BIO250L 4

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Grand Canyon University *

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250L

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Biology

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Jan 9, 2024

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Lab 4 Selective Media & Agar BIO250L ” Student Name: MA ERICKA RENEE SAUVE Access Code (located on the lid of your lab kit): UAWQHC Lab Report Format Expectations Utilize college level grammar and professional formatting when completing this worksheet. Submissions without proper formatting, all required photos or sufficient responses will be rejected. Pre-lab Questions 1. In this lab, you will conduct three different experiments that each cover the topic of selective media and agar. How are these experiments different from one another? Explain how the different media in each experiment are utilized in the context of selective vs differential media. These experiments will use different selective and differential media to target specific bacterial traits or growth conditions and pattern. Selective media will inhibit certain bacteria while allowing others one to grow, and differential media will distinguish between types of bacteria based on their metabolic reactions. Each experiment's media serves a unique purpose and objectives to identify certain bacteria, selecting for or differentiating between different bacterial types or characteristics.. 2. What is the difference between chemically defined and chemically complex media? Give an example (a clinical or environmental research application) of when you would use each type of medium to culture different microorganisms. The difference between chemically defined and chemically complex media is Chemical composition. Chemically defined media has known chemical composition while chemically complex has unknown composition . 3. Why do we grow microorganisms on general growth media first, before inoculating differential media? We grow on general growth media at first to make sure that they are viable and pure culture. This step provide baseline how the bacteria thrive under non-selective conditions before introducing them to the more specialized conditions of differential media. 4. What changes might you see on a differential plate that helps identify the bacteria? Colour changes , changs in morphology and zones will be formed indicating the activities of

Lab 4 Selective Media & Agar BIO250L ” enzymes. These changes will help to identify certain bacteria based on their metabolic reactions to specific substrates EXPERIMENT 1: BIOPROSPECTING FOR STARCH DEGRADING BACTERIA Introductory Questions 1. What are the objectives of Experiment 1? What media will you use? How does this media pertain to the topic of selectivity? The main objective is to isolate and identify ability of bacteria degrading starch. The media used likely contains starch as a substrate which identify amylase production, Which demonstrates selectivity by allowing only starch-degrading bacteria to grow. 2. What results do you expect to see in Experiment 1 if your selected colony is amylase-producing? If the colony is able to produce amylase, I would expect to see a clear zone around the bacteria on the starch agar plate after the application of iodine which indicates starch degradation. 3. What are some other potential sources of starch-degrading bacteria? Soil ,water bodies, human gut and decomposing meterial are the potential sources. 4. Why did you perform Step 10, under the Prepare Stock Solution section, in this experiment? This is important because Solution prepared is necessary for later steps of experiment. 5. What kind of media did you use initially, and why? The initial media used isnon-selective, nutrient-rich medium to make sure the growth of a wide spectrum of bacteria before selecting for specific traits. 6. What is the purpose of the final section of this experiment? It confirms the presence of amylase-producing and startch degrading bacteria, and possibly preparing for further characterization or application of the findings..

Lab 4 Selective Media & Agar BIO250L ” Data and Observations In the table below, report your observed growth corresponding to each plate. Denote whether there was growth on the starch plate, whether or not clear areas formed around the colonies that grew. Table 1: Starch Agar and Gram Iodine Results Provide a clear, high resolution photo of your plates after incubation with the lids removed. For credit on this lab, your photo must show the growth that is reported in your tabulated data, must depict the correct media with the iodine added and must also include your handwritten name in the background. Sample Growth on Starch Agar? (Yes/N) Clear area around colonies? (Y/N) A Yes N B Yes N C Yes Y D Yes Y

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Lab 4 Selective Media & Agar BIO250L ”

Lab 4 Selective Media & Agar BIO250L ” Results and Discussion 1. Describe the results of your starch test. Colonies grow on all samples with clear around zones are formed on sample C and D which means starch degrading bacteria are in sample C and D. 2. Do the plates contain starch degrading bacteria? How do you know? Yes sample C and D plates contain startch degrading enzyme because of clear zone formed around each colomies mentioning the presence of amylase EXPERIMENT 2: SELECTION AND DIFFERENTIATION OF GRAM POSITIVE BACTERIA Introductory Questions 1. What are the objectives of Experiment 2? What media will you use? How does this media pertain to the topic of selectivity? The main objectiveare is to isolate and differentiate between cerain Gram-positive bacteria. This involves identification and characterization of specific strains based on their growth conditions,patterns, morphology, and biochemical reactions. Mannitol Salt Agar or Columbia CNA agar will be used because they allow the grwoth of gram positive bacteria and inhibit the Gram-ve bacteria 2. What results do you expect to see from Experiment 2 if the microbes are non-fermenters? What if they are fermenters? If the microbes are non- fermintings, they will typically don't change the color of the medium. On a Mannitol Salt Agar, non-fermenters will not produce any changes the yellow color which ks associated with mannitol fermentation. If they are fermenters, they will metabolize the specific substrate in the given medium, often changing the color of the agar. For instance, fermenters on Mannitol Salt Agar will turn the medium cloudy . 3. What chemical in MSA confers selectivity? How? High concentration of sodium chloride in MSA make it Selective because most bacteria can't grow on this .

Lab 4 Selective Media & Agar BIO250L ” 4. What component(s) makes MSA differential? How? Mannitol which is used in fermentation. 5. Why are the nutrient agar plates used in this experiment? Because they allow the growth of bacteria which is good for comparison.

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Lab 4 Selective Media & Agar BIO250L ” Data and Observations In the table below, report the growth that was observed on each of the plates and their corresponding source. Denote whether there was growth on the nutrient plate and MSA plates, and then denote the color of the MSA around the colonies. Also denote any other pertinent observations. Table 2: MSA Growth Observations Surface Tested Growth (Y/N) – Nutrient Agar Growth (Y/N) – MSA Agar MSA color around colonies (Red/Yellow) Other Observations Nose Yes No None Cloudy Observed for 5 days on nutrient agar Table Yes No None White and cloudy Observed for 5 days on nutrient agar plate Skin No No None N/A Observed for five days Controle No No None N/A Observed for five days Provide a clear, high resolution photo of your plates after incubation with the lids removed. For credit on this lab, your photo must show the growth and color that is reported in your tabulated data and must also include your handwritten name in the background.

Lab 4 Selective Media & Agar BIO250L ” Results and Discussion 1. Review the photo of your agar plates. Describe the color around the colonies. Did any of the colonies change the color of the MSA? Yes colonies from nose and table chages the colour to cloudy. 2. What does the color of the agar tell you about the bacteria taken from each area of your body? Colour of agar indicates the growth of specific bacteria on plates. EXPERIMENT 3: SELECTION AND DIFFERENTIATION OF GRAM-NEGATIVE BACTERIA Introductory Questions 1. What are the objectives of Experiment 3? What media will you use? How does this media pertain to the topic of selectivity? The main objective of this experiment is to identify and differentiate between gram negative bacteria media used in this experiment is Mconkey Ager and EMB agar plates because it allows gram negative bacteria to grow and gram positive bacteria to inhibit 2. What results do you expect from Experiment 3 if your growth ferments lactose? I expect a color change if growing colony fermennts lactose On MacConkey Agar, lactose fermenters change the medium pink or red due to acid production, while non-fermenters remain colourless. 3. What types of bacteria are inhibited on MacConkey agar? What ingredient(s) in MacConkey agar selects against those bacteria? Gram positive bacteria are inhibited by using MacConkey agar it uses bile salts and crystal violet as selective agents. 4. What ingredient(s) makes MacConkey agar differential? Lactose.

Lab 4 Selective Media & Agar BIO250L ” 5. Look up the formula for MacConkey agar either in a microbiology textbook or online . Is this a chemically defined or a chemically complex media? Why is that important? This is not chemically defined but chemically complex Media it is important because it offers a rich environment for a wide spectrum of bacteria to grow, which is crucial when we are trying to isolate and differentiate between specific types of bacteria that might have complex nutritional needs. Data and Observations In the table below, report the growth that was observed on each of the plates. Also denote Table 3: MacConkey Agar Results Provide a clear, high resolution photo of your plates after incubation with the lids removed. For credit on this lab, your photo must show the growth and color that is reported in your tabulated data and must also include your handwritten name in the background. Sample Growth? (Yes or No) Colony Color (Clear or Red) Skin faucet Yes N/A Stream Yes Clear Toilet water No N/A

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Lab 4 Selective Media & Agar BIO250L ” Results and Discussion 1. Describe the growth you observed on the MacConkey Agar. There was growth on skin faucet and skin when exposed to MacConkey agar. The colour of colony was clear are stream sample . 2. For each plate, provide an analysis of the results. What does the color of the colonies for each of the samples mean regarding the interpretation of the results? In all cases, the Absence of color change (pink or red) determines that whether Gram-negative bacteria are present, they do not ferment lactose. This information is very useful for understanding the types of bacteria in each environment and can guide further testing or treatment if necessary.Color of each colny determines presence and absence of certain strains of bacteria

BIO250L 4

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