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Ch. 6 - Microbial Growth
Tortora - Microbiology: An Introduction 14th Edition
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook
All textbooksTortora 14th EditionCh. 6 - Microbial GrowthProblem 8
Chapter 6, Problem 8

Which of the following is not a characteristic of biofilms?
a. Antibiotic resistance
b. Hydrogel
c. Iron deficiency
d. Quorum sensing

Verified step by step guidance
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Step 1: Understand what a biofilm is. A biofilm is a structured community of microbial cells enclosed in a self-produced polymeric matrix and adherent to an inert or living surface.
Step 2: Review the characteristics of biofilms. Common features include antibiotic resistance due to the protective matrix, the presence of a hydrogel-like extracellular polymeric substance (EPS), and quorum sensing, which is cell-to-cell communication that regulates gene expression in response to population density.
Step 3: Analyze each option in the context of biofilm characteristics: (a) Antibiotic resistance is typical because biofilms protect bacteria from antibiotics; (b) Hydrogel refers to the EPS matrix that holds the biofilm together; (c) Iron deficiency is not a characteristic of biofilms themselves but rather a condition that might affect bacterial growth; (d) Quorum sensing is a key mechanism in biofilm formation and maintenance.
Step 4: Identify the option that does not fit as a characteristic of biofilms. Since iron deficiency is not inherently a feature of biofilms but rather an environmental or physiological condition, it is the correct choice.
Step 5: Conclude that the answer is the option that does not describe a biofilm characteristic, which is iron deficiency.

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Key Concepts

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

Biofilm Structure and Composition

Biofilms are communities of microorganisms attached to surfaces, embedded in a self-produced matrix called a hydrogel. This matrix protects the cells and helps maintain the biofilm’s structural integrity.
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Antibiotic Resistance in Biofilms

Microorganisms within biofilms exhibit increased resistance to antibiotics compared to free-floating cells. This resistance arises from limited drug penetration, altered microenvironment, and protective mechanisms within the biofilm.
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Quorum Sensing in Biofilms

Quorum sensing is a cell-to-cell communication process that bacteria use to coordinate gene expression based on population density. It regulates biofilm formation, maintenance, and dispersal by controlling collective behaviors.
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Related Practice
Textbook Question

Which of the following is true about the optimum growth temperature of most mesophiles?

a) They can grow well at 37^0C.

b) They are more likely to grow at refrigerator temperatures.

c) They can strive well in extremely high temperatures.

d) All of the above.

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Textbook Question

Which of the following types of media would not be used to culture aerobes?

a. Selective media

b. Reducing media

c. Enrichment media

d. Differential media

e. Complex media

Textbook Question

An organism that has peroxidase and superoxide dismutase but lacks catalase is most likely an

a. aerobe.

b. aerotolerant anaerobe.

c. obligate anaerobe.

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Textbook Question

Which one of the following temperatures would most likely kill a mesophile?

a. -50℃

b. 0℃

c. 9℃

d. 37℃

e. 60℃

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Textbook Question

Nitrogen and phosphorus added to beaches following an oil spill encourage the growth of natural oil-degrading bacteria. Explain why the bacteria do not grow if nitrogen and phosphorus are not added.

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Textbook Question

Differentiate complex and chemically defined media.

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