Streptomyces
From Wikipedia, the free encyclopedia
| iStreptomyces | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Image:Streptomyces sp 01.png Slide culture of a Streptomyces sp.
| ||||||||||
| Scientific classification | ||||||||||
| ||||||||||
| | ||||||||||
|
S. ambofaciens |
Streptomyces is a genus of Actinobacteria, a group of Gram-positive and generally high GC-content bacteria.<ref name=Brock>Madigan M; Martinko J (editors). (2005). Brock Biology of Microorganisms, 11th ed., Prentice Hall. ISBN 0-13-144329-1.</ref> Streptomycetes are found predominantly in soil and in decaying vegetation, and most produce spores. Streptomycetes are noted for their distinct "earthy" odor which results from production of a volatile metabolite, geosmin.
Streptomycetes are characterised by a complex secondary metabolism.<ref name=Brock/> They produce a large number of antibiotics that are in clinical use; the now rarely used Streptomycin takes its name directly from Streptomyces. Streptomycetes are infrequent human pathogens, though infections such as mycetoma can be caused by S. somaliensis.
The complete genome of one of the strain, S. coelicolor A3(2), was published in 2002.<ref name=Bentley_2002>Bentley SD, et al. (2002). "Complete genome sequence of the model actinomycete Streptomyces coelicolor A3(2).". Nature 417: 141–147.</ref> At that time, it contained the largest number of genes of any bacterium characterised so far. The genome sequence of S. avermitilis was completed in 2003.<ref name=Ikeda_2003>Ikeda H; Ishikawa J; Hanamoto A; Shinose M; Kikuchi H; Shiba T; Sakaki Y; Hattori M; Omura S (2003). "Complete genome sequence and comparative analysis of the industrial microorganism Streptomyces avermitilis.". Nat. Biotechnol. 21: 526–531.</ref> This is the first complete genome sequence of the industrial microorganism. Both of these genomes comprise a single chromosome that is linear, unlike most bacterial genomes which comprise a circular chromosome. The genome sequence of Streptomyces scabies, a member of the genus with the ability to cause potato scab disease, has been determined at the Wellcome Trust Sanger Institute and is currently in annotation towards publication in 2007.
S. coelicolor A3(2) taxonomically belongs to S. violaceoruber. Don't mistake S. coelicolor A3(2) for S. coelicolor (Müller) (ATCC 23899).
Contents |
[edit] Streptomyces in Biotechnology
In recent years, researchers have begun to use Streptomyces spp. for production of recombinant human proteins. Traditionally, Escherichia coli (E. coli) was the species of choice to host eukaryotic genes since it was well understood and easy to work with<ref>Brawner M, Poste G, Rosenberg M, Westpheling J. Streptomyces: a host for heterologous gene expression. Curr Opin Biotechnol. 1991 Oct;2(5):674-81. PMID 1367716.</ref><ref>Payne GF, DelaCruz N, Coppella SJ. Improved production of heterologous protein from Streptomyces lividans. Appl Microbiol Biotechnol. 1990 Jul;33(4):395-400. PMID 1369282.</ref>. However, E. coli introduces problems such as incorrect (or lack of) glycosylation and incorrect protein folding, resulting in insolubility and loss of bioactivity of the product<ref>Binnie C, Cossar JD, Stewart DI. Heterologous biopharmaceutical protein expression in Streptomyces. Trends Biotechnol. 1997 Aug;15(8):315-20. PMID 9263479.</ref>. Streptomyces spp. on the other hand have the ability to secrete correctly folded recombinant proteins into the medium after production simplifying the subsequent purification steps. These properties among others make Streptomyces spp. an attractive alternative to other bacteria such as E. coli and Bacillus subtilis.
[edit] References
<references />
