The Actinomycetota are a diverse phylum of Gram-positive bacteria with high GC content. They can be terrestrial or aquatic. They are of great importance to land flora because of their contributions to soil systems. In soil they help to decompose the organic matter of dead organisms so the molecules can be taken up anew by plants. While this role is also played by fungi, Actinomycetota are much smaller and likely do not occupy the same ecological niche. In this role the colonies often grow extensive mycelia, as fungi do, and the name of an important order of the phylum, Actinomycetales, reflects that they were long believed to be fungi. Some soil actinomycetota live symbiotically with the plants whose roots pervade the soil, fixing nitrogen for the plants in exchange for access to some of the plant's saccharides. Other species, such as many members of the genus Mycobacterium, are important pathogens.
Fusobacteriota are obligately anaerobic non-sporeforming Gram-negative bacilli. Since the first reports in the late nineteenth century, various names have been applied to these organisms, sometimes with the same name being applied to different species. More recently, not only have there been changes to the nomenclature, but also attempts to differentiate between species which are believed to be either pathogenic or commensal or both. Because of their asaccharolytic nature, and a general paucity of positive results in routine biochemical tests, laboratory identification of the Fusobacteriota has been difficult. However, the application of novel molecular biological techniques to taxonomy has established a number of new species, together with the subspeciation of Fusobacterium necrophorum and F. nucleatum, and provided new methods for identification. The involvement of Fusobacteriota in a wide spectrum of human infections causing tissue necrosis and septicaemia has long been recognised, and, more recently, their importance in intra-amniotic infections, premature labour and tropical ulcers has been reported.
Micromonosporaceae is a family of bacteria of the class Actinomycetia. They are gram-positive, spore-forming soil organisms that form a true mycelium.
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.
In taxonomy, the Thermoplasmatales are an order of the Thermoplasmata. All are acidophiles, growing optimally at pH below 2. Picrophilus is currently the most acidophilic of all known organisms, being capable of growing at a pH of -0.06. Many of these organisms do not contain a cell wall, although this is not true in the case of Picrophilus. Most members of the Thermotoplasmata are thermophilic.
The Actinomycetia are a class of bacteria.
Streptomycetaceae is a family of the class Actinomycetota, making up the monotypic order Streptomycetales. It includes the important genus Streptomyces. This was the original source of many antibiotics, namely streptomycin, the first antibiotic against tuberculosis.
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.
Acrocarpospora is a genus of bacteria in the phylum Actinomycetota. The major respiratory quinone is menaquinone MK-9(H ) and use madurose, an actinomycete whole-cell sugar.
Actinocatenispora is a genus in the phylum Actinomycetota (Bacteria).
Actinocorallia is a genus in the phylum Actinomycetota (Bacteria).
Actinospica is a genus in the phylum Actinomycetota (Bacteria).
Cryptosporangium is a genus of bacteria in the phylum Actinomycetota.
Desulfosporosinus is a genus of strictly anaerobic, sulfate-reducing bacteria, often found in soil.
Bulleidia is a Gram-positive, non-spore-forming, anaerobic and non-motile genus from the family of Erysipelotrichidae, with one known species.
Sphaerisporangium is a Gram-positive genus of bacteria from the family of Streptosporangiaceae.
Marinactinospora is a genus in the phylum Actinomycetota (Bacteria). It contains a single species, Marinactinospora thermotolerans. The species has a high tolerance for environmental temperatures, up to 55°C.
Tumebacillus is a genus of Gram-positive, rod-shaped, spore-forming bacteria. Members of the genus can be motile or non-motile, and form white or yellow colonies on R2A agar.
Catenulispora is a Gram-positive, rod-shaped and aerobic genus of bacteria.
Euzebya is a genus of Gram-positive bacteria.
