Microcystis
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Microcystis | |
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Microcystis aeruginosa | |
Scientific classification ![]() | |
Domain: | Bacteria |
Phylum: | Cyanobacteria |
Class: | Cyanophyceae |
Order: | Chroococcales |
Family: | Microcystaceae |
Genus: | Microcystis Kützing, 1833 |
Species | |
Many (see below) |
Microcystis is a genus of freshwater cyanobacteria which includes the harmful algal bloom Microcystis aeruginosa. The cyanobacteria can produce neurotoxins and hepatotoxins, such as microcystin and cyanopeptolin.
Etymology
The genus Microcystis derives from the Greek[1] mikros ("small") + kystis ("bladder")
Physical characteristics
![](http://upload.wikimedia.org/wikipedia/commons/thumb/1/1c/Microcystis_3.jpg/220px-Microcystis_3.jpg)
As the etymological derivation implies, Microcystis is characterized by small cells (a few micrometers in diameter), possessing gas filled vesicles (also lacking individual sheaths).[1] The cells are usually organized into colonies (macroscopic aggregations of which are visible with the naked eye) that begin in a spherical shape, losing coherence to become perforated or irregularly shaped over time. These colonies are bound by a thick mucilage composed of complex polysaccharide compounds, including xylose, mannose, glucose, fucose, galactose, rhamnose, among other compounds.[2]
The coloration of the protoplast is a light blue-green, appearing dark or brown due to optical effects of gas-filled vesicles.[citation needed]
Ecology
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/27/Microcystis_wesenbergii_colony_under_epifluorescence_microscopy.jpg/220px-Microcystis_wesenbergii_colony_under_epifluorescence_microscopy.jpg)
Microcystis is capable of producing large surface blooms through a combination of rapid division and buoyancy regulation by production of gas-filled vesicles. Their ability to regulate buoyancy is key to their dominance of eutrophic waters, by optimally positioning themselves within the photic zone in a stable water column.[citation needed]
Because they can form large surface blooms, they are capable of out-competing other phytoplankton by essentially monopolizing light in the photic zone.[citation needed]
Microcystis is capable of strong uptake of phosphate and nitrogen; they are believed to strongly influence nitrogen to phosphorus ratios ("N:P ratio").[3]
In South Africa, Hartebeestpoort Dam is highly impacted by Microcystis because of elevated phosphate and nitrate levels flowing from the sewers of Johannesburg, one of the few cities in the world that straddles a continental watershed divide [4] and therefore lies upstream of major dams and rivers.[5]
Health risks
Cyanobacteria can produce neurotoxins and hepatotoxins, such as microcystin and cyanopeptolin.[6][7]
Species
Among Microcystis species are the following:[8]
See also
References
- ^ a b "Cyanobacteria: Microcystis". The Silica Secchi Disk. Connecticut College: The SilicaSecchi Disk. Archived from the original on March 26, 2008. Retrieved 24 June 2011.
- ^ "Mechanisms of the inhibitory effect of the cyanobacterium Microcystis aeruginosa on Daphnia galeata's ingestion rate" (PDF). Journal of Plankton Research. 73 (5): 980–984. 1999. doi:10.1021/np900818c. PMID 20405925.
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ignored (help) - ^ Xie, Liqiang; Xie, Ping; Li, Sixin; Tang, Huijuan; Liu, Hong (2003). "The low TN:TP ratio, a cause or a result of Microcystis blooms?". Water Research. 37 (9): 2073–2080. doi:10.1016/S0043-1354(02)00532-8. PMID 12691892.
- ^ Turton, A.R., Schultz, C., Buckle, H, Kgomongoe, M., Malungani, T. & Drackner, M. 2006. Gold, Scorched Earth and Water: The Hydropolitics of Johannesburg. In Water Resources Development, Vol. 22., No. 2; 313-335.
- ^ Turton, A.R. 2015. Sitting on the Horns of a Dilemma: Water as a Strategic Resource in South Africa. In @Liberty, No 6, Issue 22. Johannesburg: South African Institute of Race Relations. Available online http://irr.org.za/reports-and-publications/atLiberty/files/liberty-2013-sitting-on-the-horns-of-a-dilemma-2013-water-as-a-strategic-resource-in-south-africa Archived 2017-10-04 at the Wayback Machine
- ^ Tooming-Klunderud, Ave (2007). "On the Evolution of Nonribosomal Peptide Synthetase Gene Clusters in Cyanobacteria". University of Oslo.
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(help) - ^ "Multiple Toxin Production in the Cyanobacterium Microcystis: Isolation of the Toxic Protease Inhibitor Cyanopeptolin 1020" (PDF). J. Nat. Prod. 73 (5): 980–984. 2010. doi:10.1021/np900818c. PMID 20405925.
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ignored (help) - ^ "Taxonomy Browser Genus: Microcystis". AlgaeBase. Retrieved 24 June 2011.