Reference no: EM133394015

1. Identify the optimum temperature for prodigiosin production by Serratia marcescens. What color are the colonies? What color are the colonies at 37 degrees centigrade? 
2. Predict the optimum growth temperatures for E. coli and for B. stearothermophilus.                  

Pure Culture Techniques: 16 points

1. Describe two reasons for cooling the nutrient agar to 45^o C before inoculating and before pouring. 
2. Describe the negative impact of splashing media onto the sides of a Petri plate.
3. Discuss the reasons for flaming the loop before entering the culture and after the inoculation.
4. Name the two methods for obtaining a pure culture.  Describe one advantage to using the pour plate method and one advantage to using the streak plate method.
5. Describe the composition of a pure colony. 
6. When inoculating a Petri plate how should you handle the cover? 
7. Describe two advantages to using agar as a medium. 

Kirby-Bauer and Wet Mount of Eukaryotic Cells: 20 points

1. Define and distinguish between antibiotics and antimicrobials. 
2. What are the three possible outcomes for each antibiotic: microorganism pair in a Kirby-Bauer assay?
3. You perform a Kirby-Bauer test for a patient with a bladder infection caused by a Gram-positive organism. Considering the following data, which antibiotic would you prescribe? (Hint: do not forget to take into account that the bacteria in question is Gram positive)
   1. Chloramphenicol: 12 mm zone of inhibition
   2. Cefoxitin: 18 mm zone of inhibition
   3. Streptomycin: 14 mm zone of inhibition
   4. Ampicillin: 26 mm zone of inhibition                                                                                                                                                         
4. In the Kirby-Bauer method, define the term: zone of inhibition. How is it determined? 
5. Name three factors that influence the zone of inhibition.
6. Name the two different external structures of Gram positive and Gram negative organisms that make each more resistant to antibiotics. 
7. Name three components of a typical eukaryotic cell.
8. What is the general name of a membrane bound compartment within a eukaryotic cell?
9. Which part of the cell is stained by methylene blue?

Physiological Testing of Bacteria I: 25 points

1. What is respiration? How is it similar/different to fermentation? (4 points)
2. Describe the color changes of phenol red when it is exposed to an acid and a base. (2 points)
3. Describe how Durham Tube Sugar Fermentation test is used:
   1. What physiological characteristic is being tested?  (1 point)
   2. Name three possible end products produced during fermentation.  (3 points)
   3. What is the purpose of a Durham tube?  (1 point)
   4. What is the purpose of the pH indicator?       (2 points)
4. Why is it necessary to record the results of carbohydrate fermentation tests no later than 48 hours after inoculation? (2 points)
5. What is the purpose of the Methyl Red test? Describe the color changes in methyl red in the Methyl Red Test, when exposed to an acid or a base. (4 points)
6. What is the significance of a positive Nitrate Reduction Tests?
   1. What is the enzyme produced by the bacteria responsible for the test? (1 point)
   2. What are the two possible products formed during nitrate reduction? (2 points)
7.  Define the liquefaction that might occur after a gelatin stab. How does a positive test classify your unknown bacteria? (3 points)

Physiological Testing of Bacteria II & ELISA: 20 points

1. Describe the five steps in enzyme-linked immunosorbent assay (ELISA) antibody test. 
2. Describe how and why an enzyme is used in the ELISA test.
3. Identify three advantages in using the ELISA test. 
4. Describe the Starch hydrolysis test and describe the appearance and significance of a positive result.
5. Describe the Tryptophan hydrolysis test. 
   1. What is the reagent used? 
   2. What is the enzyme produced during a positive result?
6. Describe the appearance and significance of a positive urea hydrolysis test. 
   1. What is the product? 
   2. How does this change the pH of the media? 
7. Describe the Litmus Milk Reaction. 
   1. Name the pH indicator and other main component of the test solution. 
   2. Describe five possible reactions and the corresponding appearances in the test tube. 
8. Describe the metabolic activity that is tested in the Citrate Utilization Test.     
   1. What is the pH of the final product?
   2. Describe the appearance of a positive test result. 
9. Name the two tests for hydrogen sulfide production. 
   1. Which amino acid is degraded? 
   2. What is the product of the degradation? 
   3. Describe appearance of a positive test and how this end material is formed.