Editing Cyanobacteria (section)

== Overview ==
[[File:Ocean mist and spray 2.jpg|thumb|upright=1.35|right| Cyanobacteria are found almost everywhere. [[Sea spray]] containing [[marine microorganisms]], including cyanobacteria, can be swept high into the atmosphere where they become [[aeroplankton]], and can travel the globe before falling back to earth.<ref>{{Cite web | vauthors = Morrison J |title=Living Bacteria Are Riding Earth's Air Currents |url=https://www.smithsonianmag.com/science-nature/living-bacteria-are-riding-earths-air-currents-180957734/ |access-date=2022-08-10 |website=Smithsonian Magazine |language=en|date=11 January 2016}}</ref>]]

Cyanobacteria are a large and diverse phylum of [[photoautotrophic|photosynthetic]] [[prokaryote]]s.<ref>{{cite book |doi=10.1007/978-94-007-3855-3_1 | vauthors = Whitton BA, Potts M |chapter=Introduction to the Cyanobacteria | veditors = Whitton BA |title=Ecology of Cyanobacteria II |year=2012  |pages=1–13 | publisher = Springer | location = Dordrecht |isbn=978-94-007-3854-6}}</ref> They are defined by their unique combination of [[Biological pigment|pigments]] and their ability to perform [[oxygenic photosynthesis]]. They often live in [[Colony (biology)|colonial aggregates]] that can take on a multitude of forms.<ref name="Donkor1991"/> Of particular interest are the [[Filamentous cyanobacteria|filamentous species]], which often dominate the upper layers of [[microbial mat]]s found in extreme environments such as [[hot spring]]s, [[hypersaline|hypersaline water]], deserts and the polar regions,<ref name="Stal2000book">{{Cite book | vauthors = Stay LJ | chapter = Cyanobacterial Mats and Stromatolites | chapter-url = https://books.google.com/books?id=4oJ_vi27s18C&q=Stal+LJ+%282000%29+%22Cyanobacterial+Mats+and+Stromatolites%22 |title=Ecology of Cyanobacteria II: Their Diversity in Space and Time | veditors = Whitton BA |date=5 July 2012 |publisher=Springer Science & Business Media |isbn=9789400738553 |access-date=15 February 2022|via=Google Books}}</ref> but are also widely distributed in more mundane environments as well.<ref name=Tamulonis2011>{{cite journal | vauthors = Tamulonis C, Postma M, Kaandorp J | title = Modeling filamentous cyanobacteria reveals the advantages of long and fast trichomes for optimizing light exposure | journal = PLOS ONE | volume = 6 | issue = 7 | pages = e22084 | year = 2011 | pmid = 21789215 | pmc = 3138769 | doi = 10.1371/journal.pone.0022084 | doi-access = free | bibcode = 2011PLoSO...622084T }} {{Creative Commons text attribution notice|cc=by4|from this source=yes}}</ref> They are evolutionarily optimized for environmental conditions of low oxygen.<ref>{{Cite news |url=http://www.latimes.com/news/local/oceans/la-me-ocean30jul30,0,6670018,full.story |archive-url=https://web.archive.org/web/20060814091723/http://www.latimes.com/news/local/oceans/la-me-ocean30jul30,0,6670018,full.story |url-status=dead |archive-date=2006-08-14 |work=[[Los Angeles Times]] |title=A Primeval Tide of Toxins | vauthors = Weiss KR |date=2006-07-30}}</ref> Some species are [[nitrogen-fixing]] and live in a wide variety of moist soils and water, either freely or in a symbiotic relationship with plants or [[lichen]]-forming [[Fungus|fungi]] (as in the lichen genus ''[[Peltigera]]'').<ref>{{cite journal |vauthors=Dodds WK, Gudder DA, Mollenhauer D |year=1995 |title=The ecology of 'Nostoc' |journal=Journal of Phycology |volume=31 |issue=1 |pages=2–18 |doi=10.1111/j.0022-3646.1995.00002.x |bibcode=1995JPcgy..31....2D }}</ref>

[[File:Prochlorococcus marinus.jpg|thumb|upright=1.35|right| {{center|''[[Prochlorococcus]]'', an influential marine cyanobacterium which produces much of the world's oxygen}}]]

Cyanobacteria are globally widespread photosynthetic prokaryotes and are major contributors to global [[biogeochemical cycle]]s.<ref name=Aguilera2021 /> They are the only oxygenic photosynthetic prokaryotes, and prosper in diverse and extreme habitats.<ref>{{cite book |doi=10.1007/978-94-007-3855-3_17 |chapter=Carbon |title=Ecology of Cyanobacteria II |date=2012 |last1=Raven |first1=John A. |pages=443–460 |publisher=Springer |location=Dordrecht |isbn=978-94-007-3854-6 }}</ref> They are among the oldest organisms on Earth with fossil records dating back at least 2.1 billion years.<ref name="Schirrmeister-2013" /> Since then, cyanobacteria have been essential players in the Earth's ecosystems. Planktonic cyanobacteria are a fundamental component of [[marine food web]]s and are major contributors to global [[carbon cycle|carbon]] and [[nitrogen cycle|nitrogen fluxes]].<ref>{{cite journal | vauthors = Bullerjahn GS, Post AF | title = Physiology and molecular biology of aquatic cyanobacteria | journal = Frontiers in Microbiology | volume = 5 | pages = 359 | year = 2014 | pmid = 25076944 | pmc = 4099938 | doi = 10.3389/fmicb.2014.00359 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Tang W, Wang S, Fonseca-Batista D, Dehairs F, Gifford S, Gonzalez AG, Gallinari M, Planquette H, Sarthou G, Cassar N | display-authors = 6 | title = Revisiting the distribution of oceanic N<sub>2</sub> fixation and estimating diazotrophic contribution to marine production | journal = Nature Communications | volume = 10 | issue = 1 | pages = 831 | date = February 2019 | pmid = 30783106 | pmc = 6381160 | doi = 10.1038/s41467-019-08640-0 }}</ref> Some cyanobacteria form [[harmful algal bloom]]s causing the disruption of aquatic ecosystem services and intoxication of wildlife and humans by the production of powerful toxins ([[cyanotoxin]]s) such as [[microcystin]]s, [[saxitoxin]], and [[cylindrospermopsin]].<ref>{{cite journal | vauthors = Bláha L, Babica P, Maršálek B | title = Toxins produced in cyanobacterial water blooms - toxicity and risks | journal = Interdisciplinary Toxicology | volume = 2 | issue = 2 | pages = 36–41 | date = June 2009 | pmid = 21217843 | pmc = 2984099 | doi = 10.2478/v10102-009-0006-2 }}</ref><ref name=Paerl2013>{{cite journal | vauthors = Paerl HW, Otten TG | title = Harmful cyanobacterial blooms: causes, consequences, and controls | journal = Microbial Ecology | volume = 65 | issue = 4 | pages = 995–1010 | date = May 2013 | pmid = 23314096 | doi = 10.1007/s00248-012-0159-y | bibcode = 2013MicEc..65..995P }}</ref> Nowadays, cyanobacterial blooms pose a serious threat to aquatic environments and public health, and are increasing in frequency and magnitude globally.<ref name=Huisman2018 /><ref name=Aguilera2021 />

Cyanobacteria are ubiquitous in marine environments and play important roles as [[primary producer]]s. They are part of the marine [[phytoplankton]], which currently contributes almost half of the Earth's total primary production.<ref>{{cite journal | vauthors = Field CB, Behrenfeld MJ, Randerson JT, Falkowski P | title = Primary production of the biosphere: integrating terrestrial and oceanic components | journal = Science | volume = 281 | issue = 5374 | pages = 237–240 | date = July 1998 | pmid = 9657713 | doi = 10.1126/science.281.5374.237 | bibcode = 1998Sci...281..237F | url = https://www.escholarship.org/uc/item/9gm7074q }}</ref> About 25% of the global marine primary production is contributed by cyanobacteria.<ref>{{cite journal | vauthors = Cabello-Yeves PJ, Scanlan DJ, Callieri C, Picazo A, Schallenberg L, Huber P, Roda-Garcia JJ, Bartosiewicz M, Belykh OI, Tikhonova IV, Torcello-Requena A, De Prado PM, Millard AD, Camacho A, Rodriguez-Valera F, Puxty RJ | display-authors = 6 | title = α-cyanobacteria possessing form IA RuBisCO globally dominate aquatic habitats | journal = The ISME Journal | volume = 16 | issue = 10 | pages = 2421–2432 | date = October 2022 | pmid = 35851323 | pmc = 9477826 | doi = 10.1038/s41396-022-01282-z | publisher = Springer Science and Business Media LLC | bibcode = 2022ISMEJ..16.2421C }} {{Creative Commons text attribution notice|cc=by4|from this source=yes}}</ref>

Within the cyanobacteria, only a few lineages colonized the open ocean: ''[[Crocosphaera]]'' and relatives, [[cyanobacterium UCYN-A]], ''[[Trichodesmium]]'', as well as ''[[Prochlorococcus]]'' and ''[[Synechococcus]]''.<ref name=Zehr2011>{{cite journal | vauthors = Zehr JP | title = Nitrogen fixation by marine cyanobacteria | journal = Trends in Microbiology | volume = 19 | issue = 4 | pages = 162–173 | date = April 2011 | pmid = 21227699 | doi = 10.1016/j.tim.2010.12.004 }}</ref><ref name=Thompson2012>{{cite journal | vauthors = Thompson AW, Foster RA, Krupke A, Carter BJ, Musat N, Vaulot D, Kuypers MM, Zehr JP | display-authors = 6 | title = Unicellular cyanobacterium symbiotic with a single-celled eukaryotic alga | journal = Science | volume = 337 | issue = 6101 | pages = 1546–1550 | date = September 2012 | pmid = 22997339 | doi = 10.1126/science.1222700 | bibcode = 2012Sci...337.1546T }}</ref><ref name=Johnson2006>{{cite journal | vauthors = Johnson ZI, Zinser ER, Coe A, McNulty NP, Woodward EM, Chisholm SW | title = Niche partitioning among Prochlorococcus ecotypes along ocean-scale environmental gradients | journal = Science | volume = 311 | issue = 5768 | pages = 1737–1740 | date = March 2006 | pmid = 16556835 | doi = 10.1126/science.1118052 | bibcode = 2006Sci...311.1737J }}</ref><ref name=Scanlan2009>{{cite journal | vauthors = Scanlan DJ, Ostrowski M, Mazard S, Dufresne A, Garczarek L, Hess WR, Post AF, Hagemann M, Paulsen I, Partensky F | display-authors = 6 | title = Ecological genomics of marine picocyanobacteria | journal = Microbiology and Molecular Biology Reviews | volume = 73 | issue = 2 | pages = 249–299 | date = June 2009 | pmid = 19487728 | pmc = 2698417 | doi = 10.1128/MMBR.00035-08 }}</ref> From these lineages, nitrogen-fixing cyanobacteria are particularly important because they exert a control on [[Marine primary production|primary productivity]] and the [[Biological pump|export of organic carbon]] to the deep ocean,<ref name=Zehr2011 /> by converting nitrogen gas into ammonium, which is later used to make amino acids and proteins. Marine [[picocyanobacteria]] (''[[Prochlorococcus]]'' and ''[[Synechococcus]]'') numerically dominate most phytoplankton assemblages in modern oceans, contributing importantly to primary productivity.<ref name=Johnson2006 /><ref name=Scanlan2009 /><ref name="Present and future global distribut">{{cite journal | vauthors = Flombaum P, Gallegos JL, Gordillo RA, Rincón J, Zabala LL, Jiao N, Karl DM, Li WK, Lomas MW, Veneziano D, Vera CS, Vrugt JA, Martiny AC | display-authors = 6 | title = Present and future global distributions of the marine Cyanobacteria Prochlorococcus and Synechococcus | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 110 | issue = 24 | pages = 9824–9829 | date = June 2013 | pmid = 23703908 | pmc = 3683724 | doi = 10.1073/pnas.1307701110 | doi-access = free | bibcode = 2013PNAS..110.9824F }}</ref> While some planktonic cyanobacteria are unicellular and free living cells (e.g., ''Crocosphaera'', ''Prochlorococcus'', ''Synechococcus''); others have established symbiotic relationships with [[Haptophyte|haptophyte algae]], such as [[coccolithophore]]s.<ref name=Thompson2012 /> Amongst the filamentous forms, ''Trichodesmium'' are free-living and form aggregates. However, filamentous heterocyst-forming cyanobacteria (e.g., ''[[Richelia]]'', ''[[Calothrix]]'') are found in association with [[diatom]]s such as ''Hemiaulus'', ''Rhizosolenia'' and ''[[Chaetoceros]]''.<ref>{{cite journal | vauthors = Foster RA, Kuypers MM, Vagner T, Paerl RW, Musat N, Zehr JP | title = Nitrogen fixation and transfer in open ocean diatom-cyanobacterial symbioses | journal = The ISME Journal | volume = 5 | issue = 9 | pages = 1484–1493 | date = September 2011 | pmid = 21451586 | pmc = 3160684 | doi = 10.1038/ismej.2011.26 | bibcode = 2011ISMEJ...5.1484F }}</ref><ref>{{cite journal |doi=10.1111/j.1439-0485.1990.tb00233.x |title=Laboratory Culture and Preliminary Characterization of the Nitrogen-Fixing Rhizosolenia-Richelia Symbiosis |year=1990 | vauthors = Villareal TA |journal=Marine Ecology |volume=11 |issue=2 |pages=117–132 |bibcode=1990MarEc..11..117V}}</ref><ref>{{cite journal | vauthors = Janson S, Wouters J, Bergman B, Carpenter EJ | title = Host specificity in the Richelia-diatom symbiosis revealed by hetR gene sequence analysis | journal = Environmental Microbiology | volume = 1 | issue = 5 | pages = 431–438 | date = October 1999 | pmid = 11207763 | doi = 10.1046/j.1462-2920.1999.00053.x | bibcode = 1999EnvMi...1..431J }}</ref><ref name="Sánchez-Baracaldo2016" />

Marine cyanobacteria include the smallest known photosynthetic organisms. The smallest of all, ''[[Prochlorococcus]]'', is just 0.5 to 0.8 micrometres across.<ref>{{cite journal | vauthors = Kettler GC, Martiny AC, Huang K, Zucker J, Coleman ML, Rodrigue S, Chen F, Lapidus A, Ferriera S, Johnson J, Steglich C, Church GM, Richardson P, Chisholm SW | display-authors = 6 | title = Patterns and implications of gene gain and loss in the evolution of Prochlorococcus | journal = PLOS Genetics | volume = 3 | issue = 12 | pages = e231 | date = December 2007 | pmid = 18159947 | pmc = 2151091 | doi = 10.1371/journal.pgen.0030231 | doi-access = free }}</ref> In terms of numbers of individuals, ''Prochlorococcus'' is possibly the most plentiful genus on Earth: a single millilitre of surface seawater can contain 100,000 cells of this genus or more. Worldwide there are estimated to be several [[octillion]] (10<sup>27</sup>, a billion billion billion) individuals.<ref>{{Cite journal |last1=Flombaum |first1=Pedro |last2=Gallegos |first2=José L. |last3=Gordillo |first3=Rodolfo A. |last4=Rincón |first4=José |last5=Zabala |first5=Lina L. |last6=Jiao |first6=Nianzhi |last7=Karl |first7=David M. |last8=Li |first8=William K. W. |last9=Lomas |first9=Michael W. |last10=Veneziano |first10=Daniele |last11=Vera |first11=Carolina S. |last12=Vrugt |first12=Jasper A. |last13=Martiny |first13=Adam C. |date=2013-06-11 |title=Present and future global distributions of the marine Cyanobacteria Prochlorococcus and Synechococcus |journal=Proceedings of the National Academy of Sciences |volume=110 |issue=24 |pages=9824–9829 |doi=10.1073/pnas.1307701110 |doi-access=free |pmc=3683724 |pmid=23703908|bibcode=2013PNAS..110.9824F }}</ref> ''Prochlorococcus'' is ubiquitous between latitudes 40°N and 40°S, and dominates in the [[oligotroph]]ic (nutrient-poor) regions of the oceans.<ref name="Partensky-1999">{{cite journal | vauthors = Partensky F, Hess WR, Vaulot D | title = Prochlorococcus, a marine photosynthetic prokaryote of global significance | journal = Microbiology and Molecular Biology Reviews | volume = 63 | issue = 1 | pages = 106–127 | date = March 1999 | pmid = 10066832 | pmc = 98958 | doi = 10.1128/MMBR.63.1.106-127.1999 }}</ref> The bacterium accounts for about 20% of the oxygen in the Earth's atmosphere.<ref name="npr">{{cite news |last1=Palca |first1=Joe |title=The Most Important Microbe You've Never Heard Of |url=https://www.npr.org/2008/06/12/91448837/the-most-important-microbe-youve-never-heard-of |work=NPR |date=12 June 2008 }}</ref>