The Actinomycetota (or Actinobacteria) are a diverse phylum of Gram-positive bacteria with high GC content. They can be terrestrial or aquatic animal. They are of great importance to land flora because of their contributions to soil systems. In soil they help to decomposition the organic matter of dead organisms so the molecules can be taken up anew by . While this role is also played by fungus, Actinomycetota are much smaller and likely do not occupy the same ecological niche. In this role the colonies often grow extensive mycelium, as fungi do, and the name of an important order of the phylum, Actinomycetales (the actinomycetes), reflects that they were long believed to be fungi. Some soil actinomycetota (such as Frankia) live symbiosis with the plants whose pervade the soil, fixing nitrogen for the plants in exchange for access to some of the plant's . Other species, such as many members of the genus Mycobacterium, are important .
Beyond the great interest in Actinomycetota for their soil role, much is yet to be learned about them. Although currently understood primarily as soil bacteria, they might be more abundant in fresh waters. Actinomycetota is one of the dominant bacterial phyla and contains one of the largest of bacterial genera, Streptomyces. Streptomyces and other actinomycetota are major contributors to biological buffer solution of soils. They are also the source of many .
The Actinomycetota genus Bifidobacterium is the most common bacteria in the microbiome of human infants. Although adults have fewer bifidobacteria, intestinal bifidobacteria help maintain the mucosal barrier and reduce lipopolysaccharide in the intestine.
Although some of the largest and most complex bacterial cells belong to the Actinomycetota, the group of marine Actinomarinales has been described as possessing the smallest free-living prokaryotic cells.
Some or Antarctic Actinomycetota are said to be the oldest living organism on Earth, frozen in permafrost at around half a million years ago. The symptoms of life were detected by release from permafrost samples 640 kya or younger.
General
Of those Actinomycetota not in the Actinomycetales, Gardnerella is one of the most researched. Classification of Gardnerella is controversial, and MeSH catalogues it as both a Gram-positive and Gram-negative organism.
Actinomycetota, especially Streptomyces spp., are recognized as the producers of many bioactive metabolites that are useful to humans in medicine, such as antibacterials, antifungals, antivirals, antithrombotics, immunomodifiers, antitumor drugs, and enzyme inhibitors; and in agriculture, including , herbicides, fungicides, and growth-promoting substances for plants and animals. Actinomycetota-derived antibiotics that are important in medicine include aminoglycosides, anthracyclines, chloramphenicol, macrolide, tetracyclines, etc.
Actinomycetota have high guanine and cytosine content in their DNA. The G+C content of Actinomycetota can be as high as 70%, though some may have a low G+C content.
Analysis of glutamine synthetase sequence has been suggested for phylogenetic analysis of the Actinomycetota.
Phylogeny
See also
- List of bacteria genera
- List of bacterial orders
- List of bacterial vaginosis microbiota
Further reading
External links
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