Lab 4 for Microbiology Lab from Straighterline

lOMoARcPSD| Lab 4 for Microbiology Lab from Straighterline Fundmtls Of Microbiology W Lab lOMoARcPSD| Lab 4 Selective Media & Agar BIO250L” Student Name: Access Code (located on the underside of the lid of your lab kit): “Pre-Lab Questions” 1. What is the difference between chemically defined 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 is a known chemical composition while chemically complex media contains an unknown chemical composition. 2. Why is differential media typically inoculated with isolated colonies that have been previously cultured on general growth media? Differential media is typically inoculated with isolated colonies that have been previously cultured on another media previously. 3. Use a textbook or a reputable internet source (such as ) to research and describe a scenario in a lab or clinical setting in which a selective and/or differential test would be necessary. Selective media allows organisms to grow and inhibit the growth of organisms. You can add a type of antibiotic to the medium that can inhibit the growth of organisms. “EXPERIMENT 1: Bioprospecting for Starch Degrading Bacteria Data Tables Table 3: Starch Agar and Gram Iodine Results Sample Growth on Starch Clear area around Do these bacteria Agar? (Yes or No) colonies? contain amylase? A Yes No Yes B Yes No Yes lOMoARcPSD| Lab 4 Selective Media & Agar BIO250L” Sample Growth on Starch Clear area around Do these bacteria Agar? (Yes or No) colonies? contain amylase? C Yes Yes Yes D Yes Yes Yes Post-Lab Questions 1. Why is cow manure used as a potential source of starch-degrading bacteria? (If you are not familiar with the process of digestion in cows, use a reputable internet source to inform your answer.) Cow manure is used as a potential source of starch-degrading bacteria because it contains an enzyme amylase which breaks down carbohydrate molecules. 2. What are some other potential sources of starch-degrading bacteria? Some sources include food, paper, soil, and fermentation. 3. What component makes starch agar selective for starch-degrading bacteria? Its ability to determine whether the organism can produce amylase or not. 4. Why were each of the following steps performed in this experiment? a. Serial dilution: Is used to reduce the concentration of microorganisms b. Growth on the nutrient agar plates: Isolates the bacteria to be able to be identified c. Streak on the starch agar plates: Isolates the sample and helps identify it on a new medium lOMoARcPSD| Lab 4 Selective Media & Agar BIO250L” Insert a photo of your plates. Include your name and access code handwritten in the background of your photo. “EXPERIMENT 2: Selection and Differentiation of Body Inhabiting Gram-Positive Bacteria Data Tables Table 4: Experiment 2 MSA Growth Observations Surface Growth (Yes Growth (Yes or MSA color around Other or No) – colonies (Red or Tested No) – MSA Agar Observations Nutrient Agar Yellow) Skin No No None N/A, observed for 5 days lOMoARcPSD| Lab 4 Selective Media & Agar BIO250L” Surface Growth (Yes Growth (Yes or MSA color around Other or No) – colonies (Red or Tested No) – MSA Agar Observations Nutrient Agar Yellow) Cloudy, had the most colonies on Nose Yes No None Nutrient Agar Observed for 5 days White, cloudy on Table Yes No None nutrient agar Observed for 5 days N/A Control No No None Observed for 5 days Post-Lab Questions 1. What chemical in MSA confers selectivity? How? It’s selective because sodium chloride has a high salt concentration and most bacteria cannot grow in those conditions. 2. What chemical makes MSA differential? How? Mannitol = used for fermentation 3. Why are the nutrient agar plates used in this experiment? Allow the growth of bacteria and are good for comparison 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. The skin and nose colonies turbid the pink/red MSA to yellow. This shows that the bacteria could have been staphylococci because it was able to ferment in the mannitol. lOMoARcPSD| Lab 4 Selective Media & Agar BIO250L” Insert a photo of your plates. Include your name and access code handwritten in the background of your photo. EXPERIMENT 3: Selection and Differentiation of Body Inhabiting Gram-Negative Bacteria from Liquid Samples Data Tables Table 5: MacConkey Agar Results Sample Growth? Colony Color Analysis (Yes or No) (Clear or Red) Sink Faucet Yes N/A Singular black dot Stream Yes Clear Clear/Darker speckled dots everywhere. Toilet Water No N/A None Downloaded by kevin wacira () lOMoARcPSD| Lab 4 Selective Media & Agar BIO250L” 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 salts and crystal violet are selective agents that inhibited growth of gram-positive bacteria on MacConkey agar. 2. What ingredient(s) makes MacConkey agar differential? Lactose and the color. 3. Using a textbook and a reputable online source (such as the CDC), research and describe some potentially pathogenic members of the intestinal bacteria family ENTEROBACTERIACEAE. Which pathogenic species are lactose fermenters that will grow on MacConkey agar? Enterobacteriaceae is classified as gram-negative bacteria and grown in higher pH. Some pathogens are escherichia coli, enterobacter, klebsiella, and proteus. 4. Use a reputable internet source to research and describe some potentially pathogenic intestinal bacteria that do not ferment lactose that will grow on MacConkey agar. Some pathogenic species that are lactose fermenters that will grow on MacConkey are salmonella, shigella, and proteus species. 5. Use a reputable internet source to research and describe what variations of MacConkey agar can be used to detect other species of bacteria. MacConkey agar can be used without crystal violet but is less selective. It can grow staphylococcus. lOMoARcPSD| Lab 4 Selective Media & Agar BIO250L” 6. How would you verify that the colonies that grew on a MacConkey agar plate were Gram-negative? Gram-negative colonies grow on MacConkey agar plates because they verify the growth. 7. Look up the formula for MacConkey agar either in a microbiology textbook or c. Is this a chemically defined or a chemically complex media? Why is that important? MacConkey agar is a chemically complex media and it’s important because it can provide nutrients to the microorganisms. Insert a photo of your plates. Include your name and access code handwritten in the background of your photo.