Table of Contents
Anabaena Definition
Anabaena is the genus of filamentous cyanobacteria. These bacteria can form colonies composed of either single cells or filamentous groups of cells. The cells are photosynthetic; as a byproduct of photosynthesis, they generate oxygen gas. It has been proven that several Anabaena species work well as natural fertilisers by being utilised on rice paddies.
One of four cyanobacterial genera, Anabaena, produces neurotoxins that are toxic to domestic animals, farm animals, and pets in addition to the local fauna. It is believed that the production of these neurotoxins contributes to its symbiotic interactions, which protect the plant against grazing stress.
Scientific Classification
|
Domain |
Bacteria |
|---|---|
|
Phylum |
Cyanobacteria |
|
Class |
Cyanophyceae |
|
Order |
Nostocales |
|
Family |
Nostocaceae |
|
Genus |
Anabaena |
Anabaena Variabilis
Among the filamentous cyanobacteria species is one called Anabaena variabilis. It is a photosynthetic prokaryote that fixes atmospheric nitrogen gas and transforms it into a form that plants can utilise. It can be found in many aquatic habitats including soil, freshwater, and saltwater. It develops colonies that are either spherical or filamentous.
As a nitrogen-fixing bacteria, Anabaena variabilis can transform atmospheric nitrogen into a form that plants can utilise. It is necessary to convert nitrogen gas into a format that plants can utilise, as they cannot use it directly.
Structure
The structure of Anabaena is filamentous. Its filament is similar to Nostoc‘s filament. Nostoc and Anabaena trichomes can often be hard to distinguish from one another. However, mucilage covers the Nostoc filaments, combining to form a colony, while in Anabaena, it is not present.
Anabaena has a filament made up of a string of beaded cells. There are several intercalary heterocysts in the trichome. Heterocysts have a vegetative cell-like morphology. Typically, the filaments are straight. However, they could be uneven or circinate. A sheath contains only one filament at a time. Hyaline and watery gelatinous sheaths are always present.
Occurrence
Anabaena is observed as plankton. It is notable for its capacity to fix nitrogen. They develop symbiotic bonds with some plants such as the mosquito fern. There are some endophytic Anabaena species. They reside in the Cycas and Azolla roots.
Anabaena is present in all forms of water. Nutrient-rich waterways can support large-scale growths or blooms. When the cells of these blooms decompose, the water becomes discoloured, and a foul smell is released.
Nitrogen Fixation
The process of turning atmospheric nitrogen (N2) into ammonia (NH3) is known as nitrogen fixation (NH3). Specific bacteria known as nitrogen-fixing bacteria are responsible for this process.
One Anabaena cell out of every ten will develop into a heterocyst when the ambient nitrogen level is low. Heterocysts then exchange the byproducts of photosynthesis for fixed nitrogen, which they supply to nearby cells. These nitrogen-fixing cells can no longer engage in photosynthesis. Nitrogenase is the enzyme that heterocysts use to fix nitrogen. Nitrogenase reduces N2 into two molecules of ammonia (NH3).
The blue-green algae Anabaena azollae and fern Azolla maintain a symbiotic relationship where the fern provides the alga with a habitat, and the alga provides the nitrogen. Since it can quickly colonise freshwater environments and develop rapidly, this has led to the plant being referred to as a “super-plant.” Phosphorus generally keeps it from growing, and an oversupply of it from chemical runoff frequently causes Azolla blooms.
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