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Ch. 11 - The Prokaryotes: Domains Bacteria and Archaea
Tortora - Microbiology: An Introduction 14th Edition
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398Not the one you use?Change textbook
Chapter 11, Problem 2

Which of the following does not belong with the others?
a. Enterobacteriales
b. Lactobacillales
c. Legionellales
d. Pasteurellales
e. Vibrionales

Verified step by step guidance
1
Step 1: Identify the taxonomic rank of each term. All options (Enterobacteriales, Lactobacillales, Legionellales, Pasteurellales, Vibrionales) are names of bacterial orders, which is a rank in the classification hierarchy below class and above family.
Step 2: Determine the bacterial class to which each order belongs. For example, Enterobacteriales, Pasteurellales, and Vibrionales belong to the class Gammaproteobacteria, while Lactobacillales belongs to the class Bacilli, and Legionellales also belongs to Gammaproteobacteria.
Step 3: Compare the classes of each order to find the one that differs from the others. Since most orders listed belong to Gammaproteobacteria except Lactobacillales, which belongs to Bacilli, this indicates a difference in their higher taxonomic classification.
Step 4: Confirm that Lactobacillales is the only order from the class Bacilli, while the others are from Gammaproteobacteria, making it the odd one out.
Step 5: Conclude that the order which does not belong with the others is Lactobacillales because it is from a different bacterial class.

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Key Concepts

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

Bacterial Taxonomy and Classification

Bacterial taxonomy organizes bacteria into hierarchical groups based on genetic and phenotypic similarities. Orders like Enterobacteriales, Lactobacillales, Legionellales, Pasteurellales, and Vibrionales represent different taxonomic ranks within the class Gammaproteobacteria or other classes, helping to categorize bacteria by evolutionary relationships.
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Gammaproteobacteria and Their Orders

Gammaproteobacteria is a diverse class of Gram-negative bacteria containing several orders such as Enterobacteriales, Legionellales, Pasteurellales, and Vibrionales. These orders share common traits like cell wall structure and metabolic features, distinguishing them from other bacterial classes like Bacilli, which includes Lactobacillales.
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Differences Between Gram-Positive and Gram-Negative Bacteria

Gram-positive bacteria, such as those in the order Lactobacillales, have thick peptidoglycan cell walls and stain purple in Gram staining. In contrast, Gram-negative bacteria, including Enterobacteriales and others listed, have thinner walls and an outer membrane, staining pink. This fundamental difference affects classification and physiological traits.
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