Biology:Actinobacteria
| "Actinobacteria" | |
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| Scanning electron micrograph of Actinomyces israelii. | |
Scientific classification 
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| Domain: | Bacteria |
| Clade: | Terrabacteria |
| Phylum: | Actinomycetota Goodfellow 2012[1] |
| Classes[2] | |
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| Synonyms | |
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The "Actinobacteria" are a phylum of mostly Gram-positive bacteria. They can be terrestrial or aquatic.[3] They are of great economic importance to humans because agriculture and forests depend on 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, Actinobacteria are much smaller and likely do not occupy the same ecological niche. In this role the colonies often grow extensive mycelia, like a fungus would, and the name of an important order of the phylum, Actinomycetales (the actinomycetes), reflects that they were long believed to be fungi. Some soil actinobacteria (such as Frankia) 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.
Beyond the great interest in "Actinobacteria" 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.[4] "Actinobacteria" is one of the dominant bacterial phyla and contains one of the largest of bacterial genera, Streptomyces.[5] Streptomyces and other actinobacteria are major contributors to biological buffering of soils.[6] They are also the source of many antibiotics.
The "Actinobacteria" genus Bifidobacterium is the most common bacterium in the microbiome of human infants.[7] Although adults have fewer bifidobacteria, intestinal bifidobacteria help maintain the mucosal barrier and reduce lipopolysaccharide in the intestine.[8]
Although some of the largest and most complex bacterial cells belong to the "Actinobacteria", the group of marine Actinomarinales has been described as possessing the smallest free-living prokaryotic cells.[9]
Some Siberian or Antarctic "Actinobacteria" is said to be the oldest living organism on Earth, frozen in permafrost at around half a million years ago.[10][11] The symptoms of life were detected by CO
2 release from permafrost samples 640 kya or younger. [12]
General
Most "Actinobacteria" of medical or economic significance are in class Actinobacteria, and belong to the order Actinomycetales. While many of these cause disease in humans, Streptomyces is notable as a source of antibiotics.[citation needed]
Of those "Actinobacteria" 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.[13]
"Actinobacteria", especially Streptomyces spp., are recognized as the producers of many bioactive metabolites that are useful to humans in medicine, such as antibacterials,[14] antifungals,[15] antivirals, antithrombotics, immunomodifiers, antitumor drugs, and enzyme inhibitors; and in agriculture, including insecticides, herbicides, fungicides, and growth-promoting substances for plants and animals.[16][17] "Actinobacteria"-derived antibiotics that are important in medicine include aminoglycosides, anthracyclines, chloramphenicol, macrolide, tetracyclines, etc.
"Actinobacteria" have high guanine and cytosine content in their DNA.[18] The G+C content of "Actinobacteria" can be as high as 70%, though some may have a low G+C content.[19]
Analysis of glutamine synthetase sequence has been suggested for phylogenetic analysis of the "Actinobacteria".[20]
Phylogeny
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN).[2] The phylogeny is based on whole-genome analysis.[21]
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See also
References
- ↑ "Phylum XXVI. Actinobacteria phyl. nov.". Bergey's Manual of Systematic Bacteriology. 5 (2nd ed.). New York, NY: Springer. 2012. pp. 33–34.
- ↑ 2.0 2.1 "Actinobacteria". List of Prokaryotic names with Standing in Nomenclature (LPSN). https://lpsn.dsmz.de/phylum/actinobacteria.
- ↑ "Evidence excluding the root of the tree of life from the actinobacteria". Mol. Biol. Evol. 25 (1): 1–4. January 2008. doi:10.1093/molbev/msm249. PMID 18003601.
- ↑ Lopez-Garcia, Purification, ed (2011). "Metagenomics of the water column in the pristine upper course of the Amazon river". PLOS ONE 6 (8): e23785. doi:10.1371/journal.pone.0023785. PMID 21915244. Bibcode: 2011PLoSO...623785G.
- ↑ C.Michael Hogan.. 2010. Bacteria. Encyclopedia of Earth. eds. Sidney Draggan and C.J.Cleveland, National Council for Science and the Environment, Washington DC
- ↑ Ningthoujam, Debananda S.; Sanasam, Suchitra; Tamreihao, K; Nimaichand, Salam (November 2009). "Antagonistic activities of local actinomycete isolates against rice fungal pathogens". African Journal of Microbiology Research 3 (11): 737–742.
- ↑ "Diversity of bifidobacteria within the infant gut microbiota". PLOS ONE 7 (5): e36957. 2012-05-11. doi:10.1371/journal.pone.0036957. PMID 22606315. Bibcode: 2012PLoSO...736957T.
- ↑ "Microbial translocation in chronic liver diseases". International Journal of Microbiology 2012: 694629. 2012. doi:10.1155/2012/694629. PMID 22848224.
- ↑ "Metagenomics uncovers a new group of low GC and ultra-small marine Actinobacteria". Scientific Reports 3: 2471. 2013. doi:10.1038/srep02471. PMID 23959135. Bibcode: 2013NatSR...3E2471G.
- ↑ Sussman: Oldest Plants, The Guardian , 2 May 2010
- ↑ "It's Okay to be Smart • the oldest living thing in the world: These". https://www.itsokaytobesmart.com/post/91481365622/siberian-actinobacteria-oldest-living-thing.
- ↑ Johnson, S. S.; Hebsgaard, M. B.; Christensen, T. R.; Mastepanov, M.; Nielsen, R.; Munch, K.; Brand, T.; Gilbert, M. T. P. et al. (2007). "Ancient bacteria show evidence of DNA repair". Proceedings of the National Academy of Sciences 104 (36): 14401–14405. doi:10.1073/pnas.0706787104. PMID 17728401. Bibcode: 2007PNAS..10414401J.
- ↑ Gardnerella at the US National Library of Medicine Medical Subject Headings (MeSH)
- ↑ Mahajan, GB (2012). "Antibacterial agents from actinomycetes - a review". Frontiers in Bioscience 4: 240–53. doi:10.2741/e373.
- ↑ Gupte, M.; Kulkarni, P.; Ganguli, B.N. (2002). "Antifungal Antibiotics". Appl. Microbiol. Biotechnol. 58 (1): 46–57. doi:10.1007/s002530100822. PMID 11831475.
- ↑ Bressan, W (2003). "Biological control of maize seed pathogenic fungi by use of actinomycetes". Biocontrol 48 (2): 233–240. doi:10.1023/a:1022673226324.
- ↑ Atta, M.A (2009). "Antimycin-A Antibiotic Biosynthesis Produced by Streptomyces Sp. AZ-AR-262: Taxonomy, Fermentation, Purification and Biological Activities". Austral. J. Basic and Appl. Sci. 3: 126–135.
- ↑ Ventura, M.; Canchaya, C.; Tauch, A.; Chandra, G.; Fitzgerald, G. F.; Chater, K. F.; van Sinderen, D. (5 September 2007). "Genomics of Actinobacteria: Tracing the Evolutionary History of an Ancient Phylum". Microbiology and Molecular Biology Reviews 71 (3): 495–548. doi:10.1128/MMBR.00005-07. PMID 17804669.
- ↑ "Breaking a paradigm:cosmopolitan and abundant freshwater actinobacteria are low GC". Environmental Microbiology Reports 4 (1): 29–35. 2012. doi:10.1111/j.1758-2229.2011.00274.x. PMID 23757226.
- ↑ "Glutamine synthetase sequence evolution in the mycobacteria and their use as molecular markers for "Actinobacteria" speciation". BMC Evol. Biol. 9: 48. 2009. doi:10.1186/1471-2148-9-48. PMID 19245690.
- ↑ "Genome-Based Taxonomic Classification of the Phylum Actinobacteria". Front. Microbiol. 9: 2007. 2018. doi:10.3389/fmicb.2018.02007. PMID 30186281.
Further reading
- Pandey, B.; Ghimire, P.; Agrawal, V.P. (January 12–15, 2004). "Studies on the antibacterial activity of the Actinomycetes isolated from the Khumbu Region of Nepal". International Conference on the Great Himalayas: Climate, Health, Ecology, Management and Conservation. Kathmandu. http://www.aehms.org/pdf/Panday%20F.pdf.
- Baltz, R.H. (2005). "Antibiotic discovery from Actinomycetes: Will a renaissance follow the decline and fall?". SIM News 55: 186–196.
- Baltz, R.H. (2007). "Antimicrobials from Actinomycetes: Back to the Future". Microbe 2 (3): 125–131. http://www.microbemagazine.org/index.php?option=com_content&view=article&id=2221:antimicrobials-from-actinomycetes-back-to-the-future&catid=546&Itemid=731.
External links
Wikidata ☰ Q130914 entry
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