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Microcystis aeruginosa

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Microcystis aeruginosa is a species of freshwater cyanobacteria that can form harmful algal blooms of economic and ecological importance. They are the most common toxic cyanobacterial bloom in eutrophic fresh water. Cyanobacteria produce neurotoxins and peptide hepatotoxins, such as microcystin and cyanopeptolin.[1] Microcystis aeruginosa produces numerous congeners of microcystin, with microcystin-LR being the most common.[2] Microcystis blooms have been reported in at least 108 countries, with the production of microcystin noted in at least 79.[3]

Microcystis aeruginosa
Scientific classification Edit this classification
Domain: Bacteria
Phylum: Cyanobacteria
Class: Cyanophyceae
Order: Chroococcales
Family: Microcystaceae
Genus: Microcystis
Species:
M. aeruginosa
Binomial name
Microcystis aeruginosa
Kützing, 1846

Characteristics

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NOAA MERIS image of large cyanobacterial bloom confirmed as M. aeruginosa[4]
 
Microcystis aeruginosa bloom in Lake Albert in Wagga Wagga, Australia

As the etymological derivation implies, Microcystis is characterized by small cells (of only a few micrometers diameter), which lack individual sheaths.[5]

Cells usually are organized into colonies (large colonies of which may be viewed with the naked eye) that begin in a spherical shape, but lose their coherence to become perforated or irregularly shaped over time in culture. Recent evidence suggests one of the drivers of colony formation is disturbance / water column mixing.[6]

The protoplast is a light blue-green color, appearing dark or brown due to optical effects of gas-filled vesicles; this can be useful as a distinguishing characteristic when using light microscopy. These vesicles provide the buoyancy necessary for M. aeruginosa to stay at a level within the water column at which they can obtain optimum light and carbon dioxide levels for rapid growth.

Ecology

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M. aeruginosa is favored by warm temperatures,[7] but toxicity and maximal growth rates are not totally coupled,[8] as the cyanobacterium has highest laboratory growth rates at 32 °C, while toxicity is highest at 20 °C, lowering in toxicity as a function of increasing temperatures in excess of 28 °C. Growth has been found to be limited below 15 °C.

The aquatic plant Myriophyllum spicatum produces ellagic, gallic, and pyrogallic acids and (+)-catechin, allelopathic polyphenols inhibiting the growth of M. aeruginosa.[9]

Toxins

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See also: Cyanotoxin

M. aeruginosa can produce both neurotoxins (lipopolysaccharides-LPSs)[10] and hepatotoxins (microcystins).

Economic importance

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Because of M. aeruginosa´s microcystin toxin production under the right environmental conditions, it can be a source of drinking water pollution.[11] Water quality mitigation measures in the form of water filtration facilities can lead to increased economic costs, as well as damage to local tourism caused by lake or other waterway closures.[12] In recent years major incidents have occurred in both China[13] and the United States / Canada[14][15][16]

M. aeruginosa is the subject of research into the natural production of butylated hydroxytoluene (BHT),[17] an antioxidant, food additive, and industrial chemical.

Bio-active peptides called aerucyclamides can be isolated from M. aeruginosa.[18][19]

Ecological importance

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In 2009, unprecedented mammal mortality in the southern part of the Kruger National Park led to an investigation which implicated M. aeruginosa. The dead animals included grazers and browsers, which preferred drinking from the leeward side of two dams, a natural point of accumulation for drifting Microcystis blooms. Mammals such as elephants and buffalo that usually wade into water before drinking, were unaffected, as were the resident crocodiles. The source of nutrients that supported the Microcystis growth was narrowed down to the dung and urine voided in the water by a large resident hippo population, unaffected by the bloom. The immediate problem was solved by breaching of the dam walls and draining of the water. M. aeruginosa is the most abundant cyanobacterial genus in South Africa, with both toxic and harmless strains.[20] Some South African water bodies are now highly contaminated, mostly from return flows out of dysfunctional wastewater treatment works that discharge over 4 billion litres (1.1 billion US gallons) of untreated, or at best partially treated sewage into receiving rivers every day, with Hartebeestpoort Dam being among the worst.[21]

Microcystin has been linked to the death of sea otters in 2010, a threatened species in the US.[22] The poisoning probably resulted from eating contaminated bivalves often consumed by sea otters and humans. Such bivalves in the area exhibited significant biomagnification (to 107 times ambient water levels) of microcystin.[23]

Glyphosate metabolism

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Algal blooms of cyanobacteria thrive in the large phosphorus content of agricultural runoff. Besides consuming phosphorus, M. aeruginosa thrives on glyphosate, although high concentrations may inhibit it.[24] M. aeruginosa has shown glyphosate resistance as result of preselective mutations, and glyphosate presence serves as an advantage to this and other microbes that are able to tolerate its effects, while killing those less tolerant.[25] In contrast research in Lake Erie has suggested that glyphosate may lead to blooms of another cyanobacterium - Planktothrix - in place of Microcystis.[26]

References

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  1. ^ Tooming-Klunderud, Ave (2007). On the Evolution of Nonribosomal Peptide Synthetase Gene Clusters in Cyanobacteria (PhD thesis). University of Oslo.
  2. ^ Harke, Matthew J.; Steffen, Morgan M.; Gobler, Christopher J.; Otten, Timothy G.; Wilhelm, Steven W.; Wood, Susanna A.; Paerl, Hans W. (2016). "A review of the global ecology, genomics, and biogeography of the toxic cyanobacterium, Microcystis spp". Harmful Algae. 54: 4–20. doi:10.1016/j.hal.2015.12.007. PMID 28073480.
  3. ^ Harke, Matthew J.; Steffen, Morgan M.; Gobler, Christopher J.; Otten, Timothy G.; Wilhelm, Steven W.; Wood, Susanna A.; Paerl, Hans W. (2016). "A review of the global ecology, genomics, and biogeography of the toxic cyanobacterium, Microcystis spp". Harmful Algae. 54: 4–20. doi:10.1016/j.hal.2015.12.007. PMID 28073480.
  4. ^ "Ecosystem Research and Harmful Algal Blooms". Center of Excellence for Great Lakes and Human Health. NOAA. Archived from the original on 27 September 2011. Retrieved 27 June 2011.
  5. ^ "Cyanobacteria: Microcystis". The Silica Secchi Disk. Connecticut College: The SilicaSecchi Disk. Archived from the original on 26 March 2008. Retrieved 24 June 2011.
  6. ^ Chunni, Zhong; Guijun, Yang; Boqiang, Qin; Wilhelm, Steven W.; Yu, Liu; Lihua, Han; Zheng, Rui; Hongwei, Yang; Zhou, Zhang (2019). "Effects of mixing intensity on colony size and growth of Microcystis aeruginosa". Annales de Limnologie - International Journal of Limnology. 55: 12. doi:10.1051/limn/2019011. ISSN 0003-4088.
  7. ^ Paerl, H. W.; Huisman, J. (2008-04-04). "Blooms Like It Hot". Science. 320 (5872): 57–58. doi:10.1126/science.1155398. ISSN 0036-8075. PMID 18388279. S2CID 142881074.
  8. ^ Peng, Guotao; Martin, Robbie M.; Dearth, Stephen P.; Sun, Xiaocun; Boyer, Gregory L.; Campagna, Shawn R.; Lin, Sijie; Wilhelm, Steven W. (2018-04-03). "Seasonally Relevant Cool Temperatures Interact with N Chemistry to Increase Microcystins Produced in Lab Cultures of Microcystis aeruginosa NIES-843". Environmental Science & Technology. 52 (7): 4127–4136. Bibcode:2018EnST...52.4127P. doi:10.1021/acs.est.7b06532. ISSN 0013-936X. PMID 29522323.
  9. ^ Myriophyllum spicatum-released allelopathic polyphenols inhibiting growth of blue-greenalgaeMicrocystis aeruginosa. Satoshi Nakai, Yutaka Inoue, Masaaki Hosomi and Akihiko Murakami, Water Research, Volume 34, Issue 11, 1 August 2000, Pages 3026–3032, doi:10.1016/S0043-1354(00)00039-7
  10. ^ Mayer, Alejandro M. S.; Jonathan A. Clifford (May 2011). "Cyanobacterial Microcystis aeruginosa Lipopolysaccharide Elicits Release of Superoxide Anion, Thromboxane B2, Cytokines, Chemokines, and Matrix Metalloproteinase-9 by Rat Microglia". Toxicological Sciences. 121 (1): 63–72. doi:10.1093/toxsci/kfr045. PMID 21362633. Archived from the original on 2013-04-15. Retrieved 25 June 2011.
  11. ^ "Cyanobacterial Toxins: Microcystin-LR in drinking water". Background document for development of WHO Guidelines for Drinking Water Quality. World Health Organization (WHO). Retrieved 24 June 2011.
  12. ^ Somek, Hasim. "A Case Report: Algal Bloom of Microcystis aeruginosa in a Drinking-Water Body, Eğirdir Lake, Turkey" (PDF). Turkish Journal of Fisheries and Aquatic Sciences. Archived from the original (PDF) on 4 October 2011. Retrieved 27 June 2011.
  13. ^ Qin, Boqiang; Xu, Pengzhu; Wu, Qinglong; Luo, Liancong; Zhang, Yunlin (2007). "Environmental issues of Lake Taihu, China". Hydrobiologia. 581 (1): 3–14. doi:10.1007/s10750-006-0521-5. ISSN 0018-8158. S2CID 21108027.
  14. ^ Steffen, Morgan M.; Davis, Timothy W.; McKay, R. Michael L.; Bullerjahn, George S.; Krausfeldt, Lauren E.; Stough, Joshua M.A.; Neitzey, Michelle L.; Gilbert, Naomi E.; Boyer, Gregory L.; Johengen, Thomas H.; Gossiaux, Duane C. (2017). "Ecophysiological Examination of the Lake Erie Microcystis Bloom in 2014: Linkages between Biology and the Water Supply Shutdown of Toledo, OH". Environmental Science & Technology. 51 (12): 6745–6755. Bibcode:2017EnST...51.6745S. doi:10.1021/acs.est.7b00856. ISSN 0013-936X. PMID 28535339.
  15. ^ Kramer, Benjamin J.; Davis, Timothy W.; Meyer, Kevin A.; Rosen, Barry H.; Goleski, Jennifer A.; Dick, Gregory J.; Oh, Genesok; Gobler, Christopher J. (2018). Miller, Todd (ed.). "Nitrogen limitation, toxin synthesis potential, and toxicity of cyanobacterial populations in Lake Okeechobee and the St. Lucie River Estuary, Florida, during the 2016 state of emergency event". PLOS ONE. 13 (5): e0196278. Bibcode:2018PLoSO..1396278K. doi:10.1371/journal.pone.0196278. ISSN 1932-6203. PMC 5965861. PMID 29791446.
  16. ^ Steffen, Morgan M.; Zhu, Zhi; McKay, Robert Michael L.; Wilhelm, Steven W.; Bullerjahn, George S. (2014). "Taxonomic assessment of a toxic cyanobacteria shift in hypereutrophic Grand Lake St. Marys (Ohio, USA)". Harmful Algae. 33: 12–18. doi:10.1016/j.hal.2013.12.008.
  17. ^ Babu B, Wu JT (December 2008). "Production of Natural Butylated Hydroxytoluene as an Antioxidant by Freshwater Phytoplankton" (PDF). Journal of Phycology. 44 (6): 1447–1454. doi:10.1111/j.1529-8817.2008.00596.x. PMID 27039859. S2CID 26084768.
  18. ^ Portmann C, Blom JF, Gademann K, Jüttner F (July 2008). "Aerucyclamides A and B: isolation and synthesis of toxic ribosomal heterocyclic peptides from the cyanobacterium Microcystis aeruginosa PCC 7806". Journal of Natural Products. 71 (7): 1193–6. doi:10.1021/np800118g. PMID 18558743.
  19. ^ Portmann C, Blom JF, Kaiser M, Brun R, Jüttner F, Gademann K (November 2008). "Isolation of aerucyclamides C and D and structure revision of microcyclamide 7806A: heterocyclic ribosomal peptides from Microcystis aeruginosa PCC 7806 and their antiparasite evaluation". Journal of Natural Products. 71 (11): 1891–6. doi:10.1021/np800409z. PMID 18973386.
  20. ^ Paul J. Oberholster, Jan G. Myburgh, Danny Govender, Roy Bengis, Anna-Maria Botha Identification of toxigenic Microcystis strains after incidents of wild animal mortalities in the Kruger National Park, South Africa. Ecotoxicology and Environmental Safety (2009), Elsevier doi:10.1016/j.ecoenv.2008.12.014
  21. ^ 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
  22. ^ Stephens, Tim (September 10, 2010). "Sea otter deaths linked to toxin from freshwater bacteria". UC Santa Cruz Newscenter.
  23. ^ Miller, Melissa (2010-09-10). "Evidence for a Novel Marine Harmful Algal Bloom: Cyanotoxin (Microcystin) Transfer from Land to Sea Otters". PLOS ONE. 5 (9): e12576. Bibcode:2010PLoSO...512576M. doi:10.1371/journal.pone.0012576. PMC 2936937. PMID 20844747.
  24. ^ Qiu, Huimin (2013-03-15). "Physiological and biochemical responses of Microcystis aeruginosa to glyphosate and its Roundup® formulation". Journal of Hazardous Materials. 248–249: 172–176. doi:10.1016/j.jhazmat.2012.12.033. PMID 23357506.
  25. ^ López-Rodas, Victoria; Flores-Moya, Antonio; Maneiro, Emilia; Perdigones, Nieves; Marva, Fernando; García, Marta E.; Costas, Eduardo (2007-07-01). "Resistance to glyphosate in the cyanobacterium Microcystis aeruginosa as result of pre-selective mutations". Evolutionary Ecology. 21 (4): 535–547. doi:10.1007/s10682-006-9134-8. S2CID 21762370.
  26. ^ Saxton, Matthew A.; Morrow, Elizabeth A.; Bourbonniere, Richard A.; Wilhelm, Steven W. (2011). "Glyphosate influence on phytoplankton community structure in Lake Erie". Journal of Great Lakes Research. 37 (4): 683–690. Bibcode:2011JGLR...37..683S. doi:10.1016/j.jglr.2011.07.004.
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