Editing Cyanotoxin (section)

==Background==
[[File:Satellite image of cyanobacteria bloom in the Great Lakes.png|thumb|upright=1.4|right|Satellite image of cyanobacteria bloom in the [[Great Lakes]]]]
{{main|Cyanobacteria}}

[[Cyanobacteria]] are ecologically one of the most prolific groups of [[phototroph]]ic [[prokaryote]]s in both marine and freshwater habitats. Both the beneficial and detrimental aspects of cyanobacteria are of considerable significance. They are important [[primary producer]]s as well as an immense source of several secondary products, including an array of toxic compounds known as cyanotoxins. Abundant growth of cyanobacteria in freshwater, [[estuarine]], and [[coastal ecosystem]]s due to increased anthropogenic [[eutrophication]] and global climate change has created serious concern toward harmful bloom formation and surface water contamination.<ref name=Rastogi2015 />

Cyanobacteria are considered the oldest groups of [[photosynthetic]] prokaryotes{{hsp}}<ref>{{cite journal |doi = 10.3389/fmicb.2014.00359|doi-access = free|title = Physiology and molecular biology of aquatic cyanobacteria|year = 2014|last1 = Bullerjahn|first1 = George S.|last2 = Post|first2 = Anton F.|journal = Frontiers in Microbiology|volume = 5|page = 359|pmid = 25076944|pmc = 4099938}}</ref> and possibly appeared on the Earth about 3.5 billion years ago.<ref>{{cite journal |doi = 10.1073/pnas.0600999103|title = The evolutionary diversification of cyanobacteria: Molecular-phylogenetic and paleontological perspectives|year = 2006|last1 = Tomitani|first1 = A.|last2 = Knoll|first2 = A. H.|last3 = Cavanaugh|first3 = C. M.|last4 = Ohno|first4 = T.|journal = Proceedings of the National Academy of Sciences|volume = 103|issue = 14|pages = 5442–5447|pmid = 16569695|pmc = 1459374|bibcode = 2006PNAS..103.5442T|doi-access = free}}</ref> They are ubiquitous in nature and thrive in a variety of ecological niches ranging from desert to hot springs and ice-cold water. Cyanobacteria are an immense source of several secondary natural products with applications in the food, pharmaceuticals, cosmetics, agriculture, and energy sectors.<ref>{{cite journal |doi = 10.1016/j.biotechadv.2009.04.009|title = Biotechnological and industrial significance of cyanobacterial secondary metabolites|year = 2009|last1 = Rastogi|first1 = Rajesh P.|last2 = Sinha|first2 = Rajeshwar P.|journal = Biotechnology Advances|volume = 27|issue = 4|pages = 521–539|pmid = 19393308}}</ref> Moreover, some species of cyanobacteria grow vigorously and form a dominant microflora in terms of their biomass and productivity in specific ecosystems. Bloom formations due to excessive growth of certain cyanobacteria followed by the production of toxic compounds have been reported in many [[eutrophic]] to [[hypertrophic]] lakes, ponds, and rivers throughout the world.<ref name=Rastogi2014>{{cite journal |doi = 10.1007/s11157-014-9334-6|title = The cyanotoxin-microcystins: Current overview|year = 2014|last1 = Rastogi|first1 = Rajesh P.|last2 = Sinha|first2 = Rajeshwar P.|last3 = Incharoensakdi|first3 = Aran|journal = Reviews in Environmental Science and Bio/Technology|volume = 13|issue = 2|pages = 215–249|s2cid = 84452003}}</ref><ref name=Rastogi2015 />

A range of toxic [[secondary compound]]s, called cyanotoxins, have been reported from cyanobacteria inhabiting freshwater and marine ecosystems. These toxic compounds are highly detrimental for survival of several aquatic organisms, wild and/or domestic animals, and humans. Aquatic organisms, including plants and animals, as well as [[phytoplankton]] and [[zooplankton]] inhabiting under toxic bloom rich ecosystems, are directly exposed to the harmful effects of different cyanotoxins. The intoxication occurring in wild and/or domestic animals and humans is either due to direct ingestion of cells of toxin producing cyanobacteria or the consumption of drinking water contaminated with cyanotoxins.<ref name=Rastogi2014 /> The toxicity of different cyanotoxins is directly proportional to the growth of cyanobacteria and the extent of their toxin production. It has been shown that the growth of different cyanobacteria and their toxin biosynthesis is greatly influenced by different abiotic factors such as light intensity, temperature, short wavelength radiations, pH, and nutrients.<ref name=Neilan2013>{{cite journal |doi = 10.1111/j.1462-2920.2012.02729.x|title = Environmental conditions that influence toxin biosynthesis in cyanobacteria|year = 2013|last1 = Neilan|first1 = Brett A.|last2 = Pearson|first2 = Leanne A.|last3 = Muenchhoff|first3 = Julia|last4 = Moffitt|first4 = Michelle C.|last5 = Dittmann|first5 = Elke|journal = Environmental Microbiology|volume = 15|issue = 5|pages = 1239–1253|pmid = 22429476|doi-access = free}}</ref><ref>{{cite journal |doi = 10.1039/c3pp50418b|title = Productivity of aquatic primary producers under global climate change|year = 2014|last1 = Häder|first1 = Donat-P.|last2 = Villafañe|first2 = Virginia E.|last3 = Helbling|first3 = E. Walter|journal = Photochem. Photobiol. Sci.|volume = 13|issue = 10|pages = 1370–1392|pmid = 25191675|doi-access = free|hdl = 11336/24725|hdl-access = free}}</ref><ref name=Rastogi2014 /> Global warming and temperature gradients can significantly change species composition and favor blooms of toxic phytoplanktons.<ref name=ElShehawy2012>{{cite journal |doi = 10.1016/j.watres.2011.11.021|title = Global warming and hepatotoxin production by cyanobacteria: What can we learn from experiments?|year = 2012|last1 = El-Shehawy|first1 = Rehab|last2 = Gorokhova|first2 = Elena|last3 = Fernández-Piñas|first3 = Francisca|last4 = Del Campo|first4 = Francisca F.|journal = Water Research|volume = 46|issue = 5|pages = 1420–1429|pmid = 22178305| bibcode=2012WatRe..46.1420E }}</ref><ref>{{cite journal |doi = 10.3389/fenvs.2015.00014|doi-access = free|title = Interactions of anthropogenic stress factors on marine phytoplankton|year = 2015|last1 = Hã¤Der|first1 = Donat-P.|last2 = Gao|first2 = Kunshan|journal = Frontiers in Environmental Science|volume = 3}}</ref><ref name=Rastogi2015 />

It has been assumed that cyanotoxins play an important role in [[chemical defense]] mechanisms giving survival advantages to the cyanobacteria over other microbes or deterring predation by higher [[trophic level]]s.<ref>{{cite journal |doi = 10.1016/j.toxicon.2006.11.017|title = Reciprocal allelopathic responses between toxic cyanobacteria (Microcystis aeruginosa) and duckweed (Lemna japonica)|year = 2007|last1 = Jang|first1 = Min-Ho|last2 = Ha|first2 = Kyong|last3 = Takamura|first3 = Noriko|journal = Toxicon|volume = 49|issue = 5|pages = 727–733|pmid = 17207510}}</ref><ref>{{cite journal |doi = 10.3390/md20080007|doi-access = free|title = Cyanobacterial Toxins as Allelochemicals with Potential Applications as Algaecides, Herbicides and Insecticides|year = 2008|last1 = Berry|first1 = John P.|last2 = Gantar|first2 = M.|last3 = Perez|first3 = M. H.|last4 = Berry|first4 = G.|last5 = Noriega|first5 = F. G.|journal = Marine Drugs|volume = 6|issue = 2|pages = 117–146|pmid = 18728763|pmc = 2525484}}</ref> Cyanotoxins may also take part in [[Cell signalling|chemical signalling]].<ref name=Rastogi2015 />

Cyanotoxins are produced by [[cyanobacteria]], a [[phylum (biology)|phylum]] of [[bacteria]] that obtain their energy through [[photosynthesis]]. The prefix ''[[cyan]]'' comes from the [[Greek language|Greek]] {{lang|grc|κύανoς}} meaning "a dark blue substance",<ref>[https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dku%2Fanos κύανος], Henry George Liddell, Robert Scott, ''A Greek-English Lexicon'', on Perseus</ref> and usually indicates any of a number of colours in the blue/green range of the spectrum. Cyanobacteria are commonly referred to as ''blue-green algae''. Traditionally they were thought of as a form of algae, and were introduced as such in older textbooks. However modern sources tend to regard this as outdated;<ref name="IntroBot">{{cite book|last=Nabors|first=Murray W.|year=2004|title=Introduction to Botany|publisher=Pearson Education, Inc|location=San Francisco, CA|isbn=978-0-8053-4416-5}}</ref> they are now considered to be more closely related to bacteria,<ref>Ed. Guiry, M.D., John, D.M., Rindi, F and McCarthy, T.K. 2007. ''New Survey of Clare Island Volume 6: The Freshwater and Terrestrial Algae.'' Royal Irish Academy. {{ISBN|978-1-904890-31-7}}</ref> and the term for true ''[[algae]]'' is restricted to [[Eukaryote|eukaryotic]] organisms.<ref name="Allaby 92">{{cite encyclopedia|veditors = Allaby M|year=1992|encyclopedia=The Concise Dictionary of Botany|publisher=Oxford University Press|location=Oxford|title=Algae}}</ref> Like true algae, cyanobacteria are [[photosynthesize|photosynthetic]] and contain [[photosynthetic pigment]]s, which is why they are usually green or blue.

Cyanobacteria are found almost everywhere; in oceans, lakes and rivers as well as on land. They flourish in Arctic and Antarctic lakes,<ref>Skulberg OM (1996) "Terrestrial and limnic algae and cyanobacteria". In: ''A Catalogue of Svalvard Plants, Fungi, Algae and Cyanobacteria'', Part 9, A Elvebakk and P Prestud (eds.) Norsk Polarinstitutt Skrifter, '''198''': 383-395.</ref> hotsprings<ref>{{cite book |last=Castenholz |first=R. A. |year=1973 |chapter=Ecology of blue-green algae in hotsprings |title=The Biology of Blue-green algae |editor-first=N. G. |editor-last=Carr |editor2-first=B. A. |editor2-last=Whitton |pages=379–414 |publisher=Blackwell |location=Oxford |isbn=0-632-09040-5 }}</ref> and [[wastewater]] treatment plants.<ref>{{cite journal |vauthors=Vasconcelos VM, Pereira E | year = 2001 | title = Cyanobacteria diversity and toxicity in a Wastewater Treatment Plant (Portugal) | journal = Water Research | volume = 35 | issue = 5| pages = 1354–1357 | doi = 10.1016/S0043-1354(00)00512-1 | pmid = 11268858 | bibcode = 2001WatRe..35.1354V }}</ref> They even inhabit the fur of polar bears, to which they impart a greenish tinge.<ref name="Karp G (2009)">{{cite book|author=Gerald Karp|title=Cell and Molecular Biology: Concepts and Experiments|url=https://books.google.com/books?id=arRGYE0GxRQC&pg=PA14|access-date=26 January 2011|date=19 October 2009|publisher=John Wiley and Sons|isbn=978-0-470-48337-4|pages=14–}}</ref> Cyanobacteria produce potent toxins, but they also produce helpful [[Bioactive compound|bioactive]] compounds, including substances with antitumour, antiviral, anticancer, antibiotic and antifungal activity, UV protectants and specific [[enzyme inhibitor|inhibitors of enzymes]].<ref name="Herrero">{{Cite book |last1=Herrero |first1=Antonia |title=The Cyanobacteria: Molecular Biology, Genomics and Evolution |last2=Flores |first2=Enrique |publisher=Caister Academic Press |year=2008 |isbn=978-1-904455-15-8}}</ref><ref name="Sivonen&Jones" />