Proteobacteria - Taxonomy

Taxonomy

The group is defined primarily in terms of ribosomal RNA (rRNA) sequences. The Proteobacteria are divided into six sections, referred to by the Greek letters alpha through zeta, again based on rRNA sequences. These are often treated as classes. The alpha, beta, delta, epsilon sections are monophyletic, bar the Gammaproteobacteria due to the Acidithiobacillus genus is paraphyletic to Betaproteobacteria, according to multigenome alignment studies, which if done correctly are more precise than 16S (note that Mariprofundus ferrooxydans sole member of the Zetaproteobacteria was previously misclassified on NCBI taxonomy). Acidithiobacillus contains 5 species and the sole genus in its order Acidithiobacillales The divisions of the proteobacteria were once regarded as subclasses (e.g. α-subclass of the Proteobacteria), but are now regarded as classes (e.g. the Alphaproteobacteria).

• Alphaproteobacteria
• Betaproteobacteria
• Gammaproteobacteria
• Deltaproteobacteria
• Epsilonproteobacteria
• Zetaproteobacteria