The Chlamydiota are a bacterial phylum and class whose members are remarkably diverse, including pathogens of humans and animals, symbionts of ubiquitous protozoa, and marine sediment forms not yet well understood. All of the Chlamydiota that humans have known about for many decades are obligate intracellular bacteria; in 2020 many additional Chlamydiota were discovered in ocean-floor environments, and it is not yet known whether they all have hosts. Historically it was believed that all Chlamydiota had a peptidoglycan-free cell wall, but studies in the 2010s demonstrated a detectable presence of peptidoglycan, as well as other important proteins.
The Thermotogota are a phylum of the domain Bacteria. The phylum contains a single class, Thermotogae. The phylum Thermotogota is composed of Gram-negative staining, anaerobic, and mostly thermophilic and hyperthermophilic bacteria.
Rubrobacter is a genus of Actinomycetota. It is radiotolerant and may rival Deinococcus radiodurans in this regard.
Fibrobacterota is a small bacterial phylum which includes many of the major rumen bacteria, allowing for the degradation of plant-based cellulose in ruminant animals. Members of this phylum were categorized in other phyla. The genus Fibrobacter was removed from the genus Bacteroides in 1988.
The Gemmatimonadota are a phylum of bacteria established in 2003. The phylum contains two classes Gemmatimonadetes and Longimicrobia.
The Sphingobacteriales is an order of environmental bacteria.
The Chloroflexota are a phylum of bacteria containing isolates with a diversity of phenotypes, including members that are aerobic thermophiles, which use oxygen and grow well in high temperatures; anoxygenic phototrophs, which use light for photosynthesis ; and anaerobic halorespirers, which uses halogenated organics as electron acceptors.
Tannerella forsythia is an anaerobic, Gram-negative bacterial species of the Bacteroidota phylum. It has been implicated in periodontal diseases and is a member of the red complex of periodontal pathogens. T. forsythia was previously named Bacteroides forsythus and Tannerella forsythensis.
Lentisphaerota is a phylum of bacteria closely related to Chlamydiota and Verrucomicrobiota.
Bacterial phyla constitute the major lineages of the domain Bacteria. While the exact definition of a bacterial phylum is debated, a popular definition is that a bacterial phylum is a monophyletic lineage of bacteria whose 16S rRNA genes share a pairwise sequence identity of ~75% or less with those of the members of other bacterial phyla.
Caldisericum exile is a species of bacteria sufficiently distinct from other bacteria to be placed in its own family, order, class and phylum. It is the first member of the thermophilic candidate phylum OP5 to be cultured and described.
Armatimonadota is a phylum of gram-negative bacteria.
The Solirubrobacterales are an order of Actinomycetota.
The Nakamurella is a genus of bacteria.
The Selenomonadales are an order of bacteria within the class Negativicutes; unlike most other members of Bacillota, they are Gram-negative. The phylogeny of this order was initially determined by 16S rRNA comparisons. More recently, molecular markers in the form of conserved signature indels (CSIs) have been found specific for all Selenomonadales species. On the basis of these markers, the Selenomonadales are inclusive of two distinct families, and are no longer the sole order within the Negativicutes. Several CSIs have also been found specific for both families, Sporomusaceae and Selenomonadceae. Samples of bacterial strains within this order have been isolated from the root canals of healthy human teeth.
The Nautiliaceae are a family of bacteria placed in an order to itself, Nautiliales, or in the order Campylobacterales. The members of the family are all thermophilic.
The Natranaerobiales are an order of bacteria placed within the class Clostridia. This order contains the thermophilic bacterial species Natranaerobius thermophilus and the related species Natranaerobaculum magadiense.
Euzebya is a genus of Gram-positive bacteria.
Thermoleophilum is a genus of Actinomycetota.
The Ignavibacteriales are an order of obligately anaerobic, non-photosynthetic bacteria that are closely related to the green sulfur bacteria.
