Cyanobacteria : Defination, Structure, Appearance, Importance, FAQs

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.

Cyanobacteria : Defination, Structure, Appearance, Importance, FAQs


Definition of Cynobacteria

Cynobacteria are a group of microscopic organisms that have the ability to carry out photosynthesis. Cynobacteria is 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 have the ability to 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.


Appearance of cynobacteria :

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:

  1. They have the ability to produce photosynthesis.
  2. They were formerly known as blue-green algae, cyanophilic or cyanophytic.
  3. They can live in different types of temperatures.
  4. They can produce a number of toxins in drinking water and seas that cause disease.
  5. When grown en masse, they can easily be thought of as a green color in water.
  6. They can cause a number of diseases that damage vital organs such as the liver and can also cause abdominal pain, vomiting and diarrhea.
  7. Depending on the type of cyanobacteria, they can damage the central nervous system causing paralysis, cardiac arrest and death.
  8. They promote the development of cancer and degenerative diseases.
  9. They reproduce asexually, but also have some unique reproduction mechanisms such as binary fission, multiple fission and hatching
Cyanobacteria : Defination, Structure

Structural Organization of Cynobacteria

They can be monocytes and multicells. The star can be colonial or nematode. Monocytes foms 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.

Cell structure of Cynobacteria

  1. 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 rhomosome. Like bacteria>, small circular pieces of DNA can also appear in addition to the nucleoid. They are known as plasmids or transducers.
  2. The cell wall is always covered by a mucosal sheath, consisting largely of mucosal peptide.
  3. The cellular protoplast often differentiates into external colored chromoplasm and internal colorless centroplasm.
  4. There is a coiled membrane plasma growth called a lamellar body.
  5. The protoplast does not have an organic membrane and contains 70S ribosomes.
  6. 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.
  7. 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 phycovilines, i.e., phycocyanin (blue), allophycocyanin (blue) and phycoerythrin (red).
  8. 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.
  9. The cell contains reserve food material in the form of a special starch called cyanophycean starch. Other granules present in a cyanobacterial cell are voltin granules and polyhedral bodies.

Read :

  1. Mitochondria 
  2. Somatic Cell
  3. Flagella Structure & Functions
  4. Plant Cell
  5. Animal Cell


Metabolism of Cynobacteria

They are the most self-sustaining organisms, because most of them are able to 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 Cynobacteria

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 death of interfering cells (necrides).

Read :

  1. Mitosis
  2. Meiosis
  3. Karyokinesis
  4. Cytokinesis


Function of cyanobacteria

  1. Cyanobacteria have the function of participating in about 30% of the photosynthesis that occurs on the planet every day and are also an important part of the composition of the atmosphere. 
  2. 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.
  3. 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. 
  4. They fix nitrogen in soil, coral reefs and different water environments, making nitrogen available to many types of ecosystems.


Importance of cyanobacteria

  1. They play an important role in the evolution of the aerobic spirits of life.
  2. They convert atmospheric nitrogen into ammonium compounds and the excess of these compounds is secreted enriching the soil.
  3. Cyanobacteria such as Nostoc and Anabaena have been used to reclaim soils.
  4. They benefit the partner by providing nitrogenous compounds due to their ability to fix nitrogen.
  5. Some blue bacteria such as Nostoc serve as food
  6. Lyngbia extract, a cyanobacterium used to treat antibiotics.
  7. 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.

Freaquently Asked Questions (FAQs) Cynobacteria 

Why cyanobacteria are important?
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.

What do cyanobacteria to humans?
Cyanotoxins can cause gastrointestinal, nervous, hepatic or dermal toxicity. The signs and symptoms reported after exposure also vary depending on the route of exposure. Ingestion: Gastrointestinal (GI) effects include nausea, vomiting, diarrhea, and mild liver enzymes.

Where cyanobacteria are found ?
Cyanobacteria are found in almost every terrestrial and aquatic habitat - oceans, fresh water, wet soil, temporarily wet rocks in deserts, bare rocks and soil, and even rocks in Antarctica. They can appear as planktonic cells or form phototrophic biofilms.

Are cyanobacteria bacteria or algae?
These are also referred to as blue-green algae. Although they are capable of conducting oxygen-producing photosynthesis and living in many of the same environments as eukaryotic algae, cyanobacteria are gram-negative and therefore prokaryotic.

Cyanobacteria Good or Bad?
Cyanobacteria can help by providing nutrients to plants such as rice and beans. However, cyanobacterial blooms can also be dangerous. Harmful cyanobacterial algal blooms - known as HABs or CyanoHABs - can consume oxygen in the water and block out the sunlight that freshwater plants and animals must survive.

Can cyanobacteria kill you?
Blooming cyanobacteria can produce cyanotoxins in such concentrations that they poison and even kill animals and humans. ... Among the cyanotoxins are some of the most powerful natural poisons known, including poisons that can cause rapid death from respiratory failure.


What are the example of cyanobacteria?
  1. Nostocales
  2. Chroococcales
  3. Oscillators
  4. Prochlorophytes
  5. Synechococcales

Are Cyanobacteria Harmful to Humans?
Cyanobacteria, or blue-green algae, are found worldwide in calm waters rich in nutrients. Some species of cyanobacteria produce toxins that infect animals and humans. People can be exposed to cyanobacterial toxins by drinking or swimming in contaminated water.

Can you see cyanobacteria?
You may or may not see cyanobacterial blooms. Sometimes they stay below the surface of the water, sometimes they float on the surface. The flowers can be blue, bright green, brown or red. The blooms sometimes look like a color floating on the surface of the water.

What are blue-green algae? 
Although often referred to as algae, blue-green algae are not algae at all, but types of bacteria called cyanobacteria.

Can cyanobacteria ficed nitrogen?
Cyanobacteria are oxygen photosynthetic bacteria that are widespread in marine, freshwater, and terrestrial environments, and many of them are capable of securing atmospheric nitrogen. This strategy is known as spatial separation of oxygen photosynthesis and nitrogen fixation.

Does blue-green algae have chlorophyll?
Blue-green algae (cyanobacteria) are a group of prokaryotic, autotrophic microorganisms that contain photosynthetic pigments (chlorophyll and phycocyanin).

What is the difference between Rhizobium and cyanobacteria in the way nitrogen is attached to the soil?
Most rhizomes have well-preserved oozing genes that encode signals, ozonating agents, that are perceived by the plant. Plant cyanobacterial symbiosis is diverse, but mainly involves a microbial genus, Nostoc.

How Cynobacteria reproduce
Cyanobacteria reproduce asexually, either by binary or multiple cleavage into single-celled and colonial forms or by fragmentation and spore formation in nematode species. Under favorable conditions, cyanobacteria can reproduce at an explosive rate, forming dense concentrations called flowers.

Can cyanobacteria reproduce sexually?
Cyanobacteria reproduce through cell division, while some nematode species produce specialized plant fragments called hormones. There is also evidence of sexual reproduction (mating) and genetic recombination.


What is the function of cyanobacteria?
  1. Cyanobacteria are important in the nitrogen cycle.
  2. Cyanobacteria are very important organisms for the health and growth of many plants. 
  3. It is one of the few groups of organisms that can convert inert atmospheric nitrogen into an organic form, such as nitrates or ammonia.