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Cyanobacteria (), also known as Cyanophyta, are a
phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of a noun typically denotes a q ...
of
Gram-negative bacteria Gram-negative bacteria are bacteria Bacteria (; common noun bacteria, singular bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), do ...
that obtain energy via
photosynthesis Photosynthesis is a process used by plants and other organisms to convert Conversion or convert may refer to: Arts, entertainment, and media * Conversion (Doctor Who audio), "Conversion" (''Doctor Who'' audio), an episode of the audio drama ' ...

photosynthesis
. The name ''cyanobacteria'' refers to their color (), giving them their other name, "blue-green algae", though modern botanists restrict the term ''
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic Photosynthesis is a process used by plants and other organisms to convert Conversion or convert may refer to: Arts, entertainment, and media * Co ...

algae
'' to
eukaryote Eukaryotes () are organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interact ...

eukaryote
s and do not apply it to cyanobacteria, which are
prokaryote A prokaryote () is a single-celled organism A unicellular organism, also known as a single-celled organism, is an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contig ...
s. They appear to have originated in freshwater or a terrestrial environment. Sericytochromatia, the proposed name of the
paraphyletic In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and all descendants of that ancestor excluding a few—typically only one or two—Monophyly, monophyletic subgroups. The group is said to be paraphyleti ...
and most basal group, is the ancestor of both the non-photosynthetic group
Melainabacteria Melainabacteria is a phylum related to Cyanobacteria Cyanobacteria (), also known as Cyanophyta, are a phylum (biology), phylum of Gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color ...
and the photosynthetic cyanobacteria, also called Oxyphotobacteria. Cyanobacteria use
photosynthetic pigment A photosynthetic pigment (accessory pigment; chloroplast pigment; antenna pigment) is a biological pigment, pigment that is present in chloroplasts or photosynthetic bacterium, bacteria and captures the light energy necessary for photosynthesis. P ...
s, such as
carotenoid Carotenoids (), also called tetraterpenoids, are yellow, orange, and red organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ (anatomy), organ Chemistry * Organ ...
s,
phycobilinPhycobilins (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 millio ...
s, and various forms of
chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally ...

chlorophyll
, which absorb energy from light. Unlike
heterotroph A heterotroph (; from Ancient Greek Ancient Greek includes the forms of the Greek language Greek ( el, label=Modern Greek Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as Greek ...
ic prokaryotes, cyanobacteria have
internal membranes
internal membranes
. These are flattened sacs called
thylakoids Thylakoids are membrane-bound compartments inside chloroplasts and cyanobacterium, cyanobacteria. They are the site of the light-dependent reactions of photosynthesis. Thylakoids consist of a thylakoid membrane surrounding a thylakoid lumen (ana ...
where photosynthesis is performed.
Phototroph Terrestrial and aquatic phototrophs: plants grow on a fallen log floating in algae-rich water Phototrophs ('' Gr'': φῶς, φωτός = light, τροϕή = nourishment) are organism In biology, an organism (from Ancient Greek, Greek: ...
ic eukaryotes such as green plants perform photosynthesis in
plastid The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle In cell biology, an organelle is a specialized subunit, usually within a cell (biology), cell, that has a specific function. The name ' ...
s that are thought to have their ancestry in cyanobacteria, acquired long ago via a process called
endosymbiosis An endosymbiont or endobiont is any organism that lives within the body or cells of another organism most often, though not always, in a mutualism (biology), mutualistic relationship. (The term endosymbiosis is from the Greek language, Greek: ...

endosymbiosis
. These endosymbiotic cyanobacteria in eukaryotes then evolved and differentiated into specialized
organelle In cell biology Cell biology (also cellular biology or cytology) is a branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, ...
s such as
chloroplast A chloroplast is a type of membrane-bound organelle In cell biology, an organelle is a specialized subunit, usually within a cell (biology), cell, that has a specific function. The name ''organelle'' comes from the idea that these structure ...

chloroplast
s,
etioplastImage:Plastids_types.svg, Different types of plastid Etioplasts are chloroplasts that have not been exposed to light. They are usually found in flowering plants (Angiosperms) grown in the dark. If a plant is kept out of light for several days, its n ...
s and
leucoplast s Leucoplasts (λευκός leukós "white", πλαστός plastós "formed, molded") are a category of plastid The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle found in the cells o ...
s. Cyanobacteria are the first organisms known to have produced oxygen. By producing and releasing oxygen as a byproduct of photosynthesis, cyanobacteria are thought to have converted the early oxygen-poor,
reducing atmosphere A reducing atmosphere is an atmospheric An atmosphere (from the greek words ἀτμός ''(atmos)'', meaning 'vapour', and σφαῖρα ''(sphaira)'', meaning 'ball' or 'sphere') is a layer or a set of layers of gases surrounding a planet ...
into an
oxidizing Redox (reduction–oxidation, pronunciation: or ) is a type of chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substance A chemical substance is a form of matter ...

oxidizing
one, causing the
Great Oxygenation Event The Great Oxidation Event (GOE), also called the Great Oxygenation Event, the Oxygen catastrophe, and the Oxygen Crisis, was a time interval when the Earth's atmosphere The atmosphere of Earth is the layer of gas Gas is one of the ...
and the "rusting of the Earth", which dramatically changed the composition of the Earth's life forms and led to the near-extinction of
anaerobic organism An anaerobic organism or anaerobe is any organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties of life. It is a syn ...
s. The cyanobacteria ''
Synechocystis ''Synechocystis'' is a genus of unicellular, freshwater cyanobacteria Cyanobacteria , also known as Cyanophyta, are a phylum of Gram-negative bacteria Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in ...

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. Cyanobacteria produce a range of toxins known as cyanotoxins that can pose a danger to humans and animals.


Overview

Cyanobacteria are a very large and diverse phylum of
photoautotrophicPhotoautotrophs are organisms that use light energy Light or visible light is electromagnetic radiation In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis' ...
prokaryote A prokaryote () is a single-celled organism A unicellular organism, also known as a single-celled organism, is an organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contig ...
s. They are defined by their unique combination of
pigments A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compound , CH4; is among the simplest organic compou ...
and their ability to perform oxygenic photosynthesis. They often live in colonial aggregates that can take on a multitude of forms. Of particular interest are the filamentous species, which often dominate the upper layers of
microbial mat The cyanobacterial algal mat, salty lake on the White Sea">algal_mat.html" ;"title="cyanobacterial algal mat">cyanobacterial algal mat, salty lake on the White Sea seaside A microbial mat is a multi-layered sheet of microorganisms, mainly bacteria ...
s found in extreme environments such as
hot spring A hot spring, hydrothermal spring, or geothermal spring is a spring Spring(s) may refer to: Common uses * Spring (season), a season of the year * Spring (device), a mechanical device that stores energy * Spring (hydrology), a natural source of w ...

hot spring
s, hypersaline water, deserts and the polar regions,Stal LJ (2000) "Cyanobacterial Mats and Stromatolites"
/ref> but are also widely distributed in more mundane environments as well. Material was copied from this source, which is available under
Creative Commons Attribution 4.0 International License
Cyanobacteria are a group of photosynthetic bacteria evolutionarily optimized for environmental conditions of low oxygen. 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 A lichen ( , ) is a composite organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecu ...

lichen
-forming
fungi A fungus (plural The plural (sometimes abbreviated An abbreviation (from Latin ''brevis'', meaning ''short'') is a shortened form of a word or phrase, by any method. It may consist of a group of letters, or words taken from the full ...

fungi
(as in the lichen genus ''''). They range from
unicellular A unicellular organism, also known as a single-celled organism, is an organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemica ...
to
filamentous The word filament, which is descended from Latin ''filum'' meaning "Thread (yarn), thread", is used in English for a variety of thread-like structures, including: In commerce * Fiber or, more loosely, yarn * Filament (textiles) In physics and en ...
and include
colonial Colonial or The Colonial may refer to: * Colonial, of, relating to, or characteristic of a colony or colony (biology) Architecture * American colonial architecture * French Colonial * Spanish Colonial architecture Automobiles * Colonial (1920 auto ...
species. Colonies may form filaments, sheets, or even hollow spheres. Cyanobacteria are globally widespread photosynthetic prokaryotes and are major contributors to global
biogeochemical cycle In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Topics of interest include the bi ...
s. They are the only oxygenic photosynthetic prokaryotes, and prosper in diverse and extreme habitats. They are among the oldest organisms on Earth with fossil records dating back 3.5 billion years. Since then, cyanobacteria have been essential players in the Earth's ecosystems. Planktonic cyanobacteria are a fundamental component of
marine food web Compared to terrestrial environments, marine environments have biomass pyramids which are inverted at the base. In particular, the biomass of consumers (copepods, krill, shrimp, forage fish) is larger than the biomass of primary producers. This ...
s and are major contributors to global
carbon Carbon (from la, carbo "coal") is a with the C and 6. It is lic and —making four s available to form s. It belongs to group 14 of the periodic table. Carbon makes up only about 0.025 percent of Earth's crust. Three occur naturally, ...

carbon
and . Some cyanobacteria form
harmful algal bloom A harmful algal bloom (HAB) contains organisms (usually algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transform ...
s causing the disruption of aquatic ecosystem services and intoxication of wildlife and humans by the production of powerful toxins (
cyanotoxin Cyanotoxins are toxin A toxin is a harmful substance produced within living cells or organisms; synthetic toxicants created by artificial processes are thus excluded. The term was first used by organic chemist Ludwig Brieger (1849–1919), der ...
s) such as
microcystin Microcystins—or cyanoginosins—are a class of toxins produced by certain freshwater blue-green algae. Over 50 different microcystins have been discovered so far, of which microcystin-LR is the most common. Chemically they are cyclic heptapeptid ...
s,
saxitoxin Saxitoxin (STX) is a potent neurotoxin Neurotoxins are toxins that are destructive to nervous tissue, nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insult (medical), insultsSpencer 2 ...

saxitoxin
, and
cylindrospermopsin Cylindrospermopsin (abbreviated to CYN, or CYL) is a cyanotoxin produced by a variety of freshwater cyanobacteria. CYN is a Polycyclic compound, polycyclic uracil derivative (chemistry), derivative containing guanidine, guanidino and sulfate grou ...

cylindrospermopsin
. Nowadays, cyanobacterial blooms pose a serious threat to aquatic environments and public health, and are increasing in frequency and magnitude globally. Cyanobacteria are ubiquitous in marine environments and play important roles as
primary producer Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band) Primary were an Australian electronic rock band which formed in 1995 the Fonti brothers: Jamie on keyboards and Sean on bass guitar (b ...
s. Marine
phytoplankton Phytoplankton () are the autotrophic An autotroph or primary producer is an organism that produces complex organic compound , CH4; is among the simplest organic compounds. In chemistry, organic compounds are generally any chemical compoun ...

phytoplankton
today contribute almost half of the Earth's total primary production. Within the cyanobacteria, only a few lineages colonized the open-ocean (i.e., '' Crocosphaera'' and relatives, cyanobacterium UCYN-A, '' Trichodesmium'', as well as ''
Prochlorococcus ''Prochlorococcus'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also ref ...
'' and ''
Synechococcus ''Synechococcus'' (from the Greek ''synechos'', in succession, and the Greek ''kokkos'', granule) is a unicellular cyanobacterium Cyanobacteria , also known as Cyanophyta, are a phylum In biology, a phylum (; plural The plural (somet ...
''). From these lineages, nitrogen fixing cyanobacteria are particularly important because they exert a control on
primary productivity In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through ...
and the export of organic carbon to the deep ocean, by converting nitrogen gas into ammonium, which is later used to make amino acids and proteins. Marine picocyanobacteria (i.e., ''Prochlorococcus'' and ''Synechococcus'') numerically dominate most phytoplankton assemblages in modern oceans contributing importantly to primary productivity. While some planktonic cyanobacteria are unicellular and free living cells (e.g., ''Crocosphaera'', ''Prochlorococcus'', ''Synechococcus''), others have established symbiotic relationships with haptophyte algae, such as
coccolithophore A coccolithophore (or coccolithophorid, from the adjective) is a Unicellular organism, unicellular, eukaryotic phytoplankton (alga). They belong either to the kingdom Protista, according to Robert Whittaker (ecologist), Robert Whittaker's Kingdom ...
s. Amongst the filamentous forms, ''Trichodesmium'' are free-living and form aggregates. However, filamentous heterocyst-forming cyanobacteria (e.g., ''
Richelia ''Richelia'' is a genus of Nitrogen fixation, nitrogen-fixing Filamentous bacteria, filamentous heterocystous cyanobacteria. It contains the single species ''Richelia intracellularis''. They exist as both free-living organisms as well as Symbiotic ...
'', ''
Calothrix ''Calothrix'' is a genus of cyanobacteria. They are generally found in freshwater. References

Rivulariaceae Cyanobacteria genera {{cyanobacteria-stub ...
'') are found in association with
diatom Diatoms (''diá-tom-os'' 'cut in half', from ''diá'', 'through' or 'apart', and the root of ''tém-n-ō'', 'I cut') are a major group of algae Algae (; singular alga ) is an informal term for a large and diverse group of s. It is a grou ...

diatom
s such as ''Hemiaulus'', ''Rhizosolenia'' and '' Chaetoceros''. Marine cyanobacteria include the smallest known photosynthetic organisms. The smallest of all, ''
Prochlorococcus ''Prochlorococcus'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also ref ...
'', is just 0.5 to 0.8 micrometres across. In terms of individual numbers, ''Prochlorococcus'' is possibly the most plentiful species on Earth: a single millilitre of surface seawater can contain 100,000 cells or more. Worldwide there are estimated to be several octillion (1027) individuals. ''Prochlorococcus'' is ubiquitous between 40°N and 40°S and dominates in the
oligotroph An oligotroph is an organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, ...
ic (nutrient poor) regions of the oceans. The bacterium accounts for about 20% of the oxygen in the Earth's atmosphere.


Morphology

Cyanobacteria present remarkable variability in terms of morphology: from
unicellular A unicellular organism, also known as a single-celled organism, is an organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemica ...
and
colonial Colonial or The Colonial may refer to: * Colonial, of, relating to, or characteristic of a colony or colony (biology) Architecture * American colonial architecture * French Colonial * Spanish Colonial architecture Automobiles * Colonial (1920 auto ...
to filamentous forms. Filamentous forms exhibit functional cell differentiation such as
heterocyst Heterocysts or heterocytes are specialized nitrogen fixation, nitrogen-fixing cells formed during nitrogen starvation by some filamentation, filamentous cyanobacteria, such as ''Nostoc punctiforme'', ''Cylindrospermum stagnale'', and ''Anabaena sph ...
s (for nitrogen fixation),
akinetes An akinete is an enveloped, thick-walled, non-motile, dormant cell (biology), cell formed by filamentous, heterocyst-forming cyanobacteria under the order Nostocales and Stigonematales. Akinetes are resistant to cold and desiccation. They also accu ...
(resting stage cells), and
hormogonia Hormogonia are motile filaments of ...
(reproductive, motile filaments). These, together with the intercellular connections they possess, are considered the first signs of multicellularity. Many cyanobacteria form motile filaments of cells, called
hormogonia Hormogonia are motile filaments of ...
, that travel away from the main biomass to bud and form new colonies elsewhere. The cells in a hormogonium are often thinner than in the vegetative state, and the cells on either end of the motile chain may be tapered. To break away from the parent colony, a hormogonium often must tear apart a weaker cell in a filament, called a necridium. File:Gloeotrichia in Sytox.jpg, Ball-shaped colony of Gloeotrichia echinulata stained with SYTOX File:CyanobacteriaColl1.jpg, Colonies of '' Nostoc pruniforme'' Some filamentous species can differentiate into several different cell types: * vegetative cells – the normal, photosynthetic cells that are formed under favorable growing conditions *
akinete An akinete is an enveloped, thick-walled, non-motile, dormant cell (biology), cell formed by filamentous, heterocyst-forming cyanobacteria under the order Nostocales and Stigonematales. Akinetes are resistant to cold and desiccation. They also accu ...
s – climate-resistant spores that may form when environmental conditions become harsh * thick-walled heterocysts – which contain the enzyme
nitrogenase Nitrogenases are enzymes () that are produced by certain bacteria, such as cyanobacteria (blue-green bacteria). These enzymes are responsible for the Organic redox reaction, reduction of nitrogen (N2) to ammonia (NH3). Nitrogenases are the only ...

nitrogenase
vital for
nitrogen fixation Nitrogen fixation is a chemical process by which molecular nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific st ...
in an anaerobic environment due to its sensitivity to oxygen. Each individual cell (each single cyanobacterium) typically has a thick, gelatinous
cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane cell membrane vs. Prokaryotes The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to a ...
. They lack
flagella A flagellum (; ) is a hairlike appendage that protrudes from a wide range of microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology Biology is the natural science that studies life and ...
, but hormogonia of some species can move about by
gliding Gliding is a recreational activity and competitive air sport The term "air sports" covers a range of aerial activities, including air racing, aerobatics, aeromodelling, hang gliding, human powered aircraft, parachuting, paragliding and skydiv ...

gliding
along surfaces. Many of the multicellular filamentous forms of ''
Oscillatoria ''Oscillatoria'' is a genus of filamentous The word filament, which is descended from Latin ''filum'' meaning "Thread (yarn), thread", is used in English for a variety of thread-like structures, including: In commerce * Fiber or, more loosely ...

Oscillatoria
'' are capable of a waving motion; the filament oscillates back and forth. In water columns, some cyanobacteria float by forming
gas vesicle Gas vesicles, also known as gas vacuoles, are nanocompartments in certain prokaryotic organisms, which help in buoyancy. Gas vesicles are composed entirely of protein Proteins are large biomolecules or macromolecules that are comprised of one ...
s, as in
archaea Archaea ( ; singular archaeon ) constitute a domain Domain may refer to: Mathematics *Domain of a function, the set of input values for which the (total) function is defined **Domain of definition of a partial function **Natural domain of a pa ...

archaea
. These vesicles are not
organelle In cell biology Cell biology (also cellular biology or cytology) is a branch of biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, ...
s as such. They are not bounded by
lipid membranes The lipid bilayer (or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around all cell (biology), cells. The cell membranes of almost all organis ...
but by a protein sheath.


Nitrogen fixation

Some cyanobacteria can fix atmospheric
nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science ...

nitrogen
in anaerobic conditions by means of specialized cells called
heterocyst Heterocysts or heterocytes are specialized nitrogen fixation, nitrogen-fixing cells formed during nitrogen starvation by some filamentation, filamentous cyanobacteria, such as ''Nostoc punctiforme'', ''Cylindrospermum stagnale'', and ''Anabaena sph ...
s. Heterocysts may also form under the appropriate environmental conditions (anoxic) when fixed nitrogen is scarce. Heterocyst-forming species are specialized for nitrogen fixation and are able to fix nitrogen gas into
ammonia Ammonia is a chemical compound, compound of nitrogen and hydrogen with the chemical formula, formula NH3. A Binary compounds of hydrogen, stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct ch ...

ammonia
(),
nitrites The nitrite ion has the chemical formula A chemical formula is a way of presenting information about the chemical proportions of atom An atom is the smallest unit of ordinary matter In classical physics and general chemistry, m ...
() or
nitrates Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalently bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not ze ...
(), which can be absorbed by plants and converted to protein and nucleic acids (atmospheric nitrogen is not
bioavailable In pharmacology Pharmacology is a branch of medicine and pharmaceutical sciences concerned with drug or medication action, where a drug may be defined as any artificial, natural, or endogenous (from within the body) molecule which exerts a bio ...
to plants, except for those having endosymbiotic nitrogen-fixing bacteria, especially the family
Fabaceae The Fabaceae or Leguminosae,International Code of Nomenc ...

Fabaceae
, among others). Free-living cyanobacteria are present in the water of
rice paddies fields in Hanalei Valley, Kaua'i, Hawaii A paddy field is a flooded field (agriculture), field of arable land used for growing Aquatic plant, semiaquatic crops, most notably rice and taro. It originates from the Neolithic rice-farming cul ...

rice paddies
, and cyanobacteria can be found growing as
epiphyte An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. Epiphytes take part in nutrient cycles and add to both ...

epiphyte
s on the surfaces of the green alga, '' Chara'', where they may fix nitrogen. Cyanobacteria such as ''
Anabaena ''Anabaena'' is a genus of Filamentation, filamentous cyanobacteria that exist as plankton. They are known for nitrogen-fixing abilities, and they form symbiosis, symbiotic relationships with certain plants, such as the mosquito fern. They are one ...
'' (a symbiont of the aquatic fern ''
Azolla ''Azolla'' (mosquito fern, duckweed fern, fairy moss, water fern) is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of ...

Azolla
'') can provide rice plantations with
biofertilizer '' A biofertilizer (also bio-fertilizer) is a substance which contains living micro-organisms which, when applied to seeds, plant surfaces, or soil, colonize the rhizosphere or the interior of the plant and promotes growth by increasing the supply ...
.


Photosynthesis

Cyanobacteria have several unique features. As the
endosymbiotic An endosymbiont or endobiont is any organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties of life. It is a synony ...
plastids are endosymbiotic cyanobacteria, they share these features to the extent that they have not lost them.


Carbon fixation

Cyanobacteria use the energy of
sunlight Sunlight is a portion of the given off by the , in particular , , and light. On , sunlight is and through , and is obvious as when the Sun is above the . When direct is not blocked by s, it is experienced as sunshine, a combination of b ...

sunlight
to drive
photosynthesis Photosynthesis is a process used by plants and other organisms to convert Conversion or convert may refer to: Arts, entertainment, and media * Conversion (Doctor Who audio), "Conversion" (''Doctor Who'' audio), an episode of the audio drama ' ...

photosynthesis
, a process where the energy of light is used to synthesize
organic compound In chemistry Chemistry is the study of the properties and behavior of . It is a that covers the that make up matter to the composed of s, s and s: their composition, structure, properties, behavior and the changes they undergo during ...
s from carbon dioxide. Because they are aquatic organisms, they typically employ several strategies which are collectively known as a " concentrating mechanism" to aid in the acquisition of inorganic carbon ( or
bicarbonate In inorganic chemistry, bicarbonate (International Union of Pure and Applied Chemistry, IUPAC-recommended nomenclature: hydrogen carbonate) is an intermediate form in the deprotonation of carbonic acid. It is a Polyatomic ion, polyatomic anion w ...

bicarbonate
). Among the more specific strategies is the widespread prevalence of the bacterial microcompartments known as
carboxysome Image:Carboxysomes EM.jpg, 460px, Electron micrographs showing alpha-carboxysomes from the chemoautotrophic bacterium ''Halothiobacillus, Halothiobacillus neapolitanus'': (A) arranged within the cell, and (B) intact upon isolation. Scale bars indica ...

carboxysome
s, which co-operate with active transporters of CO2 and bicarbonate, in order to accumulate bicarbonate into the cytoplasm of the cell. Carboxysomes are
icosahedral In geometry Geometry (from the grc, γεωμετρία; ' "earth", ' "measurement") is, with , one of the oldest branches of . It is concerned with properties of space that are related with distance, shape, size, and relative position ...

icosahedral
structures composed of hexameric shell proteins that assemble into cage-like structures that can be several hundreds of nanometres in diameter. It is believed that these structures tether the -fixing enzyme,
RuBisCO Ribulose-1,5-bisphosphate carboxylase-oxygenase, commonly known by the abbreviations RuBisCo, rubisco, RuBPCase, or RuBPco, is an enzyme involved in the first major step of carbon fixation, a process by which atmospheric carbon dioxide is convert ...
, to the interior of the shell, as well as the enzyme
carbonic anhydrase The carbonic anhydrases (or carbonate dehydratases) form a family of enzymes that catalyst, catalyze the interconversion between carbon dioxide and water and the Dissociation (chemistry), dissociated ions of carbonic acid (i.e. bicarbonate and ...

carbonic anhydrase
, using metabolic channeling to enhance the local concentrations and thus increase the efficiency of the RuBisCO enzyme.


Electron transport

In contrast to
purple bacteria Purple bacteria or purple photosynthetic bacteria are Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram stain, gram-staining method of bacterial differentiation. They are characterized ...
and other bacteria performing
anoxygenic photosynthesis Bacterial anoxygenic photosynthesis is differentiated from the more renowned terrestrial plant oxygenic photosynthesis by method of a terminal reductant that is (e.g. hydrogen sulfide Hydrogen sulfide is the chemical compound with the chemical f ...
, thylakoid membranes of cyanobacteria are not continuous with the plasma membrane but are separate compartments. The photosynthetic machinery is embedded in the
thylakoid Thylakoids are membrane-bound compartments inside chloroplast Chloroplasts are organelles that conduct photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in the energy ...

thylakoid
membranes, with phycobilisomes acting as light-harvesting antennae attached to the membrane, giving the green pigmentation observed (with wavelengths from 450 nm to 660 nm) in most cyanobacteria. While most of the high-energy
electron The electron is a subatomic particle (denoted by the symbol or ) whose electric charge is negative one elementary charge. Electrons belong to the first generation (particle physics), generation of the lepton particle family, and are general ...

electron
s derived from water are used by the cyanobacterial cells for their own needs, a fraction of these electrons may be donated to the external environment via
electrogenic __FORCETOC__ Bioelectrogenesis is the generation of electricity by living organisms, a phenomenon that belongs to the science of electrophysiology Electrophysiology (from Greek , ''ēlektron'', "amber" etymology of "electron"">Electron#Etymology ...
activity.


Respiration

Respiration Respiration may refer to: Biology * Cellular respiration, the process in which nutrients are converted into useful energy in a cell ** Anaerobic respiration, cellular respiration without oxygen ** Maintenance respiration, the amount of cellular ...

Respiration
in cyanobacteria can occur in the thylakoid membrane alongside photosynthesis, with their photosynthetic
electron transport An electron transport chain (ETC) is a series of protein complexes and other molecules that electron transfer, transfer electrons from electron donors to electron acceptors via redox reactions (both Redox#Definitions, reduction and oxidation occu ...

electron transport
sharing the same compartment as the components of respiratory electron transport. While the goal of photosynthesis is to store energy by building carbohydrates from CO2, respiration is the reverse of this, with carbohydrates turned back into CO2 accompanying energy release. Cyanobacteria appear to separate these two processes with their plasma membrane containing only components of the respiratory chain, while the thylakoid membrane hosts an interlinked respiratory and photosynthetic electron transport chain. Cyanobacteria use electrons from
succinate dehydrogenase Succinate dehydrogenase (SDH) or succinate-coenzyme Q reductase (SQR) or respiratory complex II is an enzyme Enzymes () are proteins that act as biological catalysts (biocatalysts). Catalysts accelerate chemical reactions. The molecules up ...

succinate dehydrogenase
rather than from
NADPH Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle The Calvin cycle, light-independent reactions, bio syn ...
for respiration. Cyanobacteria only respire during the night (or in the dark) because the facilities used for electron transport are used in reverse for photosynthesis while in the light.


Electron transport chain

Many cyanobacteria are able to reduce nitrogen and carbon dioxide under
aerobic Aerobic means "requiring Earth's atmosphere, air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Cellular respiration#Aerobic r ...
conditions, a fact that may be responsible for their evolutionary and ecological success. The water-oxidizing photosynthesis is accomplished by coupling the activity of
photosystem Photosystems are functional and structural units of protein complex A protein complex or multiprotein complex is a group of two or more associated polypeptide chain Peptides (from Greek language Greek (modern , romanized: ''Elliniká'', A ...
(PS) II and I (). In contrast to
green sulfur bacteria The green sulfur bacteria (Chlorobiaceae) are a family In , family (from la, familia) is a of people related either by (by recognized birth) or (by marriage or other relationship). The purpose of families is to maintain the well-being ...
which only use one photosystem, the use of water as an electron donor is energetically demanding, requiring two photosystems. Attached to the thylakoid membrane, phycobilisomes act as light-harvesting antennae for the photosystems. The phycobilisome components (
phycobiliprotein Phycobiliproteins are water-soluble protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery ...
s) are responsible for the blue-green pigmentation of most cyanobacteria. The variations on this theme are due mainly to
carotenoid Carotenoids (), also called tetraterpenoids, are yellow, orange, and red organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ (anatomy), organ Chemistry * Organ ...
s and
phycoerythrin Phycoerythrin (PE) is a red protein-pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compoun ...
s that give the cells their red-brownish coloration. In some cyanobacteria, the color of light influences the composition of the phycobilisomes. In green light, the cells accumulate more phycoerythrin, whereas in red light they produce more
phycocyanin Phycocyanobilin Phycocyanin is a pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compound ...
. Thus, the bacteria appear green in red light and red in green light. This process of complementary chromatic adaptation is a way for the cells to maximize the use of available light for photosynthesis. A few genera lack phycobilisomes and have
chlorophyll b } Chlorophyll ''b'' is a form of chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in the mesosomes of cyanobacteria and in the chloroplast Chloroplasts are organelles that conduct photosynthesi ...

chlorophyll b
instead (''
Prochloron ''Prochloron'' (from the Greek ''pro'' (before) and the Greek ''chloros'' (green) ) is a unicellular oxygenic photosynthetic prokaryote commonly found as an extracellular symbiont on coral reefs, particularly in didemnid Ascidiacea, ascidians (sea ...
'', ''
Prochlorococcus ''Prochlorococcus'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also ref ...
'', ''Prochlorothrix''). These were originally grouped together as the prochlorophytes or chloroxybacteria, but appear to have developed in several different lines of cyanobacteria. For this reason, they are now considered as part of the cyanobacterial group.


Metabolism

In general, photosynthesis in cyanobacteria uses water as an
electron donor An electron donor is a chemical entity that donates electron The electron is a subatomic particle (denoted by the symbol or ) whose electric charge is negative one elementary charge. Electrons belong to the first generation (particle physics ...

electron donor
and produces
oxygen Oxygen is the chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have the same ...

oxygen
as a byproduct, though some may also use
hydrogen sulfide Hydrogen sulfide is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by havi ...

hydrogen sulfide
a process which occurs among other photosynthetic bacteria such as the
purple sulfur bacteria The purple sulfur bacteria (PSB) are part of a group of Proteobacteria Proteobacteria is a major phylum of Gram-negative bacteria. They include a wide variety of pathogenic genera, such as ''Escherichia'', ''Salmonella'', ''Vibrio'', ''Helicoba ...
.
Carbon dioxide Carbon dioxide (chemical formula A chemical formula is a way of presenting information about the chemical proportions of s that constitute a particular or molecule, using symbols, numbers, and sometimes also other symbols, such as pare ...

Carbon dioxide
is reduced to form
carbohydrate A carbohydrate () is a biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, for which they received a ...
s via the
Calvin cycle The Calvin cycle, light-independent reactions, bio synthetic phase, dark reactions, or photosynthetic carbon reduction (PCR) cycle of photosynthesis Photosynthesis is a process used by plants and other organisms to into that, through , can ...

Calvin cycle
. The large amounts of oxygen in the atmosphere are considered to have been first created by the activities of ancient cyanobacteria. They are often found as
symbiont Symbiosis (from Ancient Greek, Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different Organism, biological organisms, be it Mutualism (biology ...
s with a number of other groups of organisms such as fungi (lichens),
coral Corals are marine invertebrates Marine invertebrates are the invertebrates that live in marine habitats. Invertebrate is a blanket term that includes all animals apart from the vertebrate members of the chordate phylum. Invertebrates lack a ver ...

coral
s,
pteridophyte A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as "cryptogams", meaning that their means of reproduction is hidden. Ferns, h ...
s (''
Azolla ''Azolla'' (mosquito fern, duckweed fern, fairy moss, water fern) is a genus Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank In biological classification In biology, taxonomy () is the scientific study of ...

Azolla
''),
angiosperm Flowering plants include multiple members of the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greec ...

angiosperm
s (''
Gunnera ''Gunnera'' is the sole genus of herbaceous flowering plants in the family Gunneraceae, which contains 63 species. Some species have extremely large leaves. Species in the genus are variously native to Latin America, Australia, New Zealand, Pa ...
''), etc. There are some groups capable of
heterotrophic A heterotroph (; from Ancient Greek "other" and "nutrition") is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are prim ...
growth, while others are
parasitic Parasitism is a Symbiosis, symbiotic biological interactions, relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), ad ...
, causing diseases in invertebrates or algae (e.g., the
black band disease Black band disease is a coral disease in which corals develop a black band. It is characterized by complete tissue degradation due to a pathogenic microbial consortium. The mat is present between apparently healthy coral tissue and freshly expos ...
).


Ecology

Cyanobacteria can be found in almost every terrestrial and aquatic habitat –
ocean The ocean (also the sea The sea, connected as the world ocean or simply the ocean The ocean (also the sea or the world ocean) is the body of salt water which covers approximately 71% of the surface of the Earth.
s,
fresh water Fresh water or freshwater is any naturally occurring liquid or frozen water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in ...

fresh water
, damp soil, temporarily moistened rocks in
desert A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of ...

desert
s, bare rock and soil, and even
Antarctic The Antarctic (US English or , UK English or and or ) is a around 's , opposite the region around the . The Antarctic comprises the continent of , the and other located on the or south of the . The Antarctic region includes the , wa ...

Antarctic
rocks. They can occur as
planktonic Plankton are the diverse collection of organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology ...
cells or form phototrophic biofilms. They are found inside stones and shells (in endolithic ecosystems). A few are
endosymbiont An endosymbiont or endobiont is any organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, mol ...
s in
lichen A lichen ( , ) is a composite organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecu ...

lichen
s, plants, various
protist A protist () is any eukaryotic Eukaryotes () are organism In biology, an organism () is any organic, life, living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are c ...
s, or
sponges Sponges, the members of the phylum In biology, a phylum (; plural The plural (sometimes list of glossing abbreviations, abbreviated ), in many languages, is one of the values of the grammatical number, grammatical category of number. T ...

sponges
and provide energy for the
host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places *Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman *Michel Host (19 ...
. Some live in the fur of
sloth Sloths are a group of arboreal Neotropical xenarthran mammals, constituting the suborder Folivora. Noted for their slowness of movement, they spend most of their lives hanging upside down in the trees of the tropical rainforest File:Kop ...

sloth
s, providing a form of
camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard The leopard (''Pan ...

camouflage
. Aquatic cyanobacteria are known for their extensive and highly visible blooms that can form in both
freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water Water (chemical formula H2O) is an , transparent, tasteless, odorless, and , which is the main constituent of 's and the s of all known living organisms (in ...
and marine environments. The blooms can have the appearance of blue-green paint or scum. These blooms can be
toxic Toxicity is the degree to which a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects t ...

toxic
, and frequently lead to the closure of recreational waters when spotted. Marine bacteriophages are significant
parasites Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), adapted structurally to this w ...
of unicellular marine cyanobacteria. Cyanobacterial growth is favoured in ponds and lakes where waters are calm and have little turbulent mixing. Their lifecycles are disrupted when the water naturally or artificially mixes from churning currents caused by the flowing water of streams or the churning water of fountains. For this reason blooms of cyanobacteria seldom occur in rivers unless the water is flowing slowly. Growth is also favoured at higher temperatures which enable ''
Microcystis ''Microcystis'' is a genus of freshwater cyanobacteria that includes the harmful algal bloom-forming ''Microcystis aeruginosa''. Many members of a ''Microcystis'' community can produce neurotoxins and hepatotoxins, such as microcystin and cyanope ...
'' species to outcompete
diatoms Diatoms (''diá-tom-os'' 'cut in half', from ''diá'', 'through' or 'apart', and the root of ''tém-n-ō'', 'I cut') are a major group of algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic ...

diatoms
and
green algae The green algae (singular: green alga) are a large, informal grouping of algae consisting of the Chlorophyta and Charophyta/Streptophyta, which are now placed in separate Division (botany), divisions, together with the more basal Mesostigmatoph ...

green algae
, and potentially allow development of toxins. Based on environmental trends, models and observations suggest cyanobacteria will likely increase their dominance in aquatic environments. This can lead to serious consequences, particularly the contamination of sources of
drinking water Drinking water, also known as potable water, is water that is safe to drinking, drink or use for food preparation. The amount of drinking water required to maintain good health varies, and depends on physical activity level, age, health-related ...

drinking water
. Researchers including Linda Lawton at
Robert Gordon University , mottoeng = Now by all your mastered arts , established = 1992 (origins mid-18th century) , type = Public In public relations Public relations (PR) is the practice of managing and disseminating information from an individual or a ...
, have developed techniques to study these. Cyanobacteria can interfere with
water treatment Water treatment is any process that improves the quality Quality may refer to: Concepts *Quality (business), the ''non-inferiority'' or ''superiority'' of something *Quality (philosophy), an attribute or a property *Quality (physics), in respo ...

water treatment
in various ways, primarily by plugging filters (often large beds of sand and similar media) and by producing
cyanotoxin Cyanotoxins are toxin A toxin is a harmful substance produced within living cells or organisms; synthetic toxicants created by artificial processes are thus excluded. The term was first used by organic chemist Ludwig Brieger (1849–1919), der ...
s, which have the potential to cause serious illness if consumed. Consequences may also lie within fisheries and waste management practices. Anthropogenic
eutrophication Eutrophication (from Greek ''eutrophos'', "well-nourished") is the process by which an entire body of water (Lysefjord) in Norway Norway, officially the Kingdom of Norway,Names in the official and recognised languages: Bokmål Bokm ...

eutrophication
, rising temperatures, vertical stratification and increased
atmospheric carbon dioxide Carbon dioxide Carbon dioxide (chemical formula ) is a colorless gas with a density about 53% higher than that of dry air. Carbon dioxide molecules consist of a carbon atom covalent bond, covalently double bonded to two oxygen atoms. It occu ...
are contributors to cyanobacteria increasing dominance of aquatic ecosystems. Cyanobacteria have been found to play an important role in terrestrial habitats. It has been widely reported that cyanobacteria
soil crustSoil crusts are soil Soil (often stylized as SOiL) is an American rock band that was formed in Chicago (''City in a Garden''); I Will , image_map = , map_caption = Interactive maps of Chicago , coordinates ...
s help to stabilize soil to prevent
erosion In earth science Earth science or geoscience includes all fields of natural science Natural science is a branch of science Science (from the Latin word ''scientia'', meaning "knowledge") is a systematic enterprise that Scientific ...

erosion
and retain water. An example of a cyanobacterial species that does so is ''Microcoleus vaginatus''. ''M. vaginatus'' stabilizes soil using a
polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrate A carbohydrate () is a biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallograp ...
sheath that binds to sand particles and absorbs water. Some of these organisms contribute significantly to global ecology and the
oxygen cycle Oxygen cycle refers to the movement of oxygen through the atmosphere (air), Biosphere (plants and animals) and the Lithosphere (the earth’s crust). The oxygen cycle demonstrates how free oxygen is made available in each of these regions, as wel ...

oxygen cycle
. The tiny marine cyanobacterium ''
Prochlorococcus ''Prochlorococcus'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also ref ...
'' was discovered in 1986 and accounts for more than half of the photosynthesis of the open ocean.
Circadian rhythm A circadian rhythm (), or circadian cycle, is a natural, internal process that regulates the sleep–wake cycle and repeats roughly every 24 hours. It can refer to any process that originates within an organism (i.e., endogenous Endogenous subst ...

Circadian rhythm
s were once thought to only exist in eukaryotic cells but many cyanobacteria display a bacterial circadian rhythm.
"Cyanobacteria are arguably the most successful group of
microorganisms A microorganism, or microbe,, ''mikros'', "small") and ''organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes ...

microorganisms
on earth. They are the most genetically diverse; they occupy a broad range of habitats across all latitudes, widespread in freshwater, marine, and terrestrial ecosystems, and they are found in the most extreme niches such as hot springs, salt works, and hypersaline bays.
PhotoautotrophicPhotoautotrophs are organisms that use light energy Light or visible light is electromagnetic radiation In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis' ...
, oxygen-producing cyanobacteria created the conditions in the planet's early atmosphere that directed the evolution of aerobic metabolism and eukaryotic photosynthesis. Cyanobacteria fulfill vital ecological functions in the world's oceans, being important contributors to global carbon and nitrogen budgets." – Stewart and Falconer


Cyanobionts

Some cyanobacteria, the so-called
cyanobiont Cyanobionts are cyanobacteria that live in symbiosis with a wide range of organisms such as terrestrial plant, terrestrial or aquatic plant, aquatic plants; as well as, algal and fungal species. They can reside within extracellular or intracellular ...
s (cyanobacterial symbionts), have a
symbiotic Symbiosis (from Ancient Greek, Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different Organism, biological organisms, be it Mutualism (biolog ...
relationship with other organisms, both unicellular and multicellular. As illustrated on the right, there are many examples of cyanobacteria interacting symbiotically with
land plant The Embryophyta (), or land plants, are the most familiar group of green plant Plants are predominantly photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that w ...
s. Cyanobacteria can enter the plant through the
stomata In botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the ...

stomata
and colonize the intercellular space, forming loops and intracellular coils. ''
Anabaena ''Anabaena'' is a genus of Filamentation, filamentous cyanobacteria that exist as plankton. They are known for nitrogen-fixing abilities, and they form symbiosis, symbiotic relationships with certain plants, such as the mosquito fern. They are one ...
'' spp. colonize the roots of wheat and cotton plants. ''
Calothrix ''Calothrix'' is a genus of cyanobacteria. They are generally found in freshwater. References

Rivulariaceae Cyanobacteria genera {{cyanobacteria-stub ...
'' sp. has also been found on the root system of wheat.
Monocot Monocotyledons (), commonly referred to as monocots, (Lilianae Lilianae (also known as Liliiflorae) is a botanical name for a superorder (that is, a rank (botany), rank higher than that of order (biology), order) of flowering plants. Such a supe ...
s, such as wheat and rice, have been colonised by ''
Nostoc ''Nostoc'', also known as star jelly Star jelly (also called astromyxin, astral jelly) is a gelatinous substance sometimes found on grass or even on branches of trees. According to folklore, it is deposited on the Earth during meteor showers. St ...

Nostoc
'' spp., In 1991, Ganther and others isolated diverse heterocystous nitrogen-fixing cyanobacteria, including ''Nostoc'', ''Anabaena'' and ''
Cylindrospermum ''Cylindrospermum'' is a genus of filamentous cyanobacteria Cyanobacteria , also known as Cyanophyta, are a phylum of Gram-negative bacteria Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram ...
'', from plant root and soil. Assessment of wheat seedling roots revealed two types of association patterns: loose colonization of root hair by ''Anabaena'' and tight colonization of the root surface within a restricted zone by ''Nostoc''. The relationships between
cyanobiont Cyanobionts are cyanobacteria that live in symbiosis with a wide range of organisms such as terrestrial plant, terrestrial or aquatic plant, aquatic plants; as well as, algal and fungal species. They can reside within extracellular or intracellular ...
s (cyanobacterial symbionts) and protistan hosts are particularly noteworthy, as some nitrogen-fixing cyanobacteria (diazotrophs) play an important role in Marine primary production, primary production, especially in nitrogen-limited oligotrophic oceans. Cyanobacteria, mostly pico-sized ''
Synechococcus ''Synechococcus'' (from the Greek ''synechos'', in succession, and the Greek ''kokkos'', granule) is a unicellular cyanobacterium Cyanobacteria , also known as Cyanophyta, are a phylum In biology, a phylum (; plural The plural (somet ...
'' and ''
Prochlorococcus ''Prochlorococcus'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also ref ...
'', are ubiquitously distributed and are the most abundant photosynthetic organisms on Earth, accounting for a quarter of all carbon fixed in marine ecosystems. In contrast to free-living marine cyanobacteria, some cyanobionts are known to be responsible for nitrogen fixation rather than carbon fixation in the host. However, the physiological functions of most cyanobionts remain unknown. Cyanobionts have been found in numerous protist groups, including dinoflagellates, tintinnids, radiolarians, amoebae,
diatom Diatoms (''diá-tom-os'' 'cut in half', from ''diá'', 'through' or 'apart', and the root of ''tém-n-ō'', 'I cut') are a major group of algae Algae (; singular alga ) is an informal term for a large and diverse group of s. It is a grou ...

diatom
s, and haptophytes. Among these cyanobionts, little is known regarding the nature (e.g., genetic diversity, host or cyanobiont specificity, and cyanobiont seasonality) of the symbiosis involved, particularly in relation to dinoflagellate host.


Collective behaviour

Some cyanobacteria – even single-celled ones – show striking collective behaviours and form colonies (or algal bloom, blooms) that can float on water and have important ecological roles. For instance, billions of years ago, communities of marine Paleoproterozoic cyanobacteria could have helped create the biosphere as we know it by burying carbon compounds and allowing the initial build-up of oxygen in the atmosphere. On the other hand, Harmful algal bloom, toxic cyanobacterial blooms are an increasingly issue for society, as their toxins can be harmful to animals. Extreme blooms can also deplete water of oxygen and reduce the penetration of sunlight and visibility, thereby compromising the feeding and mating behaviour of light-reliant species. As shown in the diagram on the right, bacteria can stay in suspension as individual cells, adhere collectively to surfaces to form biofilms, passively sediment, or flocculate to form suspended aggregates. Cyanobacteria are able to produce sulphated
polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrate A carbohydrate () is a biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallograp ...
s (yellow haze surrounding clumps of cells) that enable them to form floating aggregates. In 2021, Maeda et al. discovered that oxygen produced by cyanobacteria becomes trapped in the network of polysaccharides and cells, enabling the microorganisms to form buoyant blooms. It is thought that specific protein fibres known as Pilus, pili (represented as lines radiating from the cells) may act as an additional way to link cells to each other or onto surfaces. Some cyanobacteria also use sophisticated intracellular
gas vesicle Gas vesicles, also known as gas vacuoles, are nanocompartments in certain prokaryotic organisms, which help in buoyancy. Gas vesicles are composed entirely of protein Proteins are large biomolecules or macromolecules that are comprised of one ...
s as floatation aids. The diagram on the left above shows a proposed model of microbial distribution, spatial organization, carbon and O2 cycling in clumps and adjacent areas. (a) Clumps contain denser cyanobacterial filaments and heterotrophic microbes. The initial differences in density depend on cyanobacterial motility and can be established over short timescales. Darker blue color outside of the clump indicates higher oxygen concentrations in areas adjacent to clumps. Oxic media increase the reversal frequencies of any filaments that begin to leave the clumps, thereby reducing the net migration away from the clump. This enables the persistence of the initial clumps over short timescales; (b) Spatial coupling between photosynthesis and respiration in clumps. Oxygen produced by cyanobacteria diffuses into the overlying medium or is used for aerobic respiration. Dissolved inorganic carbon (DIC) diffuses into the clump from the overlying medium and is also produced within the clump by respiration. In oxic solutions, high O2 concentrations reduce the efficiency of CO2 fixation and result in the excretion of glycolate. Under these conditions, clumping can be beneficial to cyanobacteria if it stimulates the retention of carbon and the assimilation of inorganic carbon by cyanobacteria within clumps. This effect appears to promote the accumulation of particulate organic carbon (cells, sheaths and heterotrophic organisms) in clumps. It has been unclear why and how cyanobacteria form communities. Aggregation must divert resources away from the core business of making more cyanobacteria, as it generally involves the production of copious quantities of extracellular material. In addition, cells in the centre of dense aggregates can also suffer from both shading and shortage of nutrients. So, what advantage does this communal life bring for cyanobacteria? New insights into how cyanobacteria form blooms have come from a 2021 study on the cyanobacterium ''
Synechocystis ''Synechocystis'' is a genus of unicellular, freshwater cyanobacteria Cyanobacteria , also known as Cyanophyta, are a phylum of Gram-negative bacteria Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in ...

Synechocystis
''. These use a set of genes that regulate the production and export of sulphated
polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrate A carbohydrate () is a biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallograp ...
s, chains of sugar molecules modified with sulphate groups that can often be found in marine algae and animal tissue. Many bacteria generate extracellular polysaccharides, but sulphated ones have only been seen in cyanobacteria. In ''Synechocystis'' these sulphated polysaccharide help the cyanobacterium form buoyant aggregates by trapping oxygen bubbles in the slimy web of cells and polysaccharides. Previous studies on ''Synechocystis'' have shown type IV pili, which decorate the surface of cyanobacteria, also play a role in forming blooms. These retractable and adhesive protein fibres are important for motility, adhesion to substrates and DNA uptake. The formation of blooms may require both type IV pili and Synechan – for example, the pili may help to export the polysaccharide outside the cell. Indeed, the activity of these protein fibres may be connected to the production of extracellular polysaccharides in filamentous cyanobacteria. A more obvious answer would be that pili help to build the aggregates by binding the cells with each other or with the extracellular polysaccharide. As with other kinds of bacteria, certain components of the pili may allow cyanobacteria from the same species to recognise each other and make initial contacts, which are then stabilised by building a mass of extracellular polysaccharide. The bubble flotation mechanism identified by Maeda et al. joins a range of known strategies that enable cyanobacteria to control their buoyancy, such as using gas vesicles or accumulating carbohydrate ballasts. Type IV pili on their own could also control the position of marine cyanobacteria in the water column by regulating viscous drag. Extracellular polysaccharide appears to be a multipurpose asset for cyanobacteria, from floatation device to food storage, defence mechanism and mobility aid.


Cellular death

One of the most critical processes determining cyanobacterial eco-physiology is cellular death. Evidence supports the existence of controlled cellular demise in cyanobacteria, and various forms of cell death have been described as a response to biotic and abiotic stresses. However, cell death research in cyanobacteria is a relatively young field and understanding of the underlying mechanisms and molecular machinery underpinning this fundamental process remains largely elusive. However, reports on cell death of marine and freshwater cyanobacteria indicate this process has major implications for the ecology of microbial communities/Agustí, S. (2004)
"Viability and niche segregation of ''Prochlorococcus'' and ''Synechococcus'' cells across the Central Atlantic Ocean."
Accessed: 30 July 2021).
Different forms of cell demise have been observed in cyanobacteria under several stressful conditions, and cell death has been suggested to play a key role in developmental processes, such as akinete and heterocyst differentiation.


Cyanophages

File:Cyanophages.png, Electron micrograph of a negative-stained ''
Prochlorococcus ''Prochlorococcus'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also ref ...
'' myoviruses File:Structure of a Myoviridae bacteriophage 2.jpg, Typical structure of a myovirus
Cyanophages are viruses that infect cyanobacteria. Cyanophages can be found in both freshwater and marine environments. Marine and freshwater cyanophages have Regular icosahedron, icosahedral heads, which contain double-stranded DNA, attached to a tail by connector proteins. The size of the head and tail vary among species of cyanophages. Cyanophages like other bacteriophages rely on Brownian motion to collide with bacteria, and then use receptor binding proteins to recognize cell surface proteins, which leads to adherence. Viruses with contractile tails then rely on receptors found on their tails to recognize highly conserved proteins on the surface of the host cell. Cyanophages infect a wide range of cyanobacteria and are key regulators of the cyanobacterial populations in aquatic environments, and may aid in the prevention of cyanobacterial blooms in freshwater and marine ecosystems. These blooms can pose a danger to humans and other animals, particularly in eutrophic freshwater lakes. Infection by these viruses is highly prevalent in cells belonging to ''
Synechococcus ''Synechococcus'' (from the Greek ''synechos'', in succession, and the Greek ''kokkos'', granule) is a unicellular cyanobacterium Cyanobacteria , also known as Cyanophyta, are a phylum In biology, a phylum (; plural The plural (somet ...
'' spp. in marine environments, where up to 5% of cells belonging to marine cyanobacterial cells have been reported to contain mature phage particles. The first cyanophage, Cyanophage LPP-1, LPP-1, was discovered in 1963. Cyanophages are classified within the bacteriophage families ''Myoviridae'' (e.g. cyanophage AS-1, AS-1, cyanophage N-1, N-1), ''Podoviridae'' (e.g. LPP-1) and ''Siphoviridae'' (e.g. cyanophage S-1, S-1).Sarma TA. 'Cyanophages' in ''Handbook of Cyanobacteria'' (CRC Press; 2012) ()


Movement

It has long been known that filamentous cyanobacteria perform surface motions, and that these movements result from type IV pili. Additionally, ''
Synechococcus ''Synechococcus'' (from the Greek ''synechos'', in succession, and the Greek ''kokkos'', granule) is a unicellular cyanobacterium Cyanobacteria , also known as Cyanophyta, are a phylum In biology, a phylum (; plural The plural (somet ...
'', a marine cyanobacteria, is known to swim at a speed of 25 μm/s by a mechanism different to that of bacterial flagella. Formation of waves on the cyanobacteria surface is thought to push surrounding water backwards. Material was copied from this source, which is available under
Creative Commons Attribution 4.0 International License
Cells are known to be motile by a gliding method and a novel uncharacterized, nonphototactic swimming method that does not involve flagellar motion. Many species of cyanobacteria are capable of gliding. Gliding motility, Gliding is a form of cell movement that differs from crawling or swimming in that it does not rely on any obvious external organ or change in cell shape and it occurs only in the presence of a substrate (biology), substrate. Gliding in filamentous cyanobacteria appears to be powered by a "slime jet" mechanism, in which the cells extrude a gel that expands quickly as it hydrates providing a propulsion force, although some
unicellular A unicellular organism, also known as a single-celled organism, is an organism In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemica ...
cyanobacteria use type IV pili for gliding. Cyanobacteria have strict light requirements. Too little light can result in insufficient energy production, and in some species may cause the cells to resort to heterotrophic respiration. Too much light can inhibit the cells, decrease photosynthesis efficiency and cause damage by bleaching. UV radiation is especially deadly for cyanobacteria, with normal solar levels being significantly detrimental for these microorganisms in some cases. Filamentous cyanobacteria that live in microbial mats often migrate vertically and horizontally within the mat in order to find an optimal niche that balances their light requirements for photosynthesis against their sensitivity to photodamage. For example, the filamentous cyanobacteria ''
Oscillatoria ''Oscillatoria'' is a genus of filamentous The word filament, which is descended from Latin ''filum'' meaning "Thread (yarn), thread", is used in English for a variety of thread-like structures, including: In commerce * Fiber or, more loosely ...

Oscillatoria
'' sp. and ''Spirulina (genus), Spirulina subsalsa'' found in the hypersaline benthic mats of Guerrero Negro, Mexico migrate downwards into the lower layers during the day in order to escape the intense sunlight and then rise to the surface at dusk. In contrast, the population of ''Microcoleus, Microcoleus chthonoplastes'' found in hypersaline mats in Camargue, France migrate to the upper layer of the mat during the day and are spread homogenously through the mat at night. An in vitro experiment using P. uncinatum also demonstrated this species' tendency to migrate in order to avoid damaging radiation. These migrations are usually the result of some sort of photomovement, although other forms of taxis can also play a role. Photomovement – the modulation of cell movement as a function of the incident light – is employed by the cyanoabacteria as a means to find optimal light conditions in their environment. There are three types of photomovement: photokinesis, phototaxis and photophobic responses. Photokinetic microorganisms modulate their gliding speed according to the incident light intensity. For example, the speed with which Phormidium autumnale glides increases linearly with the incident light intensity. Phototactic microorganisms move according to the direction of the light within the environment, such that positively phototactic species will tend to move roughly parallel to the light and towards the light source. Species such as ''Phormidium, Phormidium uncinatum'' cannot steer directly towards the light, but rely on random collisions to orient themselves in the right direction, after which they tend to move more towards the light source. Others, such as ''Anabaena variabilis'', can steer by bending the trichome. Finally, photophobic microorganisms respond to spatial and temporal light gradients. A step-up photophobic reaction occurs when an organism enters a brighter area field from a darker one and then reverses direction, thus avoiding the bright light. The opposite reaction, called a step-down reaction, occurs when an organism enters a dark area from a bright area and then reverses direction, thus remaining in the light.


Evolution


Earth history

Stromatolites are layered biochemical accretion (geology), accretionary structures formed in shallow water by the trapping, binding, and cementation of sedimentary grains by biofilms (
microbial mat The cyanobacterial algal mat, salty lake on the White Sea">algal_mat.html" ;"title="cyanobacterial algal mat">cyanobacterial algal mat, salty lake on the White Sea seaside A microbial mat is a multi-layered sheet of microorganisms, mainly bacteria ...
s) of microorganisms, especially cyanobacteria. During the Precambrian, stromatolite communities of microorganisms grew in most marine and non-marine environments in the photic zone. After the Cambrian explosion of marine animals, grazing on the stromatolite mats by herbivores greatly reduced the occurrence of the stromatolites in marine environments. Since then, they are found mostly in hypersaline conditions where grazing invertebrates cannot live (e.g. Shark Bay, Western Australia). Stromatolites provide ancient records of life on Earth by fossil remains which date from 3.5 annus#SI prefix multipliers, Ga ago. the oldest undisputed evidence of cyanobacteria is from 2.1 Ga ago, but there is some evidence for them as far back as 2.7 Ga ago., Oxygen concentrations in the atmosphere remained around or below 1% of today's level until 2.4 Ga ago (the
Great Oxygenation Event The Great Oxidation Event (GOE), also called the Great Oxygenation Event, the Oxygen catastrophe, and the Oxygen Crisis, was a time interval when the Earth's atmosphere The atmosphere of Earth is the layer of gas Gas is one of the ...
). The rise in oxygen may have caused a fall in the concentration of atmospheric methane, and triggered the Huronian glaciation from around 2.4 to 2.1 Ga ago. In this way, cyanobacteria may have killed off much of the other bacteria of the time.Nick Lane, Lane, Nick (6 February 2010
"First breath: Earth's billion-year struggle for oxygen"
''New Scientist'', pp. 36–39. See accompanying graph as well.
Oncolites are sedimentary structures composed of oncoids, which are layered structures formed by cyanobacterial growth. Oncolites are similar to stromatolites, but instead of forming columns, they form approximately spherical structures that were not attached to the underlying substrate as they formed. The oncoids often form around a central nucleus, such as a shell fragment, and a calcium carbonate structure is deposited by encrusting microbes. Oncolites are indicators of warm waters in the photic zone, but are also known in contemporary freshwater environments. These structures rarely exceed 10 cm in diameter. One former classification scheme of cyanobacterial fossils divided them into the porostromata and the spongiostromata. These are now recognized as form taxa and considered taxonomically obsolete; however, some authors have advocated for the terms remaining informally to describe form and structure of bacterial fossils. File:Stromatolites.jpg, Stromatolites left behind by cyanobacteria are the oldest known fossils of life on Earth. This fossil is one billion years old. File:Oncolitic limestone (central Utah, USA) 3.jpg, Oncolitic limestone formed from successive layers of calcium carbonate precipitated by cyanobacteria File:Oscillatoriopsis longa fossil.jpg,


Origin of photosynthesis

As far as we can tell, oxygenic photosynthesis only evolved once (in prokaryotic cyanobacteria), and all photosynthetic eukaryotes (including all plants and algae) have acquired this ability from them. In other words, all the oxygen that makes the atmosphere breathable for aerobic organisms originally comes from cyanobacteria or their later descendants. Cyanobacteria remained principal primary producers throughout the Proterozoic Eon (2500–543 Ma), in part because the redox structure of the oceans favored photoautotrophs capable of
nitrogen fixation Nitrogen fixation is a chemical process by which molecular nitrogen Nitrogen is the chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific st ...
. Green algae joined blue-greens as major primary producers on Continental shelf, continental shelves near the end of the Proterozoic, but only with the Mesozoic (251–65 Ma) radiations of dinoflagellates, coccolithophorids, and diatoms did primary production in marine shelf waters take modern form. Cyanobacteria remain critical to marine ecosystems as primary producers in oceanic gyres, as agents of biological nitrogen fixation, and, in modified form, as the
plastid The plastid (Greek: πλαστός; plastós: formed, molded – plural plastids) is a membrane-bound organelle In cell biology, an organelle is a specialized subunit, usually within a cell (biology), cell, that has a specific function. The name ' ...
s of marine algae.


Origin of chloroplasts

Primary chloroplasts are cell organelles found in some Eukarya, eukaryotic lineages, where they are specialized in performing photosynthesis. They are considered to have evolved from
endosymbiotic An endosymbiont or endobiont is any organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any individual contiguous system that embodies the Life#Biology, properties of life. It is a synony ...
cyanobacteria. After some years of debate, it is now generally accepted that the three major groups of primary endosymbiotic eukaryotes (i.e. Viridiplantae, green plants, Rhodophytes, red algae and glaucophytes) form one large Monophyly, monophyletic group called Archaeplastida, which evolved after one unique endosymbiotic event. The Morphology (biology), morphological similarity between chloroplasts and cyanobacteria was first reported by German botanist Andreas Franz Wilhelm Schimper in the 19th century Chloroplasts are only found in plants and
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic Photosynthesis is a process used by plants and other organisms to convert Conversion or convert may refer to: Arts, entertainment, and media * Co ...

algae
, thus paving the way for Russian biologist Konstantin Mereschkowski to suggest in 1905 the symbiogenic origin of the plastid. Lynn Margulis brought this hypothesis back to attention more than 60 years later but the idea did not become fully accepted until supplementary data started to accumulate. The cyanobacterial origin of plastids is now supported by various pieces of Phylogenetics, phylogenetic, Genomics, genomic, biochemical and structural evidence. The description of another independent and more recent primary endosymbiosis event between a cyanobacterium and a separate eukaryote lineage (the rhizarian ''Paulinella chromatophora'') also gives credibility to the endosymbiotic origin of the plastids. In addition to this primary endosymbiosis, many eukaryotic lineages have been subject to Secondary endosymbiosis, secondary or even tertiary endosymbiotic events, that is the "Matryoshka doll, Matryoshka-like" engulfment by a eukaryote of another plastid-bearing eukaryote. {{clear Chloroplasts have many similarities with cyanobacteria, including a circular chromosome, prokaryotic-type ribosomes, and similar proteins in the photosynthetic reaction center. The endosymbiotic theory suggests that photosynthetic bacteria were acquired (by endocytosis) by early Eukaryote, eukaryotic cells to form the first plant cells. Therefore, chloroplasts may be photosynthetic bacteria that adapted to life inside plant cells. Like mitochondrion, mitochondria, chloroplasts still possess their own DNA, separate from the nuclear DNA of their plant host cells and the genes in this chloroplast DNA resemble those in cyanobacteria. DNA in chloroplasts codes for redox proteins such as photosynthetic reaction centers. The CoRR hypothesis proposes this co-location is required for redox regulation.


Marine origins

{{plankton sidebar, taxonomy Cyanobacteria have fundamentally transformed the geochemistry of the planet.{{cite journal , doi = 10.1098/rstb.2006.1838, title = The oxygenation of the atmosphere and oceans, year = 2006, last1 = Holland, first1 = Heinrich D., journal = Philosophical Transactions of the Royal Society B: Biological Sciences, volume = 361, issue = 1470, pages = 903–915, pmid = 16754606, pmc = 1578726 Multiple lines of geochemical evidence support the occurrence of intervals of profound global environmental change at the beginning and end of the Proterozoic (2,500–542 Mya).{{cite journal , doi = 10.1126/science.1258410, title = Low Mid-Proterozoic atmospheric oxygen levels and the delayed rise of animals, year = 2014, last1 = Planavsky, first1 = N. J., last2 = Reinhard, first2 = C. T., last3 = Wang, first3 = X., last4 = Thomson, first4 = D., last5 = McGoldrick, first5 = P., last6 = Rainbird, first6 = R. H., last7 = Johnson, first7 = T., last8 = Fischer, first8 = W. W., last9 = Lyons, first9 = T. W., journal = Science, volume = 346, issue = 6209, pages = 635–638, pmid = 25359975, bibcode = 2014Sci...346..635P, s2cid = 37395258 {{cite journal , doi = 10.1038/nature13068, title = The rise of oxygen in Earth's early ocean and atmosphere, year = 2014, last1 = Lyons, first1 = Timothy W., last2 = Reinhard, first2 = Christopher T., last3 = Planavsky, first3 = Noah J., journal = Nature, volume = 506, issue = 7488, pages = 307–315, pmid = 24553238, bibcode = 2014Natur.506..307L, s2cid = 4443958{{cite journal , doi = 10.1038/nature11445, title = Ocean oxygenation in the wake of the Marinoan glaciation, year = 2012, last1 = Sahoo, first1 = Swapan K., last2 = Planavsky, first2 = Noah J., last3 = Kendall, first3 = Brian, last4 = Wang, first4 = Xinqiang, last5 = Shi, first5 = Xiaoying, last6 = Scott, first6 = Clint, last7 = Anbar, first7 = Ariel D., last8 = Lyons, first8 = Timothy W., last9 = Jiang, first9 = Ganqing, journal = Nature, volume = 489, issue = 7417, pages = 546–549, pmid = 23018964, bibcode = 2012Natur.489..546S, s2cid = 4391882 While it is widely accepted that the presence of molecular oxygen in the early fossil record was the result of cyanobacteria activity, little is known about how cyanobacteria evolution (e.g., habitat preference) may have contributed to changes in
biogeochemical cycle In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Topics of interest include the bi ...
s through Earth history. Geochemical evidence has indicated that there was a first step-increase in the oxygenation of the Earth's surface, which is known as the Great Oxidation Event (GOE), in the early Paleoproterozoic (2,500–1,600 Mya). A second but much steeper increase in oxygen levels, known as the Neoproterozoic Oxygenation Event (NOE),{{cite journal , doi = 10.1016/j.earscirev.2011.09.004, title = The Neoproterozoic oxygenation event: Environmental perturbations and biogeochemical cycling, year = 2012, last1 = Och, first1 = Lawrence M., last2 = Shields-Zhou, first2 = Graham A., journal = Earth-Science Reviews, volume = 110, issue = 1–4, pages = 26–57, bibcode = 2012ESRv..110...26O{{cite journal , doi = 10.1126/science.1135013, title = Late-Neoproterozoic Deep-Ocean Oxygenation and the Rise of Animal Life, year = 2007, last1 = Canfield, first1 = D. E., last2 = Poulton, first2 = S. W., last3 = Narbonne, first3 = G. M., journal = Science, volume = 315, issue = 5808, pages = 92–95, pmid = 17158290, bibcode = 2007Sci...315...92C, s2cid = 24761414 occurred at around 800 to 500 Mya.{{cite journal , doi = 10.1038/nature05345, title = Oxidation of the Ediacaran Ocean, year = 2006, last1 = Fike, first1 = D. A., last2 = Grotzinger, first2 = J. P., last3 = Pratt, first3 = L. M., last4 = Summons, first4 = R. E., journal = Nature, volume = 444, issue = 7120, pages = 744–747, pmid = 17151665, bibcode = 2006Natur.444..744F, s2cid = 4337003 Recent chromium isotope data point to low levels of atmospheric oxygen in the Earth's surface during the mid-Proterozoic, which is consistent with the late evolution of marine planktonic cyanobacteria during the Cryogenian;{{cite journal , doi = 10.1016/j.cub.2014.01.041, title = A Neoproterozoic Transition in the Marine Nitrogen Cycle, year = 2014, last1 = Sánchez-Baracaldo, first1 = Patricia, last2 = Ridgwell, first2 = Andy, last3 = Raven, first3 = John A., journal = Current Biology, volume = 24, issue = 6, pages = 652–657, pmid = 24583016, s2cid = 16756351, doi-access = free both types of evidence help explain the late emergence and diversification of animals.{{cite journal , doi = 10.1126/science.1206375, title = The Cambrian Conundrum: Early Divergence and Later Ecological Success in the Early History of Animals, year = 2011, last1 = Erwin, first1 = D. H., last2 = Laflamme, first2 = M., last3 = Tweedt, first3 = S. M., last4 = Sperling, first4 = E. A., last5 = Pisani, first5 = D., last6 = Peterson, first6 = K. J., journal = Science, volume = 334, issue = 6059, pages = 1091–1097, pmid = 22116879, bibcode = 2011Sci...334.1091E, s2cid = 7737847 Understanding the evolution of planktonic cyanobacteria is important because their origin fundamentally transformed the nitrogen cycle, nitrogen and carbon cycles towards the end of the Pre-Cambrian. It remains unclear, however, what evolutionary events led to the emergence of open-ocean planktonic forms within cyanobacteria and how these events relate to geochemical evidence during the Pre-Cambrian. So far, it seems that ocean geochemistry (e.g., euxinic conditions during the early- to mid-Proterozoic) and nutrient availability{{hsp likely contributed to the apparent delay in diversification and widespread colonization of open ocean environments by planktonic cyanobacteria during the Neoproterozoic.


Genetics

Cyanobacteria are capable of natural genetic transformation (genetics), transformation.{{cite journal , vauthors=Orkwiszewski KG, Kaney AR , s2cid=5635245 , title=Genetic transformation of the blue-green bacterium, Anacystis nidulans , journal=Arch Mikrobiol , volume=98 , issue=1 , pages=31–37 , date=June 1974 , pmid=4209657 , doi= 10.1007/BF00425265{{cite journal , vauthors=Stevens SE, Porter RD , title=Transformation in Agmenellum quadruplicatum , journal=Proc. Natl. Acad. Sci. U.S.A. , volume=77 , issue=10 , pages=6052–56 , date=October 1980 , pmid=16592896 , pmc=350211 , doi= 10.1073/pnas.77.10.6052, bibcode=1980PNAS...77.6052S Natural genetic transformation is the genetic alteration of a cell resulting from the direct uptake and incorporation of exogenous DNA from its surroundings. For bacterial transformation to take place, the recipient bacteria must be in a state of natural competence, competence, which may occur in nature as a response to conditions such as starvation, high cell density or exposure to DNA damaging agents. In chromosomal transformation, homologous transforming DNA can be integrated into the recipient genome by homologous recombination, and this process appears to be an adaptation for DNA repair, repairing DNA damage.{{cite journal , vauthors=Bernstein H, Bernstein C, Michod RE , title=Sex in microbial pathogens , journal=Infect. Genet. Evol. , volume=57 , pages=8–25 , date=January 2018 , pmid=29111273 , doi=10.1016/j.meegid.2017.10.024


DNA repair

Cyanobacteria are challenged by environmental stresses and internally generated reactive oxygen species that cause DNA damage (naturally occurring), DNA damage. Cyanobacteria possess numerous ''Escherichia coli, E. coli''-like DNA repair genes.{{cite journal , vauthors=Cassier-Chauvat C, Veaudor T, Chauvat F , title=Comparative Genomics of DNA Recombination and Repair in Cyanobacteria: Biotechnological Implications , journal=Front Microbiol , volume=7 , pages=1809 , date=2016 , pmid=27881980 , pmc=5101192 , doi=10.3389/fmicb.2016.01809 , doi-access=free Several DNA repair genes are highly conserved in cyanobacteria, even in small genomes, suggesting that core DNA repair processes such as homologous recombination, recombinational repair, nucleotide excision repair and methyl-directed DNA mismatch repair are common among cyanobacteria.


Classification

{{See also, Bacterial taxonomy Historically, bacteria were first classified as plants constituting the class Schizomycetes, which along with the Schizophyceae (blue-green algae/Cyanobacteria) formed the phylum Schizophyta,{{cite journal , vauthors = Von Nägeli C , veditors = Caspary R , year = 1857 , title = Bericht über die Verhandlungen der 33. Versammlung deutscher Naturforscher und Ärzte, gehalten in Bonn von 18 bis 24 September 1857 , trans-title = Report on the Proceedings of the 33rd Meeting of German Natural Scientists and Physicians, held in Bonn, 18 to 24 September 1857 , journal = Botanische Zeitung , volume = 15 , pages = 749–76 then in the phylum Monera in the kingdom Protista by Haeckel in 1866, comprising ''Protogens, Protamaeba, Vampyrella, Protomonae'', and ''Vibrio'', but not ''Nostoc'' and other cyanobacteria, which were classified with algae, later reclassified as the ''Prokaryotes'' by Édouard Chatton, Chatton. The cyanobacteria were traditionally classified by morphology into five sections, referred to by the numerals I–V. The first three – Chroococcales, Pleurocapsales, and Oscillatoriales – are not supported by phylogenetic studies. The latter two – Nostocales and Stigonematales – are monophyletic, and make up the heterocystous cyanobacteria.{{cite journal , vauthors = Gugger MF, Hoffmann L , title = Polyphyly of true branching cyanobacteria (Stigonematales) , journal = International Journal of Systematic and Evolutionary Microbiology , volume = 54 , issue = Pt 2 , pages = 349–57 , date = March 2004 , pmid = 15023942 , doi = 10.1099/ijs.0.02744-0 , doi-access = free The members of Chroococales are unicellular and usually aggregate in colonies. The classic taxonomic criterion has been the cell morphology and the plane of cell division. In Pleurocapsales, the cells have the ability to form internal spores (baeocytes). The rest of the sections include filamentous species. In Oscillatoriales, the cells are uniseriately arranged and do not form specialized cells (akinetes and heterocysts). In Nostocales and Stigonematales, the cells have the ability to develop heterocysts in certain conditions. Stigonematales, unlike Nostocales, include species with truly branched trichomes. Most taxa included in the phylum or division Cyanobacteria have not yet been validly published under ''The International Code of Nomenclature of Prokaryotes'' (ICNP) except: *The classes Chroobacteria, Hormogoneae, and Gloeobacteria *The orders Chroococcales, Gloeobacterales, Nostocales, Oscillatoriales, Pleurocapsales, and Stigonematales *The families Prochloraceae and Prochlorotrichaceae *The genera ''Halospirulina, Planktothricoides,
Prochlorococcus ''Prochlorococcus'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of things or concepts, including the principles that underlie such classification. The term may also ref ...
,
Prochloron ''Prochloron'' (from the Greek ''pro'' (before) and the Greek ''chloros'' (green) ) is a unicellular oxygenic photosynthetic prokaryote commonly found as an extracellular symbiont on coral reefs, particularly in didemnid Ascidiacea, ascidians (sea ...
'', and ''Prochlorothrix'' The remainder are validly published under the International Code of Nomenclature for algae, fungi, and plants. Formerly, some bacteria, like ''Beggiatoa'', were thought to be colorless Cyanobacteria.{{cite book, last=Pringsheim, first=Ernst Georg , name-list-style = vanc , title=Farblose Algen: Ein Beitrag zur Evolutionsforschung, url={{google books , plainurl=y , id=RYnPAAAAMAAJ, year=1963, publisher=Gustav Fischer Verlag


Relation to humans


Biotechnology

The unicellular cyanobacterium ''
Synechocystis ''Synechocystis'' is a genus of unicellular, freshwater cyanobacteria Cyanobacteria , also known as Cyanophyta, are a phylum of Gram-negative bacteria Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in ...

Synechocystis
'' sp. PCC6803 was the third prokaryote and first photosynthetic organism whose genome was completely DNA sequencing, sequenced. It continues to be an important model organism. '' Cyanothece'' ATCC 51142 is an important diazotrophic model organism. The smallest genomes have been found in ''Prochlorococcus'' spp. (1.7 Mb) and the largest in ''Nostoc punctiforme'' (9 Mb). Those of ''
Calothrix ''Calothrix'' is a genus of cyanobacteria. They are generally found in freshwater. References

Rivulariaceae Cyanobacteria genera {{cyanobacteria-stub ...
'' spp. are estimated at 12–15 Mb, as large as yeast. Recent research has suggested the potential application of cyanobacteria to the generation of renewable energy by directly converting sunlight into electricity. Internal photosynthetic pathways can be coupled to chemical mediators that transfer electrons to external electrodes. In the shorter term, efforts are underway to commercialize algae-based fuels such as diesel fuel, diesel, gasoline, and jet fuel. Cyanobacteria have been also engineered to produce ethanol and experiments have shown that when one or two CBB genes are being over expressed, the yield can be even higher Cyanobacteria may possess the ability to produce substances that could one day serve as anti-inflammatory agents and combat bacterial infections in humans. Cyanobacteria's photosynthetic output of sugar and oxygen has been demonstrated to have therapeutic value in rats with heart attacks. While cyanobacteria can naturally produce various secondary metabolites, they can serve as advantageous hosts for plant-derived metabolites production owing to biotechnological advances in systems biology and synthetic biology. Spirulina's extracted blue color is used as a natural food coloring. Researchers from several space agencies argue that cyanobacteria could be used for producing goods for human consumption in future manned outposts on Mars, by transforming materials available on this planet.{{cite journal , title = Sustainable life support on Mars – the potential roles of cyanobacteria, journal = International Journal of Astrobiology, date = 2016, last1 = Verseux, first1 = Cyprien, last2 = Baqué, first2 = Mickael, last3 = Lehto, first3 = Kirsi, last4 = de Vera, first4 = Jean-Pierre P., last5 = Rothschild, first5 = Lynn J., last6 = Billi, first6 = Daniela , name-list-style = vanc , doi = 10.1017/S147355041500021X, issue = 1, volume = 15, pages = 65–92, bibcode = 2016IJAsB..15...65V, doi-access = free


Human nutrition

Some cyanobacteria are sold as food, notably ''Arthrospira platensis (Spirulina (dietary supplement), Spirulina) and others'' (''Aphanizomenon flos-aquae'') . Some microalgae contain substances of high biological value, such as polyunsaturated fatty acids, amino acids, proteins, pigments, antioxidants, vitamins, and minerals. Edible blue-green algae reduce the production of pro-inflammatory cytokines by inhibiting NF-κB pathway in macrophages and splenocytes. Sulfate polysaccharides exhibit immunomodulatory, antitumor, antithrombotic, anticoagulant, anti-mutagenic, anti-inflammatory, antimicrobial, and even antiviral activity against HIV, herpes, and hepatitis.


Health risks

{{main, Cyanotoxin Some cyanobacteria can produce neurotoxins, cytotoxins, endotoxins, and hepatotoxins (e.g., the
microcystin Microcystins—or cyanoginosins—are a class of toxins produced by certain freshwater blue-green algae. Over 50 different microcystins have been discovered so far, of which microcystin-LR is the most common. Chemically they are cyclic heptapeptid ...
-producing bacteria genus microcystis), which are collectively known as
cyanotoxin Cyanotoxins are toxin A toxin is a harmful substance produced within living cells or organisms; synthetic toxicants created by artificial processes are thus excluded. The term was first used by organic chemist Ludwig Brieger (1849–1919), der ...
s. Specific toxins include anatoxin-a, guanitoxin, aplysiatoxin, cyanopeptolin,
cylindrospermopsin Cylindrospermopsin (abbreviated to CYN, or CYL) is a cyanotoxin produced by a variety of freshwater cyanobacteria. CYN is a Polycyclic compound, polycyclic uracil derivative (chemistry), derivative containing guanidine, guanidino and sulfate grou ...

cylindrospermopsin
, domoic acid, nodularin R (from ''Nodularia''), neosaxitoxin, and
saxitoxin Saxitoxin (STX) is a potent neurotoxin Neurotoxins are toxins that are destructive to nervous tissue, nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insult (medical), insultsSpencer 2 ...

saxitoxin
. Cyanobacteria reproduce explosively under certain conditions. This results in algal blooms which can become Harmful algal blooms, harmful to other species and pose a danger to humans and animals if the cyanobacteria involved produce toxins. Several cases of human poisoning have been documented, but a lack of knowledge prevents an accurate assessment of the risks,Blue-Green Algae (Cyanobacteria) and their Toxins
Hc-sc.gc.ca (2013-01-30). Retrieved on 2014-04-19.
Harmful Bloom in Lake Atitlán, Guatemala
fro
NASA Earth Observatory
retrieved on 9 January 2010.
and research by Linda Lawton, Fellowship of the Royal Society of Edinburgh, FRSE at
Robert Gordon University , mottoeng = Now by all your mastered arts , established = 1992 (origins mid-18th century) , type = Public In public relations Public relations (PR) is the practice of managing and disseminating information from an individual or a ...
, Aberdeen and collaborators has 30 years of examining the phenomenon and methods of improving water safety. Recent studies suggest that significant exposure to high levels of cyanobacteria producing toxins such as beta-Methylamino-L-alanine, BMAA can cause amyotrophic lateral sclerosis (ALS). People living within half a mile of cyanobacterially contaminated lakes have had a 2.3 times greater risk of developing ALS than the rest of the population; people around New Hampshire's Lake Mascoma had an up to 25 times greater risk of ALS than the expected incidence. BMAA from desert crusts found throughout Qatar might have contributed to higher rates of ALS in Gulf War veterans.


Chemical control

Several chemicals can eliminate cyanobacterial blooms from smaller water-based systems such as swimming pools. They include calcium hypochlorite, Copper(II) sulfate, copper sulphate, cupricide, and simazine.{{cite web , last= Main , first= D.C. , name-list-style = vanc , title= Toxic Algae Blooms , work= Veterinary Pathologist, South Perth , publisher= agric.wa.gov.au , date= 2006 , url= http://archive.agric.wa.gov.au/objtwr/imported_assets/content/lwe/water/watq/fn052_2004.pdf , access-date= 18 November 2014 The calcium hypochlorite amount needed varies depending on the cyanobacteria bloom, and treatment is needed periodically. According to the Department of Agriculture Australia, a rate of 12 g of 70% material in 1000 l of water is often effective to treat a bloom. Copper sulfate is also used commonly, but no longer recommended by the Australian Department of Agriculture, as it kills livestock, crustaceans, and fish. Cupricide is a chelated copper product that eliminates blooms with lower toxicity risks than copper sulfate. Dosage recommendations vary from 190 ml to 4.8 l per 1000 m2. Ferric alum treatments at the rate of 50 mg/l will reduce algae blooms. Simazine, which is also a herbicide, will continue to kill blooms for several days after an application. Simazine is marketed at different strengths (25, 50, and 90%), the recommended amount needed for one cubic meter of water per product is 25% product 8 ml; 50% product 4 ml; or 90% product 2.2 ml.


Climate change

Climate change is likely to increase the frequency, intensity and duration of cyanobacterial blooms in many eutrophic lakes, reservoirs and estuaries. Bloom-forming cyanobacteria produce a variety of neurotoxins, hepatotoxins and dermatoxins, which can be fatal to birds and mammals (including waterfowl, cattle and dogs) and threaten the use of waters for recreation, drinking water production, agricultural irrigation and fisheries. Cyanotoxin, Toxic cyanobacteria have caused major water quality problems, for example in Lake Taihu (China), Lake Erie (USA), Lake Okeechobee (USA), Lake Victoria (Africa) and the Baltic Sea.{{cite journal , doi = 10.1038/s41579-019-0222-5, title = Scientists' warning to humanity: Microorganisms and climate change, year = 2019, last1 = Cavicchioli, first1 = Ricardo, last2 = Ripple, first2 = William J., last3 = Timmis, first3 = Kenneth N., last4 = Azam, first4 = Farooq, last5 = Bakken, first5 = Lars R., last6 = Baylis, first6 = Matthew, last7 = Behrenfeld, first7 = Michael J., last8 = Boetius, first8 = Antje, last9 = Boyd, first9 = Philip W., last10 = Classen, first10 = Aimée T., last11 = Crowther, first11 = Thomas W., last12 = Danovaro, first12 = Roberto, last13 = Foreman, first13 = Christine M., last14 = Huisman, first14 = Jef, last15 = Hutchins, first15 = David A., last16 = Jansson, first16 = Janet K., last17 = Karl, first17 = David M., last18 = Koskella, first18 = Britt, last19 = Mark Welch, first19 = David B., last20 = Martiny, first20 = Jennifer B. H., last21 = Moran, first21 = Mary Ann, last22 = Orphan, first22 = Victoria J., last23 = Reay, first23 = David S., last24 = Remais, first24 = Justin V., last25 = Rich, first25 = Virginia I., last26 = Singh, first26 = Brajesh K., last27 = Stein, first27 = Lisa Y., last28 = Stewart, first28 = Frank J., last29 = Sullivan, first29 = Matthew B., last30 = Van Oppen, first30 = Madeleine J. H., journal = Nature Reviews Microbiology, volume = 17, issue = 9, pages = 569–586, pmid = 31213707, pmc = 7136171, display-authors = 29 Material was copied from this source, which is available under
Creative Commons Attribution 4.0 International License
Climate change favours cyanobacterial blooms both directly and indirectly. Many bloom-forming cyanobacteria can grow at relatively high temperatures. Increased thermal stratification of lakes and reservoirs enables buoyant cyanobacteria to float upwards and form dense surface blooms, which gives them better access to light and hence a selective advantage over nonbuoyant phytoplankton organisms. Protracted droughts during summer increase water residence times in reservoirs, rivers and estuaries, and these stagnant warm waters can provide ideal conditions for cyanobacterial bloom development.{{cite journal , doi = 10.1016/j.hal.2017.01.011, title = Impacts of the 2014 severe drought on the Microcystis bloom in San Francisco Estuary, year = 2017, last1 = Lehman, first1 = P.W., last2 = Kurobe, first2 = T., last3 = Lesmeister, first3 = S., last4 = Baxa, first4 = D., last5 = Tung, first5 = A., last6 = Teh, first6 = S.J., journal = Harmful Algae, volume = 63, pages = 94–108, pmid = 28366405, doi-access = free The capacity of the harmful cyanobacterial genus ''
Microcystis ''Microcystis'' is a genus of freshwater cyanobacteria that includes the harmful algal bloom-forming ''Microcystis aeruginosa''. Many members of a ''Microcystis'' community can produce neurotoxins and hepatotoxins, such as microcystin and cyanope ...
'' to adapt to elevated CO2 levels was demonstrated in both laboratory and field experiments.{{cite journal , doi = 10.1073/pnas.1602435113, title = Rapid adaptation of harmful cyanobacteria to rising CO2, year = 2016, last1 = Sandrini, first1 = Giovanni, last2 = Ji, first2 = Xing, last3 = Verspagen, first3 = Jolanda M. H., last4 = Tann, first4 = Robert P., last5 = Slot, first5 = Pieter C., last6 = Luimstra, first6 = Veerle M., last7 = Schuurmans, first7 = J. Merijn, last8 = Matthijs, first8 = Hans C. P., last9 = Huisman, first9 = Jef, journal = Proceedings of the National Academy of Sciences, volume = 113, issue = 33, pages = 9315–9320, pmid = 27482094, pmc = 4995953 ''Microcystis'' spp. take up CO2 and HCO3− and accumulate inorganic carbon in
carboxysome Image:Carboxysomes EM.jpg, 460px, Electron micrographs showing alpha-carboxysomes from the chemoautotrophic bacterium ''Halothiobacillus, Halothiobacillus neapolitanus'': (A) arranged within the cell, and (B) intact upon isolation. Scale bars indica ...

carboxysome
s, and strain competitiveness was found to depend on the concentration of inorganic carbon. As a result, climate change and increased CO2 levels are expected to affect the strain composition of cyanobacterial blooms.


Gallery

File:Lago de coatepeque de color.jpg, Cyanobacteria activity turns Coatepeque Caldera lake a turquoise color File:2010 Filamentous Cyanobacteria Bloom near Fiji.jpg, Cyanobacterial bloom near Fiji File:Sinilevää Köyliönjärvessä 3.jpg, Cyanobacteria in Lake Köyliö. File:Video- The Cyanobacteria- Oscillatoria and Gleocapsa.webm, Video – ''
Oscillatoria ''Oscillatoria'' is a genus of filamentous The word filament, which is descended from Latin ''filum'' meaning "Thread (yarn), thread", is used in English for a variety of thread-like structures, including: In commerce * Fiber or, more loosely ...

Oscillatoria
'' and ''Gleocapsa'' – with oscillatory movement as filaments of ''Oscillatoria'' orient towards light
{{clear


See also

{{div col, colwidth=18em * Archean Eon * Bacterial phyla, other major lineages of Bacteria * Biodiesel * Cyanobiont * Endosymbiotic theory * Geological history of oxygen * Hypolith {{div col end


References

{{Reflist, 30em ;Attribution {{CC-notice, cc=by2.5, url=https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0010821


Further reading

{{refbegin, 30em * {{cite book , first = Gillian , last = Cribbs , name-list-style = vanc , title = Nature's Superfood: the Blue-Green Algae Revolution , publisher = Newleaf , isbn = 978-0-7522-0569-4 , year = 1997 , edition = first * {{cite book , first = Marshall , last = Savage , name-list-style = vanc , author-link = Marshall Savage , title = The Millennial Project: Colonizing the Galaxy in Eight Easy Steps , publisher = Little Brown & Co , isbn = 978-0-316-77163-4 , year = 1994 , url = https://archive.org/details/millennialprojec00sava * {{cite book , vauthors = Fogg GE, Stewart WD, Fay P, Walsby AE , year = 1973 , title = The Blue-green Algae , publisher = Academic Press , location = London and New York , isbn = 978-0-12-261650-1
"Architects of the earth's atmosphere"
Introduction to the Cyanobacteria, University of California, Berkeley, 3 February 2006. * {{ cite book , vauthors = Whitton BA , chapter = Phylum Cyanophyta (Cyanobacteria) , title = The Freshwater Algal Flora of the British Isles , location = Cambridge , publisher = Cambridge University Press , isbn = 978-0-521-77051-4 , year = 2002 * {{cite journal , doi= 10.1080/09670262.2010.492914 , vauthors = Pentecost A, Franke U , year= 2010 , title= Photosynthesis and calcification of the stromatolitic freshwater cyanobacterium ''Rivularia'' , journal= Eur. J. Phycol. , volume= 45 , issue= 4 , pages= 345–53 , doi-access= free * {{cite book , veditors = Whitton BA, Potts M , year = 2000 , title = The Ecology of Cyanobacteria: their Diversity in Time and Space , publisher = Springer , isbn = 978-0-7923-4735-4 * {{cite web , url = http://www.paristechreview.com/2011/12/01/micro-algae-blue-oil/ , title = From Micro-Algae to Blue Oil , work = ParisTech Review , date = December 2011 , access-date = 2 March 2012 , archive-url = https://web.archive.org/web/20160417030653/http://www.paristechreview.com/2011/12/01/micro-algae-blue-oil/ , archive-date = 17 April 2016 , url-status = dead {{refend


External links

{{Commons category, Cyanobacteria
What are Cyanobacteria and What are its Types?

Webserver for Cyanobacteria Research

Diving an Antarctic Time Capsule Filled With Primordial Life
{{Plankton {{Microorganisms {{Bacteria classification {{Life on Earth {{Taxonbar, from=Q93315 {{Authority control Cyanobacteria, Phototrophic bacteria Photosynthesis Gram-negative bacteria Environmental chemistry Bacteria phyla