出典(authority):フリー百科事典『ウィキペディア(Wikipedia)』「2015/06/28 22:05:25」(JST)
ストレプトマイセス属 | ||||||||||||||||||
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寒天培地上で増殖するStreptomyces sp.
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分類 | ||||||||||||||||||
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学名 | ||||||||||||||||||
Streptomyces Waksman & Henrici 1943 |
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種 | ||||||||||||||||||
S. abietis
S. acidiscabies
S. alboverticillatus
S. aldersoniae
S. caelestis
S. cellostaticus
S. chumphonensis
S. cinereospinus
S. diastatochromogenes
S. globosus
S. guanduensis
S. hypolithicus
S. lavenduligriseus
S. lienomycini
S. rishiriensis
S. salmonis
S. thermovulgaris |
ストレプトマイセス属(-ぞく、Streptomyces、ストレプトミケス属とも)はグラム陽性細菌に分類される真正細菌の一属。現在、668種 (分類学)と38亜種が知られている[1]。
抗生物質の大部分を生産する細菌で、放線菌の多数を占める。主に土壌中に棲息し、中には根菜類に病気を引き起こすものもある。
ゲノムサイズは900万bpで、細菌の中ではかなり大きい。真核生物の出芽酵母(1200万bp)とそれ程変わらない大きさである。
この節の加筆が望まれています。 |
この節の加筆が望まれています。 |
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この項目は、真正細菌(バクテリア)に関連した書きかけの項目です。この項目を加筆・訂正などしてくださる協力者を求めています(Portal:生き物と自然/ウィキプロジェクト 生物)。 |
Streptomyces | |
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Slide culture of a Streptomyces species | |
Scientific classification | |
Kingdom: | Bacteria |
Phylum: | Actinobacteria |
Class: | Actinobacteria |
Order: | Actinomycetales |
Family: | Streptomycetaceae |
Genus: | Streptomyces Waksman & Henrici 1943 |
Diversity | |
About 550 species | |
Synonyms | |
Streptoverticillium |
Streptomyces is the largest genus of Actinobacteria and the type genus of the family Streptomycetaceae.[1] Over 500 species of Streptomyces bacteria have been described.[2] As with the other Actinobacteria, streptomycetes are Gram-positive, and have genomes with high GC content.[3] Found predominantly in soil and decaying vegetation, most streptomycetes produce spores, and are noted for their distinct "earthy" odor that results from production of a volatile metabolite, geosmin.
Streptomycetes are characterised by a complex secondary metabolism.[3] They produce over two-thirds of the clinically useful antibiotics of natural origin (e.g., neomycin, cypemycin, grisemycin, bottromycins and chloramphenicol).[4][5] The now uncommonly used streptomycin takes its name directly from Streptomyces. Streptomycetes are infrequent pathogens, though infections in humans, such as mycetoma, can be caused by S. somaliensis and S. sudanensis, and in plants can be caused by S. caviscabies, S. acidiscabies, S. turgidiscabies and S. scabies.
Streptomyces is the type genus of the family Streptomycetaceae[6] and currently covers close to 576 species with the number increasing every year.[7] Acidophilic and acid-tolerant strains that were initially classified under this genus have later been moved to Kitasatospora (1997) [8] and Streptacidiphilus (2003).[9] Species nomenclature are usually based on their color of hyphae and spores.
Saccharopolyspora erythraea was formerly placed in the present genus, too (as Streptomyces erythraeus).
The genus Streptomyces includes aerobic, Gram-positive, filamentous bacteria that produce well-developed vegetative hyphae (between 0.5-2.0 µm in diameter) with branches. They form a complex substrate mycelium that aids in scavenging organic compounds from their substrates.[10] Although the mycelia and the aerial hyphae that arise from them are amotile, mobility is achieved by dispersion of spores.[10] Spore surfaces may be hairy, rugose, smooth, spiny or warty.[11] In some species, aerial hyphae consist of long, straight filaments, which bear 50 or more spores at more or less regular intervals, arranged in whorls (verticils). Each branch of a verticil produces, at its apex, an umbel, which carries from two to several chains of spherical to ellipsoidal, smooth or rugose spores.[10] Some strains form short chains of spores on substrate hyphae. Sclerotia-, pycnidia-, sporangia-, and synnemata-like structures are produced by some strains.
The complete genome of "S. coelicolor strain A3(2)" was published in 2002.[12] At the time, the "S. coelicolor" genome was thought to contain the largest number of genes of any bacterium.[12] The chromosome is 8,667,507 bp long with a GC-content of 72.1%, and is predicted to contain 7,825 protein-encoding genes.[12] In terms of taxonomy, "S. coelicolor A3(2)" belongs to the species S. violaceoruber, and is not a validly described separate species; "S. coelicolor A3(2)" is not to be mistaken for the actual S. coelicolor (Müller), although it is often referred to as S. coelicolor for convenience.[13]
The first complete genome sequence of S. avermitilis was completed in 2003.[14] Each of these genomes forms a chromosome with a linear structure, unlike most bacterial genomes, which exist in the form of circular chromosomes.[15] The genome sequence of S. scabies, a member of the genus with the ability to cause potato scab disease, has been determined at the Wellcome Trust Sanger Institute. At 10.1 Mbp long and encoding 9,107 provisional genes, it is the largest known Streptomyces genome sequenced, probably due to the large pathogenicity island.[15][16]
In recent years, biotechnology researchers have begun using Streptomyces species for heterologous expression of proteins. Traditionally, Escherichia coli was the species of choice to express eukaryotic genes, since it was well understood and easy to work with.[17][18] Expression of eukaryotic proteins in E. coli may be problematic. Sometimes, proteins do not fold properly, which may lead to insolubility, deposition in inclusion bodies, and loss of bioactivity of the product.[19] Though E. coli strains have secretion mechanisms, these are of low efficiency and result in secretion into the periplasmic space, whereas secretion by a Gram-positive bacterium such as a Streptomyces species results in secretion directly into the extracellular medium. In addition, Streptomyces species have more efficient secretion mechanisms than E.coli. The properties of the secretion system is an advantage for industrial production of heterologously expressed protein because it simplifies subsequent purification steps and may increase yield. These properties among others make Streptomyces spp. an attractive alternative to other bacteria such as E. coli and Bacillus subtilis.[19]
So far, ten species belonging to this genus have been found to be pathogenic to plants:[7]
Streptomyces is the largest antibiotic-producing genus, producing antibacterial, antifungal, and antiparasitic drugs, and also a wide range of other bioactive compounds, such as immunosuppressants.[20] Almost all of the bioactive compounds produced by Streptomyces are initiated during the time coinciding with the aerial hyphal formation from the substrate mycelium.[10]
Streptomycetes produce numerous antifungal compounds of medicinal importance, including nystatin (from S. noursei), amphotericin B (from S. nodosus), and natamycin (from S. natalensis).
Members of the Streptomyces genus are the source for numerous antibacterial pharmaceutical agents; among the most important of these are:
Clavulanic acid (from S. clavuligerus) is a drug used in combination with some antibiotics (like amoxicillin) to block and/or weaken some bacterial-resistance mechanisms by irreversible beta-lactamase inhibition. Novel antiinfectives currently being developed include Guadinomine (from Streptomyces sp. K01-0509),[29] a compound that blocks the Type III secretion system of Gram-negative bacteria.
S. avermitilis is responsible for the production of one of the most widely employed drugs against nematode and arthropod infestations, ivermectin.
Less commonly, streptomycetes produce compounds used in other medical treatments: migrastatin (from S. platensis) and bleomycin (from S. verticillus) are antineoplastic (anticancer) drugs.
S. hygroscopicus and S. viridochromogenes produce the natural herbicide bialaphos.
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リンク元 | 「ストレプトマイセス属」「ストレプトミセス」「Streptomycetaceae」 |
拡張検索 | 「Streptomyces coelicolor」「Streptomyces antibioticus」「Streptomyces lividans」「Streptomyces kanamyceticus」 |
関連記事 | 「streptomyces」 |
ストレプトマイセス属 : 約 82,100 件 ストレプトミセス属 : 99 件 ストレプトマイセス : 約 20,000 件 ストレプトミセス : 約 19,600 件
ストレプトマイセス・セリカラー、ストレプトミセス・セリカラー
ストレプトマイセス・アンチビオチクス、ストレプトミセス・アンチビオチクス
ストレプトマイセス・リビダンス、ストレプトミセス・リビダンス
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