A phage-infected bacterial culture was subjected to a series ofdilutions, and a plaque assay was performed in each case, withthe following results. What conclusion can be drawn in the caseof each dilution? Dilution Factor Assay Results(a) 104 All bacteria lysed(b) 106 14 plaques(c) 108 0 plaques
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A phage-infected bacterial culture was subjected to a series of
dilutions, and a plaque assay was performed in each case, with
the following results. What conclusion can be drawn in the case
of each dilution?
Dilution Factor Assay Results
(a) 104 All bacteria lysed
(b) 106 14 plaques
(c) 108 0 plaques
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- A phagehunter performs a spot titer using standard techniques (3 ul of each dilution spotted to lawn) of a lysate obtained from an optimum webbed plate experiment. The phagehunter counts 4 plaques on the 10-8 dilution spot. Which of the following scenarios is the best choice for the phagehunter to do next? a.) The phagehunter has not achieved a high enough titer lysate to move forward with characterization experiments, so they should try to make more optimum webbed plates. b.) The phagehunter has not achieved a high enough titer lysate to move forward with characterization experiments, so they should adopt a phage from direct isolation. c.) The phagehunter has achieved a high enough titer lysate to move forward with characterization experiments. d.) The phagehunter has not achieved a high enough titer lysate to move forward with characterization experiments, so they should go back to the pick-a-plaque experiment.In the ELISA, the pH the coating buffer was 9.6 whereas the pH of the sample buffer (PBS based) was 7.4 a) Why was the pH of the coating buffer so different?b) What is “coating buffer” for an ELISA? Does the buffer molecule usedmake sense based on the desired pH?In an ELISA procedure the samples are incubated and the ELISA plate iscovered with parafilm and placed in a humidified chamber to preventevaporation of the small liquid volumes in the wells.c) How would your results change if you did not incubate in a humidifiedchamber?A phagehunter performs a spot titer using standard techniques (3 ul of each dilution spotted to lawn) of a lysate obtained from an optimum webbed plate experiment. The phagehunter counts 8 plaques on the 10-7 dilution spot. Which of the following scenarios is the best choice for the phagehunter to do next? a.) The phagehunter has not achieved a high enough titer lysate to move forward with characterization experiments, so they should go back to the pick-a-plaque experiment. b.) The phagehunter has not achieved a high enough titer lysate to move forward with characterization experiments, so they should adopt a phage from direct isolation. c.) The phagehunter has not achieved a high enough titer lysate to move forward with characterization experiments, so they should try to make more optimum webbed plates. d.) The phagehunter has achieved a high enough titer lysate to move forward with characterization experiments.
- 3) Were all of the conditions of a standardized Kirby-Bauer test met as you performed this assay? If not, which were not? 4) What is the significance of colonies that develop within otherwise clear zones of inhibition? If the laboratory report for one of your patients indicated colonies within the zone, what concerns would you have for your patient?In lab we learned a technique that helped us to visulize individual colonies of bacter 1. Describe this technique. 2. What do you expect the resutls to look like? Be specific. 3. How can this technique help you to determine if your culture is contaminated? For the toolbar, press ALT+F10 (PC) or ALT+FN+F10 (Mac). BIUS Paragraph I +] F H Ix X ABC † ( O K₂ KN Q V Arial sè "Ω Θ A 4 10pt EE 88 A Click Save and Submit to save and submit. Click Save All Answers to save all answers. 描く前 X² X₂ 3 由用目a. Explain whether or not any of the methods in fi gure 2.9 could beused to determine the total number of cells present in a patient’s specimen.b. After performing the streak plate method on a bacterial specimen, theculture was incubated for 48 hours at 37°C. Upon viewing the plate, therewas heavy growth (with no isolated colonies) in the fi rst quadrant, but nogrowth was apparent in the remaining quadrants. Please discuss errors in the procedure that could have produced this result.
- You want to subculture your cells from T25 flask to 96-well plates. You first collected your cells in a tube with 5ml of culture medium. Then carried out a trypan blue assay and counted your cells with a hematocytometer as shown in Figure below. Answer the questions according to the results: a. Calculate the concentration of the stock including the dead and living cells. Dont forget to show the units! b. Calculate the percentage (%) of the living cells in the stock. c. You want to seed 6000 living cells into each well of 96 well plates, then calculate the volume you should take from the stock for each well. 輯 1 mm I IREA phagehunter performs a full plate titer using standard techniques (100 ul of each dilution added to 250 ul of Gordonia terrae cells) of a lysate obtained from an optimum webbed plate experiment. The phagehunter counts 72 plaques on the 10-7 dilution plate. Which of the following scenarios is the best choice for the phagehunter to do next? a.) The phagehunter has not achieved a high enough titer lysate to move forward with characterization experiments, so they should adopt a phage from direct isolation. b.) The phagehunter has not achieved a high enough titer lysate to move forward with characterization experiments, so they should go back to the pick-a-plaque experiment. c.) The phagehunter has achieved a high enough titer lysate to move forward with characterization experiments. d.) The phagehunter has not achieved a high enough titer lysate to move forward with characterization experiments, so they should try to make more optimum webbed plates.You have conducted serial 10-fold dilutions and measured the cfu (colony forming units) of a Streptococcus pneumoniae culture and also the pfu (plaque forming units) of a phage (virus) that infects the bacteria. You counted 5 cfu in a 0.4 ml sample of a 106 dilution of the bacterial sample. You then counted 50 plaque-forming units (pfu) in a 0.25 ml sample of a 108 diluted sample of the phage culture. What are the cfu/ml of the S. pneumoniae and pfu/ml of the phage cultures before dilution? 5 x 106 cfu/ml and 2 x 109 pfu/ml 4 x 107 CFU/ml and 2 x 109 PFU/ml 1.25 x 108 cfu/ml and 10 x 1010 pfu/ml 1.25 x 107 cfu/ml and 2 x 1010 pfu/ml
- A bacterial culture was grown for 12 hours. At 4-hour interval, the culture was sampled to determine the population of the culture, by transferring 25 ml of the suspension to 225 ml 0.90% NaCl. Three consecutive dilutions were further made by using I ml aliquot in 9 ml of 0.90% NaCl. One ml from each dilution was plated in each of duplicate plates. The following table shows the results of the plating method. 田 Sampling COUNTS 1st dilution 54; 61 2nd dilution 3rd dilution 4h dilution 1st 3; 7 0; 0 0,0 2nd TNTC TNCT 242: 233 28: 37 3rd TNTC TNTC INTC 249-246 * TNTC = Too numerous to count i. Illustrate the dilution series used and label the final dilution of each dilution. ii. Determine the bacterial count (CFU/ml) every 4 hours of incubation for 12 hours. Show all computations.A serial dilution of overnight E.coli culture was performed by pipetting 1ml of a bacterial culture into a 9 ml LB medium. After this, from 10-4 and 10-5 dilution tubes 100µl were plated onto LB agar plates. Upon overnight incubation at 37°C, 200 colonies were counted in 10-4 and 22 colonies were present on 10-5 plates. How many colony-forming units were present per ml of the original culture? If the formula for CFU/ml =no. Of colonies/dilution factor*volume of culture plateThe following pictures show the results of a Disk Diffusion Assay for different types of bacteria. For each bacteria, what antibiotic would you recommend be used on the patient? Explain your choice.