suggests that Gracilicutes or Hydrobacteria as a clade may comprise several candidates more closely related to Proteobacteria, Spirochaetes, PVC group, and FCB group than to bacteria from the clade Terrabacteria. Some of these phyla were classified as part of the proteobacteria. For example, Cavalier-Smith in his proposal of the 6 kingdoms included Acidobacteriota, Aquificota, Chrysiogenota, and Deferribacterota as part of the proteobacteria. Phylogenetic analyzes have found roughly the following phylogeny between the major and some more closely related phyla. According to the phylogenetic analysis of Hug (2016), the relationships could be the following. According to the phylogenetic analysis of Zhu (2019), the relationships could be the following: The following graph shows Cavalier-Smith's version of the tree of life, indicating the status of Gracilicutes. However, this tree is not supported by any molecular analysis so it should not be considered phylogenetic. References Bacteria Bacteriology Infrakingdoms