Ch. 6 - Microbial Growth

Tortora - Microbiology: An Introduction 14th Edition

Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook

Tortora 14th Edition

Ch. 6 - Microbial Growth

Problem 3

Chapter 6, Problem 3

Which of the lines best depicts the log phase of a thermophile incubated at room temperature?

Verified step by step guidance

Step 1: Understand the growth phases of bacteria, including the lag phase, log (exponential) phase, stationary phase, and death phase. The log phase is characterized by rapid, exponential growth where the number of cells increases logarithmically over time.

Step 2: Recognize that thermophiles are microorganisms that thrive at high temperatures, typically above 45°C, and their optimal growth is not at room temperature (around 20-25°C). At room temperature, thermophiles will grow very slowly or not at all.

Step 3: Analyze the graph where the y-axis is the log10 of the number of cells and the x-axis is time. Line 'a' shows the steepest increase, indicating rapid growth; line 'b' shows moderate growth; line 'c' is flat, indicating no growth.

Step 4: Since the thermophile is incubated at room temperature, it will not grow rapidly. Therefore, the line that best depicts the log phase under these suboptimal conditions would be the one showing slow or no growth.

Step 5: Conclude that line 'c', which is flat and shows no increase in cell number over time, best represents the log phase of a thermophile incubated at room temperature because the cells are not actively dividing.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Microbial Growth Phases

Microbial growth typically follows distinct phases: lag, log (exponential), stationary, and death. The log phase is characterized by rapid cell division and exponential increase in cell number, shown as a steep upward slope on a growth curve.

Thermophiles and Temperature Effects

Thermophiles are microorganisms that thrive at high temperatures, usually between 45°C and 80°C. Incubating thermophiles at room temperature (around 20-25°C) slows or inhibits their growth, often resulting in a reduced or absent log phase.

Interpreting Growth Curves

Growth curves plot the logarithm of cell number against time to visualize microbial population changes. A steep upward line indicates active growth (log phase), a flat line indicates no growth, and a less steep slope suggests slower growth rates.

Recommended video:

Guided course

08:59

Microbial Growth Curves in a Closed System

Related Practice

Textbook Question

Define and explain the importance of each of the following:

a. Catalase

b. Hydrogen peroxide

c. Peroxidase

d. Superoxide radical

e. Superoxide dismutase

1547

views

Textbook Question

Which of the lines best depicts the log phase of Listeria monocytogenes growing in a human?

950

views

Textbook Question

Seven methods of measuring microbial growth were explained in this chapter. Categorize each as either a direct or an indirect method.

1127

views

Textbook Question

Assume you inoculated 100 facultatively anaerobic cells onto nutrient agar and incubated the plate aerobically. You then inoculated 100 cells of the same species onto nutrient agar and incubated the second plate anaerobically. After incubation for 24 hours, you should have

a. more colonies on the aerobic plate.

b. more colonies on the anaerobic plate.

c. the same number of colonies on both plates.

1910

views

Textbook Question

Describe binary fission.

2166

views

Textbook Question

Macronutrients (needed in relatively large amounts) are often listed as CHONPS. What does each of these letters indicate, and why are they needed by the cell?

1358

views