Bacterial phyla

The following is a list of bacterial phyla that have been validly published as of December 2023. The following is a list of candidate phyla that have not been cultured. ==Supergroups==

Despite the unclear branching order for most bacterial phyla, several groups of phyla consistently cluster together and are referred to as supergroups or superphyla. In some instances, bacterial clades clearly consistently cluster together but it is unclear what to call the group. For example, the Candidate Phyla Radiation includes the Patescibacteria group which includes Microgenomates group which includes over 11 bacterial phyla. The LPSN recognizes four kingdoms of bacteria as validly published: Bacillati, Fusobacteriati, Pseudomonadati and Thermotogati. Candidate phyla radiation (CPR) The CPR is a descriptive term referring to a massive monophyletic radiation of candidate phyla that exists within the Bacterial domain. It includes two main clades, the Microgenomates and Parcubacteria groups, each containing the eponymous superphyla and a few other phyla. Patescibacteria The superphylum Patescibacteria was originally proposed to encompass the phyla Microgenomates (OP11), Parcubacteria (OD1), and Gracilibacteria (GNO2 / BD1-5). Sphingobacteria The Sphingobacteria (FCB group) includes Bacteroidota, Calditrichota, Chlorobiota, candidate phylum "Cloacimonetes", Fibrobacterota, Gemmatimonadota, Ignavibacteriota, candidate phylum "Latescibacteria", candidate phylum "Marinimicrobia", and candidate phylum "Zixibacteria". Microgenomates Microgenomates was originally thought to be a single phylum although evidence suggests it actually encompasses over 11 bacterial phyla, For example, the Deltaproteobacteria group does not consistently form a monophyletic lineage with the other Proteobacteria classes. Planctobacteria The Planctobacteria (PVC group) includes Chlamydiota, Lentisphaerota, candidate phylum "Omnitrophica", Planctomycetota, candidate phylum "Poribacteria", and Verrucomicrobiota. Bacillati The kingdom Bacillati, includes Actinomycetota, "Cyanobacteria/Melainabacteria clade", Deinococcota, Chloroflexota, Bacillota, and candidate phylum OP10. Cryptic superphyla Several candidate phyla (Microgenomates, Omnitrophica, Parcubacteria, and Saccharibacteria) and several accepted phyla (Elusimicrobiota, Caldisericota, and Armatimonadota) have been suggested to actually be superphyla that were incorrectly described as phyla because rules for defining a bacterial phylum are lacking or due to a lack of sequence diversity in databases when the phylum was first established. For example, it is suggested that candidate phylum Parcubacteria is actually a superphylum that encompasses 28 subordinate phyla and that phylum Elusimicrobia is actually a superphylum that encompasses 7 subordinate phyla. == Historical perspective ==

'' of which 16S makes up a part. Proteins are shown in blue and the single RNA strand in tan. Given the rich history of the field of bacterial taxonomy and the rapidity of changes therein in modern times, it is often useful to have a historical perspective on how the field has progressed in order to understand references to antiquated definitions or concepts. When bacterial nomenclature was controlled under the Botanical Code, the term division was used, but now that bacterial nomenclature (with the exception of cyanobacteria) is controlled under the Bacteriological Code, the term phylum is preferred. In 1987, Carl Woese, regarded as the forerunner of the molecular phylogeny revolution, divided Eubacteria into 11 divisions based on 16S ribosomal RNA (SSU) sequences, listed below. • Purple Bacteria and their relatives (later renamed Proteobacteria) • alpha subdivision (purple non-sulfur bacteria, rhizobacteria, Agrobacterium, Rickettsiae, Nitrobacter) • beta subdivision (Rhodocyclus, (some) Thiobacillus, Alcaligenes, Spirillum, Nitrosovibrio) • gamma subdivision (enterics, fluorescent pseudomonads, purple sulfur bacteria, Legionella, (some) Beggiatoa) • delta subdivision (Sulfur and sulfate reducers (Desulfovibrio), Myxobacteria, Bdellovibrio) • Gram-positive Eubacteria • High-G+C species (later renamed Actinobacteria) (Actinomyces, Streptomyces, Arthrobacter, Micrococcus, Bifidobacterium) • Low-G+C species (later renamed Firmicutes or Thermi) • Deinococcus group (Deinococcus radiodurans) • Thermophiles (Thermus aquaticus) • Green non-sulfur bacteria and relatives (later renamed Chloroflexi) • Chloroflexus group (Chloroflexus, Herpetosiphon) • Thermomicrobium group (Thermomicrobium roseum) • Thermotogae (Thermotoga maritima) Traditionally, phylogeny was inferred and taxonomy established based on studies of morphology. The advent of molecular phylogenetics has allowed for improved elucidation of the evolutionary relationship of species by analyzing their DNA and protein sequences, for example their ribosomal DNA. The lack of easily accessible morphological features, such as those present in animals and plants, hampered early efforts of classification and resulted in erroneous, distorted and confused classification, an example of which, noted Carl Woese, is Pseudomonas whose etymology ironically matched its taxonomy, namely "false unit". Many bacterial taxa were re-classified or re-defined using molecular phylogenetics. The advent of molecular sequencing technologies has allowed for the recovery of genomes directly from environmental samples (i.e. bypassing culturing), leading to rapid expansion of our knowledge of the diversity of bacterial phyla. These techniques are genome-resolved metagenomics and single-cell genomics. ==See also==