Anabaena

Anabaena
	Anabaena flosaquae
Scientific classification
Kingdom:	Bacteria
Phylum:	Cyanobacteria
Order:	Nostocales
Family:	Nostocaceae
Genus:	Anabaena; St. Vincent ex Bornet & Flah, 1886

For Anabaena A.Juss., a plant genus of the Euphorbiaceae, see its synonym Romanoa.

Anabaena is a genus of filamentous cyanobacteria, or blue-green algae, found as plankton. It is known for its nitrogen fixing abilities, and they form symbiotic relationships with certain plants, such as the mosquito fern. They are one of four genera of cyanobacteria that produce neurotoxins, which are harmful to local wildlife, as well as farm animals and pets. Production of these neurotoxins is assumed to be an input into its symbiotic relationships, protecting the plant from grazing pressure.

A DNA sequencing project was undertaken in 1999, which mapped the complete genome of Anabaena, which is 7.2 million base pairs long. The study focused on heterocysts, which convert nitrogen into ammonia. Certain species of Anabaena have been used on rice paddy fields, proving to be an effective natural fertilizer.

Species

Anabaena aequalis
Anabaena affinis
Anabaena angstumalis
- Anabaena angstumalis angstumalis
- Anabaena angstumalis marchica
Anabaena aphanizomendoides
Anabaena azollae
Anabaena bornetiana
Anabaena catenula
Anabaena circinalis
Anabaena confervoides
Anabaena constricta
Anabaena cyanobacterium
Anabaena cycadeae
Anabaena cylindrica
Anabaena echinispora
Anabaena felisii
Anabaena flosaquae
- Anabaena flosaquae flosaquae
- Anabaena flosaquae minor
- Anabaena flosaquae treleasei
Anabaena helicoidea
Anabaena inaequalis
Anabaena lapponica
Anabaena laxa
Anabaena lemmermannii
Anabaena levanderi
Anabaena limnetica
Anabaena macrospora
- Anabaena macrospora macrospora
- Anabaena macrospora robusta
Anabaena monticulosa
Anabaena nostoc
Anabaena oscillarioides
Anabaena planctonica
Anabaena raciborskii
Anabaena scheremetievi
Anabaena sphaerica
Anabaena spiroides
- Anabaena spiroides crassa
- Anabaena spiroides spiroides
Anabaena subcylindrica
Anabaena torulosa
Anabaena unispora
Anabaena variabilis
Anabaena verrucosa
Anabaena viguieri
Anabaena wisconsinense
Anabaena zierlingii

Nitrogen fixation by Anabaena

Under nitrogen-limiting conditions, vegetative cells differentiate into heterocysts at semi-regular intervals along the filaments. Heterocysts are cells that are terminally specialized for nitrogen fixation. The interior of these cells is microoxic as a result of increased respiration, inactivation of O₂-producing photosystem (PS) II, and formation of a thickened envelope outside of the cell wall. Nitrogenase, sequestered within these cells, transforms dinitrogen into ammonium at the expense of ATP and reductant—both generated by carbohydrate metabolism, a process that is supplemented, in the light, by the activity of PS I. Carbohydrate, probably in the form of sucrose, is synthesized in vegetative cells and moves into heterocysts. In return, nitrogen fixed in heterocysts moves into the vegetative cells, at least in part in the form of amino acids.^[1]

References

^ Herrero A and Flores E (editor). (2008). The Cyanobacteria: Molecular Biology, Genomics and Evolution (1st ed. ed.). Caister Academic Press. ISBN 978-1-904455-15-8 . {{cite book}}: |author= has generic name (help); |edition= has extra text (help)

External links

Sequenced Anabaena Genomes

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[Herrero-1] Herrero A and Flores E (editor). (2008). The Cyanobacteria: Molecular Biology, Genomics and Evolution (1st ed. ed.). Caister Academic Press. ISBN 978-1-904455-15-8 . {{cite book}}: |author= has generic name (help); |edition= has extra text (help)

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