Answer these Microbiology questions. (answer each PART of question in 2-3 sentences, forming a paragraph for each question)
1. A microbiologist is attempting to culture bacteria from human feces and chooses to use LB agar, rationalizing that it is a rich medium. What does it mean to be a “rich” medium and what types of microbes does a rich medium select for? When he compares direct microscopic counts of microbial population density to the counts he obtains from cultivating of the colonies on the LB agar plate and incubating them at 25 degrees Celsius, he realizes that he has cultured only a small fraction of the colonic bacteria. Discuss three things wrong with his approach and how you would fix them to maximize recovery of the colonic microbiota.
2. The most common autotrophic organisms on Earth are photoautotrophs such as plants, eukaryotic algae, and cyanobacteria. It is possible for non-phototrophic microbes to be autotrophic. They use inorganic chemicals for energy and electrons. What descriptive name would these microbes have? Often these microbes are found deep in the ocean in geo-thermal vent regions. What temperature requirements would you suspect they have? Explain. Which celluler structure must be adapted to deal with this extreme environment? How might they be adapted? If these microbes lacked superoxide dismutase, catalase, and peroxidase what can you conclude about the effect of molecular oxygen on their growth? Explain. Since these microbes live in the ocean how would you categorize their salt requirements? Explain how they survive.
3. You have been hired to prepare microbiological media for a laboratory on campus. You stayed up watching the final episode of Breaking Bad and then blogged all night about it. When you finally get to work the next day you find that the autoclave is down for repair and you really need to make media for an experiment the lab director wants to conduct tomorrow. Can you boil the medium at 100 degrees Celsius for 15 minutes to sterilize it? Explain. What other common lab technique can you use to sterilize media without the use of an autoclave? Explain how this technique can work to help save your job! When you get home later that night, your mom tells you about the new antibacterial hand-soap she has purchased for the bathroom. You notice that it contains triclosan. Discuss two ways that triclosan can inhibit microbial growth. Why are scientists worried about the over-use of triclosan containing products?
4. Obviously, host cells do not “want” to be infected by viruses, yet they contain receptors that allow viral entry. Why do these receptors exist on the host cells and why can’t we develop antiviral drugs to block these receptors and eliminate viral attachment. The rabies virus is somewhat unusual in that it can infect a wide range of mammalian species. Given this information, what conclusions might you draw about the host cell receptor used by this virus? Explain. When someone is bitten by a rabid animal part of the treatment includes injection of antibodies that target the rabies virus. Explain how this treatment helps the person bitten by the rabid animal.
5) The students involved in the IIT Heritage Garden on campus are preparing to plan for the spring planting season. Some students are wondering how they can enrich the soil with regard to nitrogen supply. You suggest growing peas. They ask why? Explain how peas and their microbial symbionts will take care of the nitrogen issue for free. Some students want to use a rototiller on the soil. You worry that this could disturb the mycorrhizal fungi all ready growing in the soil. The students ask you to explain what you mean, how would you answer them? What type of symbiotic relationship do both of these symbionts have with their plant partner? Explain.
6) Mary is so worn down studying microbiology all of the time that she ended up with strep throat. The doctor prescribes some antibiotics to treat her infection. How will the antibiotics affect her normal flora? After the course of the antibiotics are complete her strep throat is gone, but now Mary is suffering from a yeast infection. What went wrong? A fellow microbiology student suggests that she start eating some yogurt. Why would they say that? Mary goes home for the weekend to visit her parents and her dad says that he was prescribed a proton pump inhibitor for his heartburn issues. Mary says he needs to take care to with food preparation and cooking as he could be at greater risk now for stomach and intestinal infections. He asks why? What will Mary tell her dad about his situation.