The Aquificota phylum is a diverse collection of bacteria that live in harsh environmental settings. The name Aquificota was given to this phylum based on an early genus identified within this group, Aquifex, which is able to produce water by oxidizing hydrogen. They have been found in springs, pools, and oceans. They are autotrophs, and are the primary carbon fixers in their environments. These bacteria are Gram-negative, non-spore-forming rods. They are true bacteria as opposed to the other inhabitants of extreme environments, the Archaea.
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 Planctomycetota are a phylum of widely distributed bacteria, occurring in both aquatic and terrestrial habitats. They play a considerable role in global carbon and nitrogen cycles, with many species of this phylum capable of anaerobic ammonium oxidation, also known as anammox. Many Planctomycetota occur in relatively high abundance as biofilms, often associating with other organisms such as macroalgae and marine sponges.
Frankia is a genus of nitrogen-fixing bacteria that live in symbiosis with actinorhizal plants, similar to the Rhizobium bacteria found in the root nodules of legumes in the family Fabaceae. Frankia also initiate the forming of root nodules.
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. It's the sole phylum in the kingdom Thermotogati.
Erysipelothrix is a genus of bacteria containing four described species: Erysipelothrix rhusiopathiae, Erysipelothrix tonsillarum, Erysipelothrix inopinata and Erysipelothrix larvae. Additional species have been proposed based on DNA-DNA hybridization studies. "The hallmark of Erysipelothrix is the presence of a type B cell wall, in which the peptide bridge is formed between amino acids at positions 2 and 4 of adjacent peptide side-chains and not, as in the vast majority of bacteria, between amino acids at positions 3 and 4."
The PVC superphylum is a superphylum of bacteria named after its three important members, Planctomycetota, Verrucomicrobiota, and Chlamydiota. Cavalier-Smith postulated that the PVC bacteria probably lost or reduced their peptidoglycan cell wall twice. It has been hypothesised that a member of the PVC clade might have been the host cell in the endosymbiotic event that gave rise to the first proto-eukaryotic cell.
Methanobacteriales is an order of archaeans in the class Methanobacteria. Species within this order differ from other methanogens in that they can use fewer catabolic substrates and have distinct morphological characteristics, lipid compositions, and RNA sequences. Their cell walls are composed of pseudomurein. Most species are Gram-positive with rod-shaped bodies and some can form long filaments. Most of them use formate to reduce carbon dioxide, but those of the genus Methanosphaera use hydrogen to reduce methanol to methane.
In taxonomy, the Methanocaldococcaceae are a family of microbes within the order Methanococcales. It contains two genera, the type genus Methanocaldococcus and Methanotorris. These species are coccoid in form, neutrophilic to slightly acidophilic, and predominantly motile, and they have a very short generation period, from 25 to 45 minutes under optimal conditions. They produce energy exclusively through the reduction of carbon dioxide with hydrogen. Some species have been found in marine hydrothermal vents.
The Synergistota is a phylum of anaerobic bacteria that show Gram-negative staining and have rod/vibrioid cell shape. Although Synergistota have a diderm cell envelope, the genes for various proteins involved in lipopolysaccharides biosynthesis have not yet been detected in Synergistota, indicating that they may have an atypical outer cell envelope. The Synergistota inhabit a majority of anaerobic environments including animal gastrointestinal tracts, soil, oil wells, and wastewater treatment plants and they are also present in sites of human diseases such as cysts, abscesses, and areas of periodontal disease. Due to their presence at illness related sites, the Synergistota are suggested to be opportunistic pathogens but they can also be found in healthy individuals in the microbiome of the umbilicus and in normal vaginal flora. Species within this phylum have also been implicated in periodontal disease, gastrointestinal infections and soft tissue infections. Other species from this phylum have been identified as significant contributors in the degradation of sludge for production of biogas in anaerobic digesters and are potential candidates for use in renewable energy production through their production of hydrogen gas. All of the known Synergistota species and genera are presently part of a single class (Synergistia), order (Synergistiales), and family (Synergistaceae).
Rickettsiella is a genus of the family Coxiellaceae. It should not be confused with Rickettsia. It is currently considered of the Gammaproteobacteria. However, its placement under Coxiellaceae instead of Legionellaceae has been challenged.
The Negativicutes are a class of bacteria in the phylum Bacillota, whose members have a peculiar cell wall with a lipopolysaccharide outer membrane which stains gram-negative, unlike most other members of the Bacillota. Although several neighbouring Clostridia species also stain gram-negative, the proteins responsible for the unusual diderm structure of the Negativicutes may have actually been laterally acquired from Pseudomonadota. Additional research is required to confirm the origin of the diderm cell envelope in the Negativicutes.
Rubripirellula is a genus of bacteria from the family of Planctomycetaceae with five known species. Rubripirellula obstinata has been isolated from the alga Laminaria from the northern coast from Porto in Portugal.
Rubinisphaera is a genus of bacteria from the family of Planctomycetaceae with two known species. Rubinisphaera brasiliensis has been isolated from water from the Lagoa Vermelha from Brazil.
Bythopirellula is a genus of bacteria from the family of Planctomycetaceae with two known species. Bythopirellula goksoyri has been isolated from deep sea iron hydroxide deposits from the Arctic Mid-Ocean Ridge.
Mariniflexile is a genus in the phylum Bacteroidota (Bacteria). The various species have been recovered from sea water, sea urchins, springs, brackish water, and an oyster.
Haloarculaceae is a family of halophilic and mostly chemoorganotrophic archaea within the order Halobacteriales. The type genus of this family is Haloarcula. Its biochemical characteristics are the same as the order Halobacteriales.
Lacipirellulaceae is a family of bacteria.
"Candidatus Brocadia" is a candidatus genus of bacteria, meaning that while it is well-characterized, it has not been grown as a pure culture yet. Due to this, much of what is known about Candidatus species has been discovered using culture-independent techniques such as metagenomic sequence analysis.
Neptunitalea is a genus of bacteria from the family of Flavobacteriaceae with one known species.
