GTDB Forum

What happend with Betaproteobacteria

What was the criterion for eliminating betaproteobacteria, and grouping their orderes inside gammaproteobacteria?
For example families Burkholderiaceae and Enterobacteriaceae are inside the same class… Is too strange see that now

Hi Vale

The primary criteria in GTDB classification are the inferred reference tree based on 120 markers (bac120 tree) and rank assignment based on relative evolutionary divergence (RED).

Class Betaproteobacteria is stably recovered within the class Gammaproteobacteria, and such relationships have been observed by number of studies before (based on 16S). In addition, RED value of class Betaproteobacteria falls within the range of order rather than class. On this basis, class Betaproteobacteria Garrity et al. 2006 has been united with the class Gammaproteobacteria Garrity et al. 2005, where the latter name has priority. As a nomenclature consequence, Betaproteobacteria is treated as a later heterotypic synonym of Gammaproteobacteria in GTDB.

This taxonomic opinion has been expressed in Parks et al., 2018 (A standardized bacterial taxonomy based on genome phylogeny substantially revises the tree of life - PubMed). Please note that this does not ‘eliminate’ Betaproteobacteria, and the name can be used if this taxon is treated as a separate class.