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Proteobacteria

Written by the Fiveable Content Team • Last updated August 2025
Written by the Fiveable Content Team • Last updated August 2025

Definition

Proteobacteria are a major phylum of Gram-negative bacteria that includes a wide variety of pathogenic and non-pathogenic species. They are characterized by their diverse metabolic capabilities and roles in various environments.

5 Must Know Facts For Your Next Test

  1. Proteobacteria are classified into six classes: Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Epsilonproteobacteria, and Zetaproteobacteria.
  2. Many Proteobacteria are capable of nitrogen fixation, which is crucial for converting atmospheric nitrogen into a form usable by plants.
  3. Proteobacteria include notable pathogens such as Escherichia coli, Salmonella, and Helicobacter pylori.
  4. They exhibit a wide range of metabolic diversity including phototrophy, lithotrophy, and heterotrophy.
  5. Proteobacteria play vital roles in the human microbiome, particularly in the gut and respiratory tract.

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