Laboratory Experiments in Microbiology (11th Edition)
11th Edition
ISBN: 9780321994936
Author: Ted R. Johnson, Christine L. Case
Publisher: PEARSON
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Chapter 22, Problem 1CA
The source of Legionella causing hospital-acquired pneumonia has been linked to hospital water supplies. In healthcare settings, hot water coming out of the faucet should not be hotter than
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This is the growth curve for Clostirdium (incubated under optimal growth conditions). Use it to answer the following questions.
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Cell concentration (million cells/ml)
2.5
2
0.2
1.5
1
0.5
0
2
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lag
log
0.25
4
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units
6
million of cells per ml
(Image description.: Horizontal axis is time in hours, Vertical is cell concentration in millions of cells per ml. Curve starts at 0,0, increases by 4
hours to 0.5 million cells/ml, goes up steeply over two hours from 0.5 million/ml at 4 hours to 2.5 million cells/ml at 8 hours, 8-12 hour shows
an increase of 0.3 to 2,8 million cellls/ml and last 2 hours is flat at 2.8million cells/ml.)
From 12 hr to 14 hr is called
phase.
lunar
2
8
Time (hours)
10
5
stationary
12
cells
14
death
16
million of cells per ml per hour
hours
million of cells
A culture of S. cerevisea has an overnight OD of 4.5
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You will be plating 100µl onto agar and want the final count of colonies on the plate to be around 300 colonies.
How much of the 4.5 OD culture must you use to get a 500µl subdilution (with sterile water), so that you have diluted enough to get approx 300 colonies per 100ul
A batch of turkey rolls (10 lb—approximately 4.5 Kg—each) were cooked to 165°F internal temperature in bags, opened, sliced, vacuum-packaged, and stored at 40°F. The product was expected to have a refrigerated shelf life of 50 days. However, after 40 days, the packages contained gas and approximately 107 bacterial cells/g of meat. The bacterial species involved in the spoilage was found to be Leuconostoc carnosum, which is killed at 165°F. What could be the sources of the bacterial species in this cooked product?
Chapter 22 Solutions
Laboratory Experiments in Microbiology (11th Edition)
Ch. 22 - Prob. 1QCh. 22 - Prob. 2QCh. 22 - Give an example of a nonlaboratory use of each of...Ch. 22 - Define the term pasteurization. What is the...Ch. 22 - Explain why fungi and Bacillus sometimes grow...Ch. 22 - Assume that a DRT value for autoclaving a culture...Ch. 22 - Indicators are used in autoclaving to ensure that...Ch. 22 - A biological indicator used in autoclaving is a...Ch. 22 - The source of Legionella causing...
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