MicrobiologyLesson 2 of 6 in the course Prokaryotic Diversity

Proteobacteria: Classes, Lifestyles, and Representative Genera

5 flashcards · 5 quiz questions · 5 match pairs · 4 fill-in sentences · English

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Summary

Proteobacteria is a broad phylum of gram-negative bacteria that includes organisms with widely varied lifestyles, from nutrient-poor-environment specialists to important human pathogens. This lesson introduces the phylum and focuses on Alphaproteobacteria.

In 1987, microbiologist Carl Woese proposed grouping “purple bacteria and their relatives” as a distinct bacterial phylum based on similarities in genome nucleotide sequences. The group was later named Proteobacteria. It is a diverse phylum of gram-negative bacteria that includes members of the normal human microbiota as well as many pathogens.

All flashcards

What are the five classes of Proteobacteria?
Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, and Epsilonproteobacteria.
What is an oligotroph?
An organism adapted to environments with very low nutrient levels.
Why are Rickettsia obligate intracellular bacteria?
They require host cells for part of their life cycle and cannot make their own ATP.
What does Bordetella pertussis do to the respiratory tract?
Its toxins paralyze respiratory cilia and damage respiratory cells.
How does Helicobacter pylori adapt to the acidic stomach?
It produces urease and other enzymes that make its local environment less acidic.

Quiz questions

  1. What evidence did Carl Woese use to propose Proteobacteria as a distinct bacterial group?Answer: Similarities in the groups’ genome nucleotide sequences.
  2. Which medium is commonly used to cultivate Neisseria in the laboratory?Answer: Chocolate agar containing partially hemolyzed red blood cells.
  3. How do coliform bacteria differ from noncoliform enteric bacteria in lactose fermentation?Answer: Coliforms produce both acid and gas from lactose.
  4. Where does Bdellovibrio feed while infecting a gram-negative bacterial host?Answer: In the host’s periplasm, between its plasma membrane and cell wall.
  5. Which description best matches Vibrio cholerae toxin activity?Answer: It causes the intestine to secrete large amounts of water and electrolytes.

Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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