Brock Biology of Microorganisms (15th Edition)
15th Edition
ISBN: 9780134261928
Author: Michael T. Madigan, Kelly S. Bender, Daniel H. Buckley, W. Matthew Sattley, David A. Stahl
Publisher: PEARSON
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Chapter 5.5, Problem 1CR
Summary Introduction
The nutritional requirements of microorganisms are fulfilled by culture media. A culture medium can be a defined or complex one. The other media like selective, enriched media, differential media are used for specific purposes. Numerous microorganisms can grow in liquid and solid media. Pure cultures are genetic clones developed from a single cell or organism.
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Nutrient Agar (NA) is a general purpose medium used for the cultivation of a wide variety of non-
fastidious microorganisms (Merck, 2000). Its ingredients are listed in Table 2. You are tasked to prepare
300ml of NA, determine the amount of ingredients and write in column 3 in Table 2. Show your
calculations.
*A sample calculation was made for you.
Peptone = 300 ml x 0.5% = 1.5 g
Table 2. Medium Composition of Nutrient Agar (NA) with the recommended proportions (Merck, 2019)
Ingredients
In %
In Grams/300ml
Peptone
0.5
*1.5
Meat extract
0.3
Agar
1.5
Distilled Water
As needed
A microbiologist has isolated a new strain of bacteria, and is trying to characterize aspects of its growth. Three flasks of the same media have different amounts of NaCl added. Other growth conditions are identical, and the flasks inoculated at the same time. At regular intervals over a 3 hour period, culture samples are taken and turbidity is measured. Here are the absorbance values over time in a table and graphed.
Absorbance (OD600)
Time (min)
20% NaCl
3% NaCl
0% NaCl
0
0.05
0.05
0.05
30
0.06
0.05
0.05
60
0.075
0.06
0.05
90
0.11
0.07
0.049
120
0.25
0.1
0.048
150
0.5
0.105
0.055
180
0.7
0.11
0.055
210
0.99
0.15
0.06
240
1.22
0.18
0.055
270
1.35
0.19
0.06
300
1.5
0.2
0.06
330
1.6
0.25
0.062
360
1.7
0.3
0.06
Based on these data, which of the following can be determined about this bacterium?
It is psychrophilic.
It…
A culture medium is comprised of the following components: 0.5% peptone, 0.3% meat extract, 1.5% agar, and distilled water. If you are asked to prepare 765 mL of culture media, how much meat extract would you need?
Chapter 5 Solutions
Brock Biology of Microorganisms (15th Edition)
Ch. 5.1 - Define the term generation. What is meant by the...Ch. 5.1 - How do binary fission and budding cell division...Ch. 5.1 - How does the biofilm growth mode differ from that...Ch. 5.1 - Prob. 1CRCh. 5.2 - What is a semilogarithmic plot and what...Ch. 5.2 - For an exponentially growing culture that...Ch. 5.2 - For testing a bacteriums response to a toxic...Ch. 5.2 - How is the generation time (g) of an exponentially...Ch. 5.3 - In which phase of the growth curve do cells divide...Ch. 5.3 - Prob. 2MQ
Ch. 5.3 - Prob. 3MQCh. 5.3 - Describe the growth cycle of a population of...Ch. 5.4 - How do microorganisms in a chemostat differ from...Ch. 5.4 - What happens in a chemostat if the dilution rate...Ch. 5.4 - Do pure cultures have to be used in a chemostat?Ch. 5.4 - How does a chemostat regulate growth rate and cell...Ch. 5.5 - Why would a complex culture medium for Leuconostoc...Ch. 5.5 - In which medium shown in Table 5.1, defined or...Ch. 5.5 - What is meant by the word sterile? Why is aseptic...Ch. 5.5 - How many cells could be present in a single...Ch. 5.5 - Prob. 1CRCh. 5.6 - What are some of the problems that can arise when...Ch. 5.6 - Using microscopic techniques, how could you tell...Ch. 5.6 - Are total cell counts useful if one does not know...Ch. 5.7 - Why is a viable count more sensitive than a...Ch. 5.7 - Describe how you would dilute a bacterial culture...Ch. 5.7 - Prob. 3MQCh. 5.7 - How does a viable count differ from a total count?Ch. 5.8 - List two advantages of using turbidity as a...Ch. 5.8 - Describe how you could use a turbidity measurement...Ch. 5.8 - How can turbidity be used as a measure of cell...Ch. 5.9 - How does a hyperthermophile differ from a...Ch. 5.9 - Prob. 2MQCh. 5.9 - E. coli can grow at a higher temperature in a...Ch. 5.9 - Examine the graph in Figure 5.17. Why is the...Ch. 5.10 - Prob. 1MQCh. 5.10 - What molecular adaptations to cold temperatures...Ch. 5.10 - Prob. 1CRCh. 5.11 - Which phylogenetic domain includes species with...Ch. 5.11 - How does the membrane structure of...Ch. 5.11 - What is Taq polymerase and why is it important?Ch. 5.11 - How do cells of hyperthermophiles prevent heat...Ch. 5.12 - How does the concentration of H+ change when a...Ch. 5.12 - What terms are used to describe organisms whose...Ch. 5.12 - Prob. 3MQCh. 5.12 - Concerning the pH of the environment and of the...Ch. 5.13 - What is the aw of pure water? What is the lower...Ch. 5.13 - What are compatible solutes, and when and why are...Ch. 5.13 - How does a halophile maintain positive water...Ch. 5.14 - How does an obligate aerobe differ from a...Ch. 5.14 - How does a reducing agent work? Give an example of...Ch. 5.14 - How does Superoxide dismutase or superoxide...Ch. 5.14 - Contrast an aerotolerant and an obligate anaerobe...Ch. 5.15 - Why is heat an effective sterilizing agent?Ch. 5.15 - What steps are necessary to ensure the sterility...Ch. 5.15 - Distinguish between the sterilization of...Ch. 5.15 - Contrast the terms thermal death time and decimal...Ch. 5.16 - Define D10 and explain why the killing dose for...Ch. 5.16 - Prob. 2MQCh. 5.16 - Prob. 3MQCh. 5.16 - Prob. 1CRCh. 5.17 - Distinguish between the antimicrobial effects of...Ch. 5.17 - Describe how the minimum inhibitory concentration...Ch. 5.17 - Distinguish between a sterilant, a disinfectant,...Ch. 5.17 - Describe the procedure for obtaining the minimum...Ch. 5 - A medium was inoculated with 5 106 cells/ml of...Ch. 5 - Escherichia coli but not Pyrolobus fumarii will...Ch. 5 - In which direction (into or out of the cell) will...
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