Characteristics of Cyanobacteria
- Cell type: They are true prokaryotes. They lack 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. Trichome is chain of cell. Each filament is surrounded by mucilaginous sheath
- Cell wall: They have gram negative type cell wall.
- Locomotion: They lack flagella. They use gas vesicle to move in the water. Many filamentous species show gliding movements.
- Photosynthetic System: Their photosynthetic system is closely resembled to the eukaryotes. They have chlorophyll and photosystem II. Cyanobateria carry out oxygenic photosynthesis as they use water as 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 particles phycobilisomes. A blue pigment Phycocyanin is their predominant phycobilins. Cyanobacteria fix CO2 through the Calvin Cycle.
- Reserve food material: Their reserve food material is glycogen.
- Reproduction: Cyanobacteria reproduce asexually by following methods:
- Binary fission
- Fragmentation: The filament of the cyanobacteria breaks to from special cells called hetercysts. The broken pieces of a filament are called hormogonia. These hormogonia grow to from new filament.
- Akinetes: These are special reproductive cells. Akinetes are thick walled, enlarge reproductive cells.
(Brief note on Characteristics of Cyanobacteria)
- These are also called blue green algae or cynophyta.
- These are water living organisms.
- Their body is filamentous i.e. consists of thread like structure, called filament.
- They contain blue and green pigments.
- Cyanobacteria are autotrophs i.e. manufacture their on food material.
- They arc prokaryotes i.e. contain incomplete nucleus.
Economic Importance of Cyanobacteria
- They help in reclamation of alkaline soil.
- Cyanobacteria have hetercysts. These hetercysts are involved in the fixation of atmospheric nitrogen.
- They release 02 in the environment during their photosynthetic activity.
- Osicllatoria and few other cyanobacteria can be used as pollution indicator.
- They develop symbiotic relationship with protozoa fungi and plants. The nitrogen fixing species form association with angiosperms. They are photosynthetic partner in most of the Lichen (algae + fungi) associations.
- Many species of cyanobacteria form water blooms. They produce 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 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.
Importance of Bacteria
Bacteria have both positive and negative importance. They play very important role in the life of human being.
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 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 leather industry.
Certain bacteria are present in the intestine of man and help in the digestion of cellulose.
4. Fertility of soil:
Bacteria increase the fertility of 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 the plants.
Bacteria spoil our food stuff in large amount by the chemical process. It is a great loss.
2. Diseases in Man:
Bacteria are responsible to cause various diseases in man and other animals, such as Tuberculosis (T.B.), Pneumonia, Cholera, Typhoid, Tetanus, Syphilis, and 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.