Cyanobacteria (known as blue-green algae) are single-celled microscopic organisms mostly found in different types of water. they like to live in brackish, fresh, and marine water. using sunlight, they can make their own food. Characteristics of Cyanobacteria are: they contain chlorophyll and carotenoids, photosynthetic pigments, carbohydrates stored in glycogen, no flagella for movement, etc. the blue-green algae are also important economically such as they are colonizers of bare and barren areas, served as food to several aquatic animals, possess the ability of nitrogen fixation, can grow on the walls and roofs of building, etc.
Economic Importance of Cyanobacteria
- They help in the reclamation of alkaline soil.
- Cyanobacteria have heterocysts. These heterocysts are involved in the fixation of atmospheric nitrogen.
- They release 02 in the environment during their photosynthetic activity.
- Osicllatoria and a few other cyanobacteria can be used as pollution indicators.
- They develop a symbiotic relationship with protozoa fungi and plants. The nitrogen-fixing species form an association with angiosperms. They are photosynthetic partners in most of the Lichen (algae + fungi) associations.
- Many species of cyanobacteria from water bloom. They produce an unpleasant smell. A large amount of organic matter suspends in this water bloom. It makes the water unfit for drinking.
- Some species produce toxins in the water. The toxin kills the animals which drink this water.
- Super Blue-green algae form expensive scum. These are single-celled cyanobacteria. They produce their food through photosynthesis. These blue-green algae are a complete whole food. It contains 60% protein. This protein has all essential amino acids in perfect balance.
Characteristics of Cyanobacteria
Cyanobacteria are the largest and most diverse group of photosynthetic bacteria. They were previously known as blue-green algae. They show the following characteristics:
- Cell type: They are true prokaryotes. They lack a true nucleus and nuclear membrane.
- Size and Shape: They vary greatly in size and shape. They range in diameter from Ito 10µm.
- Vegetative structure: They may be unicellular or form colonies of different shapes or form filaments. The filament is composed of trichomes. A trichome is a chain of cells. Each filament is surrounded by a mucilaginous sheath
- Cell wall: They have a gram-negative type cell wall.
- Locomotion: They lack flagella. They use gas vesicles to move in the water. Many filamentous species show gliding movements.
- Photosynthetic System: Their photosynthetic system closely resembles the eukaryotes. They have chlorophyll and photosystem II. Cyanobacteria carry out oxygenic photosynthesis as they use water as an electron donor and release oxygen during photosynthesis. They use phycobilins as accessory pigments. Photosynthetic pigment and electron transport chain components. These pigments are located within the thylakoid membrane. These pigments are linked with particle phycobilisomes. A blue pigment Phycocyanin is their predominant phycobilin. Cyanobacteria fix CO2 through the Calvin Cycle.
- Reserve food material: Their reserve food material is glycogen.
- Reproduction: Cyanobacteria reproduce asexually by the following methods:
- Binary fission
- Fragmentation: The filament of the cyanobacteria breaks from special cells called heterocysts. The broken pieces of a filament are called hormogonia. These hormogonia grow from a new filament.
- Akinetes: These are special reproductive cells. Akinetes are thick-walled, enlarged reproductive cells.
(Recap on Characteristics of Cyanobacteria)
- These are also called blue-green algae or cyanophytes.
- These are water-living organisms.
- Their body is filamentous i.e. consists of a thread-like structure, called a filament.
- They contain blue and green pigments.
- Cyanobacteria are autotrophs i.e. manufacture their on food material.
- The arc prokaryotes i.e. contain an incomplete nucleus.
Types of Cyanobacteria
- Cylindrospermopsis raciborskii
- Anabaena circinalis
Importance of Bacteria
Bacteria have both positive and negative importance. They play a very important role in the life of human beings.
1. Decaying of dead bodies:
Bacteria decompose the dead remains of plants, animals, and human beings into simpler compounds. In this way, they help to clean the world.
2. Bacteria in industries:
- Bacteria are used in the dairy industry they change the milk into curd.
- They are used in the formation of butter and cheese from milk.
- From certain bacteria, antibiotics are obtained, for example, Terramycin, Streptomycin, Neomycin, etc.
- Bacteria are used in the preparation of alcohol and vinegar.
- Bacteria are also used in the leather industry.
Certain bacteria are present in the intestine of man and help in the digestion of cellulose.
4. The fertility of soil:
Bacteria increase the fertility of the soil by adding organic substances due to the decompositions of dead bodies.
5. Nitrogen Fixation:
Bacteria also take part in nitrogen fixation i.e. they convert Nitrogen into its compounds like nitrites and nitrates. These compounds are used by plants.
Bacteria spoil our foodstuff in large amounts through the chemical process. It is a great loss.
2. Diseases in Man:
Bacteria are responsible to cause various diseases in men and other animals, such as Tuberculosis (T.B.), Pneumonia, Cholera, Typhoid, Tetanus, Syphilis, Diphtheria, etc.
3. Diseases in Plants:
Bacteria also cause disease in various plants, such as Citrus Canker, Fire blight of apple, Ring disease of potato, wilt of Solanaceae plants, etc.
10 Examples of Cyanobacteria
The following ten are the most common examples of cyanobacteria:
Types of Cyanobacteria
FAQs (Frequently Asked Questions)
Why are cyanobacteria so important?
cyanobacteria are considered so important positively and negatively for human beings, as they are regarded as an important source of biofuels and nutrients. helps for the decaying of dead bodies, is important in the digestion of cellulose, is important for nitrogen fixation, etc. while a negative perspective, they are responsible for various diseases in our bodies and plants, and also spoil the foodstuff.
What do cyanobacteria do to humans?
they are responsible for many diseases in humans like earache, conjunctivitis, sore throat, rhinitis, and swollen lips.
What is so special about cyanobacteria?
cyanobacteria belong to the diverse phylum of photoautotrophic prokaryotes. this phylum is very large. they possess a unique combination of pigments and their ability to perform oxygenic photosynthesis. cyanobacteria are keen to live in colonial aggregates.
Is cyanobacteria a plant or animal?
since the morphology of cyanobacteria is very diverse and belongs to the photosynthetic prokaryotic microorganisms. they are also called blue-green algae and are classified as plants.