Cyanobacteria (Gk. Cyano = blue, bacterium = rod) or blue-green algae are Gram-negative photosynthetic prokaryotes, which are the most primitive organisms that have oxygen photosynthesis. They are the most successful and self-sustaining organisms on earth and survived successfully for more than three billion years. They added oxygen to the atmosphere, which is essential for the existence of aerobic forms of living organisms.
Definition of Cyanobacteria
Cyanobacteria are a group of microscopic organisms that can carry out photosynthesis. Cyanobacteria are also known as cyanophytes They are a type of gram-negative bacteria that also contain chlorophyll and are present in fresh, salty, brackish waters and in estuaries. They can produce a series of dangerous toxins for humans and for this reason they are considered by the World Health Organization as a health problem that is on the rise.
The appearance of cyanobacteria :
They occur mainly in freshwater forms, few are in the sea. Some species grow in hot water sources having a temperature range of 70 ° C to 75 ° C (eg Phormidium) and others grow at very low temperatures in the polar regions (eg Nostoc, Schizothrix, etc.). The Red Sea is named because of the abundant appearance of one cyanobacterium, erythraeum, which gives the water its red color. They occur in a symbiotic relationship with almost every group of eukaryotes.
Characteristics of cyanobacteria
Among its main features are the following:
- They can produce photosynthesis.
- They were formerly known as blue-green algae, cyanophilic, or cyanophyte.
- They can live in different types of temperatures.
- They can produce several toxins in drinking water and seas that cause disease.
- When grown en masse, they can easily be thought of as a green color in water.
- They can cause several diseases that damage vital organs such as the liver and can also cause abdominal pain, vomiting, and diarrhea.
- Depending on the type of cyanobacteria, they can damage the central nervous system causing paralysis, cardiac arrest, and death.
- They promote the development of cancer and degenerative diseases.
- They reproduce asexually, but also have some unique reproduction mechanisms such as binary fission, multiple fission, and hatching
Structural Organization of Cyanobacteria
They can be monocytes and multi cells. The star can be colonial or nematode. Monocytes’ forms can be spherical or oval in shape. The filamentous form consists of one or more cell clones, called hair cells, surrounded by a mucous sheath. A filament may contain one (e.g. Oscillatoria) in many capillaries (e.g. Schizothrix). Cyanobacteria are characterized by the absence of a whip even in kinetic forms, although most of them are kinetic.
The cell structure of Cyanobacteria
- The cell structure of cyanobacteria is essentially similar to that of bacteria. The cell lacks a well-defined nucleus and the chromatin material is centrally located, resembling a bacterial chromosome. Like bacteria>, small circular pieces of DNA can also appear in addition to the nucleoid. They are known as plasmids or transducers.
- The cell wall is always covered by a mucosal sheath, consisting largely of the mucosal peptide.
- The cellular protoplast often differentiates into external colored chromoplasts and internal colorless cytoplasm.
- There is a coiled membrane plasma growth called a lamellar body.
- The protoplast does not have an organic membrane and contains 70S ribosomes.
- The vacuum gaps found in bacterial cells are absent. Instead, the cell may contain a vacuum filled with gas that helps regulate the body’s buoyancy in the water.
- The hallmark of a cyanobacterial cell is the presence of a system of photosynthetic plates called follicles, which make the structure more complex compared to that of bacteria. The characteristic photosynthetic pigments present in follicles are chlorophyll α and phycobilins, i.e., phycocyanin (blue), allophycocyanin (blue), and phycoerythrin (red).
- Sometimes the same species, when grown at different light wavelengths, shows changes in pigment composition. In this way, algae are believed to be able to absorb the maximum amount of light available for photosynthesis. This ability to change color with a complementary effect to light is known as the Gaidukov effect (first introduced by Gaidukov) or complementary color adjustment. e.g. Trichodesmium erythreum causes red sea.
- The cell contains reserve food material in the form of a special starch called cyanophycean starch. Other granules present in a cyanobacterial cell are volts granules and polyhedral bodies.
Metabolism of Cynobacteria
They are the most self-sustaining organisms, because most of them can convert atmospheric nitrogen into ammonium compounds in addition to using atmospheric CO, to synthesize organic food during photosynthesis. Nitrogen stabilization under anaerobic conditions occurs mainly in specialized cells called heterocysts. Heterocysts are large, pale mucous membranes without dense cell walls that are impermeable to oxygen.
Reproduction of Cyanobacteria
Cyanobacteria reproduce plant and asexually. Sexual reproduction is usually absent. However, gene recombination is reported. Cyanobacteria multiply on
Binary cleavage: Appears in single-celled forms. The daughter cells are formed by amitotic division, they separate immediately after division.
Fragmentation: Appears in nematode forms. The yarn splits into small pieces or fragments that grow to form new yarns.
Hormones: They are small sections of hair that are separated from the parent due to the death of interfering cells (decides).
Function of cyanobacteria
- Cyanobacteria have the function of participating in about 30% of the photosynthesis that occurs on the planet every day and is also an important part of the composition of the atmosphere.
- They play an important role in the proper development of plant life, to better understand it, we can say that the chloroplast that is inside a plant cell and that produces its food is basically a cyanobacterium.
- Having the ability to process nitrogen from the atmosphere and then convert it to organic form, this process is extremely important for many plants to grow properly.
- They fix nitrogen in the soil, coral reefs, and different water environments, making nitrogen available to many types of ecosystems.
Importance of cyanobacteria
- They play an important role in the evolution of the aerobic spirits of life.
- They convert atmospheric nitrogen into ammonium compounds and the excess of these compounds is secreted enriching the soil.
- Cyanobacteria such as Nostoc and Anabaena have been used to reclaim soils.
- They benefit the partner by providing nitrogenous compounds due to their ability to fix nitrogen.
- Some blue bacteria such as Nostoc serve as food
- Lyngby extract, is a cyanobacterium used to treat antibiotics.
- Some blue bacteria such as Microcystis aeruginosa, Anabaena jlosaquae, Aphanizomenon flos-aquae secrete toxins in the surrounding area, which harm aquatic animals and even human beings.
Frequently Asked Questions (FAQs) Cyanobacteria
- Cyanobacteria are important in the nitrogen cycle.
- Cyanobacteria are very important organisms for the health and growth of many plants.
- It is one of the few groups of organisms that can convert inert atmospheric nitrogen into an organic form, such as nitrates or ammonia.