A spirochaete or spirochete is a member of the phylum Spirochaetota, which contains distinctive diderm (double-membrane) Gram-negative bacteria, most of which have long, helically coiled cells. Spirochaetes are chemoheterotrophic in nature, with lengths between 3 and 500 μm and diameters around 0.09 to at least 3 μm.
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.
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 is the sole phylum in the kingdom Thermotogati.
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.
The Acidobacteriaceae are a family of Acidobacteriota.
Lentisphaerota is a phylum of bacteria closely related to Chlamydiota and Verrucomicrobiota.
The FCB group is a superphylum of bacteria named after the main member phyla Fibrobacterota, Chlorobiota, and Bacteroidota. The members are considered to form a clade due to a number of conserved signature indels.
The phylum Elusimicrobiota, previously known as "Termite Group 1", has been shown to be widespread in different ecosystems like marine environment, sewage sludge, contaminated sites and soils, and toxic wastes. The high abundance of Elusimicrobiota representatives is only seen for the lineage of symbionts found in termites and ants.
Methylacidiphilum infernorum is an extremely acidophilic methanotrophic aerobic bacteria first isolated and described in 2007 growing on soil and sediment on Hell's Gate, New Zealand. Similar organisms have also been isolated from geothermal sites on Italy and Russia.
Singulisphaera is a moderately acidophilic and mesophilic genus of bacteria from the family of Planctomycetaceae.
The Ignavibacteriales are an order of obligately anaerobic, non-photosynthetic bacteria that are closely related to the green sulfur bacteria.
Cerasicoccus is a Gram-negative, non-motile, obligately aerobic and chemoheterotrophic bacterial genus from the family Puniceicoccaceae.
Pelagicoccus is a Gram-negative genus of bacteria from the family of Puniceicoccaceae.
The Opitutales is an order in the phylum Verrucomicrobiota.
The Opitutaceae are a Gram-negative and chemoheterotrophic order of the domain Bacteria. Opitutaceae bacteria were isolated from soil and coastal marine springs.
The "Acidobacteriia" is a class of Acidobacteriota.
Omnitrophica or Omnitrophota is a proposed candidate phylum of bacteria with chemolithoautotrophic nutrition. It was previously known as candidate phylum OP3. These bacteria appear to thrive in anoxic environments, such as deep marine sediments, hypersaline environments, freshwater lakes, aquifers, flooded soils, and methanogenic bioreactors. Genomic analyzes have found genes responsible for the construction of magnetosomes, which are also present in other phyla of bacteria. These organelles have magnetic properties, which causes bacteria to orient themselves magnetically in the environment. Omnitrophica is part of the PVC superphylum along with the phyla Planctomycetota, Verrucomicrobiota and Chlamydiota with which it shares a common ancestor.
