Lab 12 Assignment Phage titration problems
1) You are given a bacteriophage suspension with an undetermined number of bacteriophages per milliliter. You diluted this original bacteriophage suspension 1/1,000. Then, you mixed 0.1 milliliter of the diluted phage suspension with 0.1 milliliter of an E. coli suspension and soft agar medium (generating mixture “A”, with a total of 1 milliliter), and pour the entire volume of this mixture as an overlay onto a nutrient agar plate. After hardening, the plate was incubated for 24 hs. Enumeration of the plaques revealed 80 plaques on the plate after incubation. Based on this observation, what is the number of plaque forming units (pfu)/milliliter in the original bacteriophage suspension provided?
Final Answer Here: ____________ PFU/ml
2) You are given a bacteriophage suspension with an undetermined number of bacteriophages per milliliter. You diluted this original bacteriophage suspension 1/10,000. Then, you mixed 0.2 milliliter of the diluted phage suspension with 0.1 milliliter of an E. coli suspension and soft agar medium (generating “mixture A”, with a total of 1 milliliter), and pour the entire volume of this mixture as an overlay onto a nutrient agar plate. After hardening, the plate was incubated for 24 hs. Enumeration of the plaques revealed 110 plaques on the plate after incubation. Based on this observation, what is the number of plaque forming units (pfu)/milliliter in the original bacteriophage suspension provided?
Final Answer Here: ____________ PFU/ml
Water Quality Analysis
1. Where does New York city water come from?
2. What are indicator organisms?
3. What are coliforms? How do they differ from fecal streptococci?
4. What is the total coliform rule?
6. What is the membrane filtration method?
7. What is the multiple-tube fermentation method?
8. What is the IDEXX method?
9. Describe
each of the following media, what they are used for, and explain the way they work:
1. Lactose broth tubes with Durham tubes 2. EMB plates
3.
MacConkey agar plates 10. Make a chart
of expected results using the above media for the following two water samples:
A.
Water contaminated with E. coli
B.
Pure uncontaminated water
