Proteobacteria

Proteobacteria is a major group (phylum) of bacteria. They include a wide variety of pathogens, such as Escherichia, Salmonella, Vibrio, Helicobacter, Yersinia, Legionellales, and many other notable genera. Others are free-living (non-parasitic) and include many of the bacteria responsible for nitrogen fixation.

Classification

Proteobacteria are divided into six classes with the last two being non-validated: Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Epsilonproteobacteria, Zetaproteobacteria, Oligoflexia, and Acidithiobacillia.

Characteristics

Proteobacteria are Gram-negative bacteria with an outer membrane mainly composed of lipopolysaccharides. Many move about using flagella, but some are non-motile or rely on bacterial gliding. The latter include the myxobacteria, an order of Deltaproteobacteria that produce multicellular fruiting bodies. Also, a wide variety in the types of metabolism exists. Most members are facultatively or obligately anaerobic, chemoautotroph, and heterotrophic, but numerous exceptions exist.

History

The group is defined primarily in terms of ribosomal RNA (rRNA) sequences. The Proteobacteria are divided into nine classes with the last two being non-validated: Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Epsilonproteobacteria, Zetaproteobacteria, Oligoflexia, Acidithiobacillia, and Thermodesulfovibrionia.

See also

• Bacterial taxonomy
• Microbiology

External links

• LPSN - List of Prokaryotic names with Standing in Nomenclature

Proteobacteria Resources
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