Laboratory Experiments in Microbiology (11th Edition)
11th Edition
ISBN: 9780321994936
Author: Ted R. Johnson, Christine L. Case
Publisher: PEARSON
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Textbook Question
Chapter 7, Problem 4Q
Which step can you omit without affecting determination of the Gram reaction?
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Suppose your Professor handed you a test tube with 2.0mL of E.coli broth culture and told you to make a 10-1 dilution of the ENTIRE culture. Explain how you would do this.
You have several different media onto which you inoculated eight strains of yeast (A-H). The media
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with one vitamin. Of the yeast strains, one is a prototroph and seven are auxotrophs for a vitamin.
After overnight incubation, the following results were observed (tan patches represent growth):
D
plate 1
(A) B
DE F
GH
plate 5
plate 4
plate 6
Which plate contains an unsupplemented minimal medium? [Select]
Which plate contains a rich medium? [Select]
plate 2
Which strain is a prototroph? [Select]
Strain E is an auxotroph for niacin. Which plate reveals this specific auxotrophy?
[ Select]
plate 3
plate 7
One strain is an auxotroph for both choline and pantothenic acid. Which one is this most likely to
be? [Select]
The following data were obtained by incubating gram-positive bacteria in nutrient medium +
disinfectant for 24 hours, then transferring one loopful to nutrient medium (subculturing). (+ =
growth; - = no growth.
a. Table 7.3, which disinfectant is the most effective at stopping bacterial growth?
How can you tell?
b. In Table 7.3, which disinfectant was bactericidal? How can you tell?
c. In Table 7.3, which disinfectant was most effective against Salmonella? How can
you tell? [Hint: look up Salmonella]
Table 7.3
K.O.
Subculture
Doom
Dilution
Initial
Subculture
Initial
1:16
1:32
1:64
1:128
Mortum
Sterl
Dilution
Initial
Subculture
Initial
Subculture
1:16
1:32
1:64
1:128
Chapter 7 Solutions
Laboratory Experiments in Microbiology (11th Edition)
Ch. 7 - Why do gram-positive cells more than 24 hours old...Ch. 7 - Can iodine be added before the primary stain in a...Ch. 7 - Prob. 3QCh. 7 - Which step can you omit without affecting...Ch. 7 - Suppose you performed a Gram stain on a sample...Ch. 7 - Prob. 2CTCh. 7 - Human cells can be stained with crystal violet and...Ch. 7 - Considering that it isnt possible to identity...
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