Lab 6 - Micro PDF

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Lab 6...

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“Lab 6 Microbial Ecology”

“BIO250L”

Student Name: Tonya Coty Access Code (located on the lid of your lab kit): AC – 39HTD1K “Experiment 1- Mold Growth on Bread and Fruit- What are Optimal Conditions for Fungal Growth?” “Table 1: Growth Results” “Condition ” “BrightControl” “BrightWater” “BrightSugar” “BrightLemon” “BrightVinegar” “DarkControl” “DarkWater” “DarkSugar” “DarkLemon” “DarkVinegar” “Table Key:”

“Extent of Growth” “Day 6” “Day 8” “Day 10” 0 0 1

“Day 2” 0

“Day 4” 0

“Day 12” 1

“Day 14” 1

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“0 = no growth” “1 = little/some growth (1-25%)” “2 = moderate growth (26-50%)” “3 = heavy growth (51-75%)” “4 = extensive growth (76-100%)”

“Post-Lab Questions” “1. Which condition produced the most mold growth? The fastest? The least? The slowest?” The bright sugar condition seemed to produce the most mold growth and it was also the fastest. The bright venigar had the least amount of mold growth and was also the slowest. “2. Based on your results, what conditions are most favorable for mold growth on bread and apples?” A dark warm location will provide the most favorable space for mold growth with sugar water added to it making it moist.

“Lab 6 Microbial Ecology”

“BIO250L”

“3. Would these conditions apply to all fungal growth? Why or why not?” The dark moist conditions would apply to all fungal growth but at different rates of speed because many molds grow in dark moist areas. Mold grows well indefinitely in the dark when other environmental conditions favor its development. In warm areas, mold grows faster in the dark, where increased moisture means a higher relative humidity. “4. How would changing the type of bread (fresh from a bakery, no preservatives vs. prepackaged with preservatives) affect the results? Describe an experiment that would test your hypothesis.” Packaged breads contain preservitives to help maintain freshness and delaying mold growth so a fresh loaf without preservitives will go bad faster. To test this theory I would need a piece of fresh bread and packaged bread placed in the same conditions, same type of bag, 1 of each in warm dark conditions and 1 of each in warm bright conditions. “5. How would changing the incubation temperature of the bags affect the results? Describe an experiment that would test your hypothesis.” For mold to grow it must have warm and moist conditions to thrive, the cooler it is it will get less moisture delaying the growth. To test this theory I would need 3 pieces of bread each in there own plastic bag. I would place each one in different tempurtures, 1 at room temperature, 1 in the fridge, and 1 in the freezer and then check daily for growth in each location. “6. Look up the pH of lemon juice and vinegar. Based on your results and your knowledge of favorable environmental conditions for fungal growth, what can you conclude about the effect of pH on growth? How would making the pH more basic affect growth?” Vinegar has a pH between 2 – 3 and leman has the pH of about 2. Lemon juice and vinegar reduce the number of pathogens so it is going to slow done the growth. Making the pH more basic will speed up the growth because it is less acidic making it a more favorable location for the fungus to thrive. “7. What is the source of the mold that grew on the samples?” The source of the mold had most likely come from the bread. Because of the ingredients in bread, it is an good source of nutrition for molds to thrive and grow. The bread also contains a limited moisture content, which is why mold can grow so well instead of bacteria or yeast that requires higher moisture levels to survive. “Insert photo of your cultures after incubation with your name clearly visible in the background:”

“Lab 6 Microbial Ecology”

“BIO250L”

“Experiment 2- Fluid Thioglycollate Medium to Assess the Effect of Oxygen on Bacterial Growth” “Table 2: Experiment 2 Results” “Sample Location” “Control” “Skin” “Nose” “Throat” “Shoe”

“Growth Location in FTM”

“Oxygen Category”

None Minimal A ¼’ from the bottom of the tube Minimal Thru out the tube

Facultative Facultative Aerotolerant or anerobic Facultative Aerotolerant or anerobic

“Post-Lab Questions” “1. What does the pink band in the FTM indicate?” The pink band in the FTM indicates the presence of oxygen. “2. What would be the effect of using FTM tubes with broad pink zones?” The effect of using FTM tubes with broad pink zones would be to understand what kind of bacteria grows best with and without oxygen.

“Lab 6 Microbial Ecology”

“BIO250L”

“3. Provide an explanation as to why bacteria from each location displayed its pattern of growth?” The bacteria from each location displayed its pattern of growth by the sodium thioglycolate that consumes oxygen and permits growth of obligate anaerobes. “4. Why is it important to pull the inoculating needle out of the FTM via the same path you inserted it?” It is important to pull the inoculating needle out of the FTM via the same path you inserted it to avoid allowing more oxygen or removing oxygen from the tubes that could effect the results of the test. “5. How would you explain the presence of bacterial growth in the control FTM tube?” The presence of bacterial growth in the control FTM tube could be explained by either the contamination of the agar plate or the inserting needle. “Insert photo of your cultures after incubation with your name clearly visible in the background:”...