who can help me answer this questions on phage titer I mist this lab last week a
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who can help me answer this questions on phage titer I mist this lab last week and lost now.
Week 8 - Phage Titer Post-Lab Questions 1. Why did we not use turbidimetry as a part of our phage titer procedure, the way we did with the bacterial population counts? HINT: think about how the phage solution you were given looked (1 pt) the phage solution was rather clear and it would be inconclusive with the turbidimetry test. 2. Phage Titer Problems (1 pt each) (a) You observe 78 plaques on an agar plate which received a phage dilution of 104. What is the PFU/ml in the original phage sample? (b) An agar plate which receive a phage dilution of 10 produced 298 plaques after incubation, while the 102 plate produced 31 plaques. Since both plates are countable, use data from both toe determine the PFU/ml in the original phage sample. (c) A phage sample has a PFU/ml of 1.66 x 10. Assuming a 1:10 dilution series and plating as we did in class, which plate should be the countable plate? In other words, which plate is likely to yield 166 plaques? (d) You have used a phage titer procedure to determine the titer of a phage sample to be 100,000 PFU/ml. You now want to use this phage sample to conduct an experiment, and you need to make sure each trial of the experiment uses the same phage concentration 100 PFU/ml Describe and/or diagram how you will use the original phage sample to prepare a diluted sample with the desired PFU/ml for your experiment. In your description / diagram, you MUST shovw exactly how much phage solution and how much sterile broth you need. 3. Clinical Connection: In the pre-antibiotic era, there was interest in using bacteriophage as a means to treat bacterial infections. After antibiotics were discovered and became widely available, research into bacteriophage therapy fell out of favor in the United States and western Europe. However, active research continued in a number of countries that were part of the former Soviet Union and its easten European satellite nations, and phage therapy is used clinically there today. (2 points)Explanation / Answer
Answer to the first question (no. 1):
Bacteria can be quantitatively estimated by measuring turbidity of the broth (usually measuring optical density at 600 nm). But in case of phage estimation, the phage solution is clear (not turbid) making it unsuitable for turbidity measurement. Phage infects bacteria, replicate itself and finally lyse the bacterial cells. This property can be better harnessed using titer procedure (plaque formation) for phage assay.
Since phage solution lacks turbidity unlike bacterial broth, turbidimetry can not be applied the way used for bacterial estimation.
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