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Ch. 7 - The Control of Microbial Growth
Tortora - Microbiology: An Introduction 14th Edition
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook
All textbooksTortora 14th EditionCh. 7 - The Control of Microbial GrowthProblem 1
Chapter 7, Problem 1

Which of the following does not kill endospores?
a. Autoclaving
b. Incineration
c. Hot-air sterilization
d. Pasteurization
e. All of the above kill endospores

Verified step by step guidance
1
Step 1: Understand what endospores are — they are highly resistant structures formed by certain bacteria to survive extreme conditions, including heat, desiccation, and chemicals.
Step 2: Review each method's ability to kill endospores: Autoclaving uses pressurized steam at high temperatures, which is known to effectively kill endospores.
Step 3: Incineration involves burning at very high temperatures, which destroys all microbial life including endospores.
Step 4: Hot-air sterilization uses dry heat at high temperatures for a longer time and is also effective against endospores.
Step 5: Pasteurization involves heating to moderate temperatures for a short time, primarily to reduce microbial load but does not reliably kill endospores.

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Key Concepts

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

Endospore Resistance

Endospores are highly resistant dormant structures formed by some bacteria to survive extreme conditions. They can withstand heat, desiccation, chemicals, and radiation, making them difficult to kill with standard sterilization methods.
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Sterilization Methods and Their Efficacy

Different sterilization techniques vary in their ability to kill microorganisms. Autoclaving uses pressurized steam to achieve high temperatures that destroy endospores, while incineration burns them completely. Hot-air sterilization requires longer exposure at high temperatures to kill spores effectively.
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Pasteurization and Its Limitations

Pasteurization involves heating liquids to moderate temperatures to reduce microbial load but does not reach levels sufficient to kill endospores. It is primarily used to destroy vegetative pathogens, not the highly resistant endospores.
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Related Practice
Textbook Question

Which of the following is most effective for sterilizing mattresses and plastic Petri dishes?

a. Chlorine

b. Ethylene oxide

c. Glutaraldehyde

d. Autoclaving

e. Nonionizing radiation

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Textbook Question

The thermal death time for a suspension of Bacillus subtilis endospores is in dry heat and less than in an autoclave. Which type of heat is more effective? Why?

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Textbook Question

If pasteurization does not achieve sterilization, why is pasteurization used to treat food?

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