A serial dilution was performed for a viable count of bacteria. The original bacterial cuture contained 100.000 celts el Three diution tubes each containing 9.0 ml of nutrient broth were used.1 miof cells was transferred between tubes 1 mi from the third tube was plated on an gar plate The number of colonies expected on the plate is Oa 1000 Ob. 10 Oc 10.000 Od 100

A serial dilution was performed for a viable count of bacteria. The original bacterial cuture contained 100.000 celts el Three diution tubes each containing 9.0 ml of nutrient broth were used.1 miof cells was transferred between tubes 1 mi from the third tube was plated on an gar plate The number of colonies expected on the plate is Oa 1000 Ob. 10 Oc 10.000 Od 100

Microbiology for Surgical Technologists (MindTap Course List)

2nd Edition

ISBN:9781111306663

Author:Margaret Rodriguez, Paul Price

Publisher:Margaret Rodriguez, Paul Price

Chapter4: The Prokaryotes

Section: Chapter Questions

Problem 3UTM: A surgical technologist working in the Central Sterile Processing Department is asked to run the...

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A sample of water was enumerated using a counting chamber (haemocytometer) and 220 bacterial cells were counted in 25 small squares (each of volume 2.5 x 10-7 cm3). Viable counts were carried out on the same culture using both the pour plate method (incorporating 1 mL samples of a range of dilutions into plate count agar plates) and the Miles & Misra spread plate method, where 0.02 mL samples were spread on sectors of a plate count agar plate. For the pour plate count the average of triplicate samples was 178 colonies per plate of the 10-4dilution. For the Miles and Misra count the average of triplicate samples was 21.3 colonies per sector of the 10-4 dilution. Calculate the total count and the viable pour plate and spread plate counts and suggest possible reasons for the difference between the three different counts.
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?
You are given a 1 gram soil sample of unknown bacterial load. After doing 10-fold serial dilutions of the soil in sterile water, 100 uL volumes are taken from each dilution for preparation of pour plates. Following incubation, each half of the 10-8 plate has 46 colonies.a) What was the dilution factor?b) How many bacteria were present in the soil?2. Staphylococcus aureus divides every 20 minutes. A culture begins with 10 bacterial cells.a) After 5 hours, how many generations have occurredb) After 5 hours, how many bacteria are present?3. How many milliliters would you need to prepare a 10-2 dilution from a 10ml starting culture?
A culture of Staphylococcus is diluted as follows:(1) 20mL are added to 80mL of water.(2) 10uL from (1) are then added to 9.99mL of water.(3) A 10-2 dilution is made from tube # (2).(4) 100uL from (3) are plated for a pour plate and incubated. There were 34 colonies counted on one quarter of the plate following incubation. a) What was the overall dilution?b) How many cfu/mL were present in the original culture?
A laboratory technician performed a series of 10 fold serial dilutions shown below. he plated 0.1 mL from each dilution tube onto NA and got the follow numbers per plate dilution 1:10 1:10 1:100 1:1000 1:10000 1:100000 colony count >1000 >1000 808 303 38 3 calculate the concentration of bacteria in the undiluted stock (in CFU/mL)
thirty-six colonies grew on nutrient agar plates when 1.0ml of a 1/10 dilution of a water sample was plated using the standard plate count methodology. How many bacteria were in the original water sample? a.4/ml b.36000/ml c.360/ml d.36/ml e.3600/ml
1. You are given a 1 gram soil sample of unknown bacterial load. After doing 10-fold serial dilutions of the soil in sterile water, 100 uL volumes are taken from each dilution for preparation of pour plates. Following incubation, you are observing the growth of the plate prepared from the 10-8 plate. You divide the plate into two equal parts and count 46 colonies in each half.a) What was the dilution factor?b) How many total colonies were on the plate?c) Was your count valid?d) How many bacteria were present in the soil sample?
To determine the number of cells in a pure culture of Klebsiella pneumoniae, you have performed a serial dilution using three tubes of sterile saline (9.9 ml each). A sample of 0.1 ml from the culture was added to tube 1. Similarly, 0.1 ml from tube 1 was used to inoculate tube 2, and tube 3 was inoculated using 0.1 ml from tube 2. A nutrient agar plate was then inoculated using 0.1 ml from tube 3 and incubated overnight. The next day, 92 colonies were observed on the plate. How many cfu/ml were in the original culture? Using a Petroff-Hauser counting chamber, the number of cells in the same culture was estimated to be 8.5 • 109 cells/ml. How can you explain these results?
A bacterial culture has a concentration of 3.2 x 108 cells /mL. You dilute this culture as follows: 1/50, then 10-3and finally 1/20. If you then plate 0.2 mL of the final dilution, how many CFU would you expect following incubation?
answer the following questions with book reference. 1. What is meant by a bacterial “colony” or colony-forming unit? 2. Why are colonies that develop on a heavily seeded plate smaller than those that appear on a sparely seeded plate? 3. What are some of the uses and advantages of the ff.:a. Agar plateb. Agar slantc. Broth culture 4. What are the advantages and limitations of studying bacteria by means of the Culture method? 5. Why is it desirable that most cultures be inspected after 15 to 18 hours of incubation? 6. Why should culture media after inoculation be incubated at an optimal temperature immediately? 7. Describe other types of aerobic jars and anaerobic methods.
The students of a Microbiology class were tasked to transfer or subculture a pure culture of Escherichia coli bacterium in five 7 mL nutrient broth and five petri dishes of nutrient agar with 20 mL capacity each. Based on the instruction bottles for nutrient broth and nutrient agar, preparation of the culture media is as follows. Nutrient broth: 8 g/liter Nutrient agar: 28 g/liter Answer the following: a. What is the weight in grams of nutrient broth? b. What is the weight in grams of nutrient agar? c. What is the distilled water in mL for nutrient broth? d. What is the distilled water in mL for nutrient agar?
What was the concentration of bacteria (CFU/mL) in the original suspensions used for dilutions and plating below: Dilution Amount plated # of colonies counted 10-4 1.0 mL 271 10-5 0.1 mL 36 10-6 1.0 mL 9