1. 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 1 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.

1. 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 1 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.

Basic Clinical Laboratory Techniques 6E

6th Edition

ISBN:9781133893943

Author:ESTRIDGE

Publisher:ESTRIDGE

Chapter7: Basic Clinical Microbiology

Section7.4: The Gram Stain

Problem 5RQ

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1. A bacterial culture was grown for 12 hours. At 4-hour interval, the culture was sampled to determine the population ofthe culture, by transferring 25 mlof the suspension to 225 ml 0.90% NaCl. Three consecutive dilutions were further made by using 1 mlaliquot in 9 mlof 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. EDI Sampling COUNTS 1st dilution 54; 61 TNTC 2nd dilution 3; 7 TNCT TNTC 3rd dilution 0; 0 242; 233 TNTC 4th dilution 0, 0 28: 37 249;246 1st 2nd 3rd TNTC * TNTC = Too numerous to count i. Determine the bacterial count (CFU/ml) every 4 hours of incubation for 12 hours. Show all computations. a. 1s* Sampling b. 2d Sampling c. 3* Sampling
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 pure bacterial culture of unknown concentration was diluted to determine the concentration of viable bacteria in the original culture. Serial dilutions were performed as 2. diagrammed below. A volume of 500 µl was transferred into each tube. TSA plates were inoculated with 100 µl from the last three dilution tubes. a. If the dilution between each tube is 102, what is the volume of diluent in each of the 5 dilution tubes? Provide the volume using ml as the units. b. What is the total dilution of tube number 4? Express the total dilution using scientific notation. c. What is the concentration of viable bacteria in the original culture? Express the concentration using scientific notation and CFU/ml as the units. d. If you inoculated a TSA plate with 1.0 ml from dilution tube 4, how many colonies would you expect to form on the plate after incubation? e. If the original culture had a volume of 50ml, what was the total number of viable bacteria in the 50 ml of the original culture? 1 2 3…
Assuming that serial dilution was carried out in a laboratory experiment in 6 tubes with 9 ml of saline in each tube and 0.1ml of the stock solution was used for initial dilution, pour plate method of inoculation was performed after the dilution process using 1ml of the culture from the samples from the test tubes. It was found out that on the 6th Petri dish after incubation, there was a total of 16 individual colonies counted. Compute the total number of microorganisms present in tube one, assuming that there was no human error in the transferring proces.
assuming that serial dilution was carried out in a laboratory experiment in 6 tubes with 9 ml of saline in each tube and 0.1ml of the stock solution was used for initial dilution, pour plate method of inoculation was performed after the dilution process using 1ml of the culture from the samples from the test tubes. It was found out that on the 6th Petri dish after incubation, there was a total of 16 individual colonies counted. Compute the total number of microorganisms present in tube one, assuming that there was no human error in the transferring process.
Five ml of bacterial culture is added to 45 ml of sterile diluent. From this suspension, the following serial dilutions were made, two 1:100 and one 1:10 dilutions, and 0.1 ml is plated onto Plate Count Agar from the last dilution. After incubation, 186 colonies were counted on the plate. 1. What is the dilution factor, or how much of the original sample was diluted?
A pure bacterial culture of unknown concentration was diluted to determine the concentration of viable bacteria in the original culture. Serial dilutions were performed as 2. diagrammed below. A volume of 500 µl was transferred into each tube. TSA plates were inoculated with 100 µl from the last three dilution tubes. d. If you inoculated a TSA plate with 1.0 ml from dilution tube 4, how many colonies would you expect to form on the plate after incubation? e. If the original culture had a volume of 50ml, what was the total number of viable bacteria in the 50 ml of the original culture? 2 3 240 3 Number of colonies
You are given a bacterial culture which has a concentration of approximately 5.0 x 10^8 cells/mL. List a series of dilutions and platings that you could carry out in order to determine the exact concentration of the culture. Note that you must plate four plates from a minimum of two dilution tubes. The volumes plated should be in the range of 0.1 mL – 1.0 mL. Duplicate volumes may not be plated from any one dilution tube. Each plating should aim for a count between 30 and 300 CFUs. You can select any value from 30-300 for CFU and any volume from 0.1-1.0 to find out dilution scheme
Ten grams of hamburger were added to 90 mL of sterile buffer. This was mixed well in a blender. One-tenth of amL of this slurry was added to 9.9 mL of sterile buffer. After thorough mixing, this suspension was further dilutedby successive 1/100 and 1/10 dilutions. One-tenth of a mL of this final solution was plated onto Plate Count agar.After incubation 145 colonies were present. How many colony-forming units were present in the total 10 gramsample of hamburger?
A pure bacterial culture of unknown concentration was diluted to determine the concentration of viable bacteria in the original culture. Serial dilutions were performed as 1. diagrammed below. Each dilution tube contained 400 ul of diluent and 100 ul was transferred into each tube. TSA plates were inoculated with 100 µul from the last three dilution tubes. a. What is the dilution between each tube shown in the diagram below? Express your answer as a ratio. b. What is the total dilution of tube number 5? Express your answer as a ratio. c. What is the concentration of viable bacteria in the original culture? Express your answer using scientific notation and the units CFU/ml. d. What is the concentration of viable bacteria in tube number 2? Express your answer using the units CFU/ml. e. If you inoculated a TSA plate with 250 µl from tube number 5, how many colonies would you expect to see after the plate was incubated? 1 2 3 5 423 80 13 Number of colonies
Five mL of bacterial culture is added to 45 mL of sterile diluent. From this suspension, the following serial dilutions were made, two 1:100 and one 1:10 dilutions, and 0.1 mL is plated onto Plate Count Agar from the last dilution. After incubation, 186 colonies were counted on the plate
1. Sally Monella found 344 bacterial colonies on one of her plates. She had prepared this plate after a serial dilution of a culture of Yersinia pestis. She had pipetted 1 ml sample of diluted Yersinia pestis from a tube with the overall dilution factor of 106 into a plate and covered it with agar. She used this plate to calculate the concentration in cells/ml of a bacterial culture. a) How many organisms were in the original culture? b) Were her results valid? Why or why not?