Reference Work Entry

The Prokaryotes

pp 3-37

Introduction to the Proteobacteria

  • Karel Kersters
  • , Paul De Vos
  • , Monique Gillis
  • , Jean Swings
  • , Peter Vandamme
  • , Erko Stackebrandt


Within the domain Bacteria, the phylum Proteobacteria constitutes at present the largest and phenotypically most diverse phylogenetic lineage. In 1988, Stackebrandt et al. named the Proteobacteria after the Greek god Proteus, who could assume many different shapes, to reflect the enormous diversity of morphologies and physiologies observed within this bacterial phylum. In 2002, the Proteobacteria consist of more than 460 genera and more than 1600 species, scattered over 5 major phylogenetic lines of descent known as the classes “Alphaproteobacteria,” “Betaproteobacteria,” “Gammaproteobacteria,” “Deltaproteobacteria” and “Epsilonproteobacteria.” The Proteobacteria account for more than 40% of all validly published prokaryotic genera and encompass a major proportion of the traditional Gram-negative bacteria, show extreme metabolic diversity, and are of great biological importance, as they include the majority of the known Gram-negatives of medical, veterinary, ind ...

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