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Cyanobacteria ▢ᦓ｜Definition｜1st｜20260615164340-00-⌔
Cyanobacteria
Cyanobacteria (/saɪˌænoʊbækˈtɪəriə/sy-AN-oh-bak-TEER-ee-ə) are a group of autotrophic gram-negative bacteria1 of the phylum Cyanobacteriota[^1] that can obtain biological energy via oxygenic photosynthesis. Cyanobacteria originated in a freshwater or terrestrial environment, and first appeared in the middle Archean eon.2 They are probably the most numerous taxon to have ever existed on Earth.3 The name “cyanobacteria” (from Ancient Greek κύανος * (kúanos)* ‘blue’) refers to their bluish green (cyan) color,45 which forms the basis of cyanobacteria’s informal common name, blue-green algae.6789
Cyanobacteria are the first organisms known to have produced oxygen.10 Their photopigments can absorb the red- and blue-spectrum frequencies of sunlight (thus reflecting a greenish color) to split water molecules into hydrogen ions and oxygen. The hydrogen ions are used to react with carbon dioxide to produce complex organic compounds such as carbohydrates (a process known as carbon fixation), and the oxygen is released as a byproduct. By continuously producing and releasing oxygen over billions of years, cyanobacteria are thought to have converted the early Earth’s anoxic, weakly reducing prebiotic atmosphere, into an oxidizing one with free gaseous oxygen (which previously would have been immediately removed by various surface reductants), resulting in the Great Oxidation Event and the “rusting of the Earth” during the early Proterozoic,11 dramatically changing the composition of life forms on Earth.12 The subsequent adaptation of early single-celled organisms to survive in oxygenous environments likely led to endosymbiosis between anaerobes and aerobes, and hence the evolution of eukaryotes during the Paleoproterozoic.
Cyanobacteria use photosynthetic pigments such as various forms of chlorophyll, carotenoids and phycobilins to convert the photonic energy in sunlight to chemical energy. Unlike heterotrophic prokaryotes, cyanobacteria have internal membranes. These are flattened sacs called thylakoids where photosynthesis is performed.1314 Photoautotrophic eukaryotes such as red algae, green algae and plants perform photosynthesis in chlorophyllic organelles that are thought to have their ancestry in cyanobacteria, acquired long ago via endosymbiosis. These endosymbiont cyanobacteria in eukaryotes then evolved and differentiated into specialized organelles such as chloroplasts, chromoplasts, etioplasts, and leucoplasts, collectively known as plastids.
The cyanobacteria Synechocystis and Cyanothece are important model organisms with potential applications in biotechnology for bioethanol production, food colorings, as a source of human and animal food, dietary supplements and raw materials.15 Cyanobacteria produce a range of toxins known as cyanotoxins that can cause harmful health effects in humans and animals. Sericytochromatia, the proposed name of the paraphyletic and most basal group, is the ancestor of both the non-photosynthetic group Melainabacteria and the photosynthetic cyanobacteria, also called Oxyphotobacteria.16
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Sánchez-Baracaldo, Patricia (December 2015). “Origin of marine planktonic cyanobacteria”. Scientific Reports. 5 (1) 17418. Bibcode:2015NatSR…517418S. doi:10.1038/srep17418. PMC 4665016. PMID 26621203. ↩
Stal LJ, Cretoiu MS (2016). The Marine Microbiome: An Untapped Source of Biodiversity and Biotechnological Potential. Springer Science+Business Media. ISBN 978-3-319-33000-6. ↩
Harper, Douglas. “cyan”. Online Etymology Dictionary. Retrieved 21 January 2018. ↩
κύανος. Liddell, Henry George; Scott, Robert; A Greek–English Lexicon at the Perseus Project. ↩
“Life History and Ecology of Cyanobacteria”. University of California Museum of Paleontology. Archived from the original on 19 September 2012. Retrieved 17 July 2012. ↩
“Taxonomy Browser – Cyanobacteria”. National Center for Biotechnology Information. NCBI:txid1117. Retrieved 12 April 2018. ↩
Allaby M, ed. (1992). “Algae”. The Concise Dictionary of Botany. Oxford: Oxford University Press. ↩
Some authors restrict the term algae to protists (eukaryotes), which does not extend to cyanobacteria, which are prokaryotes. However, the majority continue to refer to cyanobacteria as a type of algae. ↩
Crockford PW, Bar On YM, Ward LM, Milo R, Halevy I (November 2023). “The geologic history of primary productivity”. Current Biology. 33 (21): 4741–4750.e5. Bibcode:2023CBio…33E4741C. doi:10.1016/j.cub.2023.09.040. PMID 37827153. ↩
Whitton BA, ed. (2012). “The fossil record of cyanobacteria”. Ecology of Cyanobacteria II: Their Diversity in Space and Time. Springer Science+Business Media. p. 17. ISBN 978-94-007-3855-3. ↩
“Bacteria”. Basic Biology. 18 March 2016. ↩
Liberton M, Pakrasi HB (2008). “Chapter 10. Membrane Systems in Cyanobacteria”. In Herrero A, Flore E (eds.). The Cyanobacteria: Molecular Biology, Genomics, and Evolution. Norwich, United Kingdom: Horizon Scientific Press. pp. 217–287. ISBN 978-1-904455-15-8. ↩
Liberton M, Page LE, O’Dell WB, O’Neill H, Mamontov E, Urban VS, Pakrasi HB (February 2013). “Organization and flexibility of cyanobacterial thylakoid membranes examined by neutron scattering”. The Journal of Biological Chemistry. 288 (5): 3632–3640. doi:10.1074/jbc.M112.416933. PMC 3561581. PMID 23255600. ↩
Pathak J, Rajneesh, Maurya PK, Singh SP, Haeder DP, Sinha RP (2018). “Cyanobacterial Farming for Environment Friendly Sustainable Agriculture Practices: Innovations and Perspectives”. Frontiers in Environmental Science. 6 7. Bibcode:2018FrEnS…6…7P. doi:10.3389/fenvs.2018.00007. ↩
Monchamp ME, Spaak P, Pomati F (27 July 2019). “Long Term Diversity and Distribution of Non-photosynthetic Cyanobacteria in Peri-Alpine Lakes”. Frontiers in Microbiology. 9 3344. doi:10.3389/fmicb.2018.03344. PMC 6340189. PMID 30692982. ↩
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