Questions 1. What types of bacteria are inhibited on MacConkey agar? What ingredient(s) in MacConkey agar selects against those bacteria? Bile salt and crystal violet make MacConkey agar selective. Gram positive bacteria cells are inhibited on MacConket agar. 2. What ingredient(s) makes MacConkey agar diferental? lactose and ph indicator. 3. Using a textbook and a reputable online source (such as the CDC ), research and describe some potentally pathogenic members of the intestnal bacteria family Enterobacteriaceae . Which pathogenic species are lactose fermenters that will grow on MacConkey agar? Klebsiella ,Enterobacter,and Escherichia coli these are lactose fermenter. 4. Use a reputable internet source to research and describe some potentally pathogenic intestnal bacteria that do not ferment lactose that will grow on MacConkey agar. Pseudomonas ,Salmonella and Shigella do not ferment lacose. Downloaded by Brenda Ledbetter (bledbetter0627@gmail.com) lOMoARcPSD|28593260

Lab 4 Selective Media & Agar BIO250L ” 5. Use a reputable internet source to research and describe what variatons of MacConkey agar can be used to detect other species of bacteria. MacConkey agar can be used without Crystal Violet as a differential medium, but is less selective, and allows growth of staphylococcus. 6. How would you verify that the colonies that grew on a MacConkey agar plate were Gram- negatve? I would verify the colonies by there color. Lactose producing colonies would be red. Non-lactose colonies would have no color. 7. Look up the formula for MacConkey agar either in a microbiology textbook or online . Is this a chemically defned or a chemically complex media? Why is that important? MacConkey agar is considered a complex media. It is important because it provides the organic growth factors for bacteria. Insert a photo of your plates. Include your name and access code handwriten in the background of your photo. Downloaded by Brenda Ledbetter (bledbetter0627@gmail.com) lOMoARcPSD|28593260