Cyanobacteria

This contains the basic information of cyanobacteria..

1. Cyano bacteria A.Ponsrinivasan , M.F.Sc – I, DAAHM

2. Cyanobacteria Commonly known as blue- green algae . Autotrophic (Photosynthetic). Contain chlorophyll a , phycocyanin (blue) and phycoerythrin (red). They live in aquatic environments including oceans, ponds, lakes, tidal flats, and moist soil. They exist mostly as colonies and filaments and sometimes as single cells .

3. Some filamentous forms can move. For example, filamentous forms such as Oscillatoria sp. and Nostoc sp. rotate in a screw like manner. Produce gelatinous capsules which are often lighter than water and therefore help keep the algae up near the surface of the water. Reproduction in by fission . Prokaryotic cell. Lack chlorophyll b . The photosynthetic product is stored in their own form of starch , which is similar to animal glycogen.

4. Forms of Cyanobacteria e.g . Gloeocapsa sp 1.Unicellular or aggregate

5. e.g . Microcystis sp 2.Colony

6. e.g . Anabaena sp 3. Filamentous forms a)Unbranched

7. e.g . Stigonema sp 3.Filamentous forms b ).Branched

8. Cell structure The cell structure is very primitive. Each cell is composed of two parts: cell wall protoplast. The cell wall is composed of 2 layers : Chromoplast Central body Cell wall

9. The protoplast consists of 2 parts: peripheral pigmented ( coloured ) region surrounding a colourless central region . It contains the blue pigment phycocyanin together with chlorophyll and known as chromoplasm . The colourless inner region (central body) contains several chromatin granules (DNA) which represent a primitive type of nucleus that lacks nuclear membrane and nucleoli Chromoplast Cell wall Central body

10. Cyanobacterial cell

11. Nostoc Grows in water and on damp soils. Unbranched filaments with barrel-like cells. Certain enlarged cells appear at intervals, which are known as heterocysts . Its transparent and thick walls. The whole filament is surrounded with gelatinous material. Nostoc

12. Reproduction Sexual reproduction is not known . By Akinetes . By fission. Vegetative reproduction Asexual reproduction.

13. By fragmentation Filament breaks into fragments. Each gives rise to a new filament. Usually fragmentation occurs at the heterocysts This fragment is capable of creeping movements in the gelatinous sheath until it escapes and grows into a new filament. Vegetative reproduction

14. Asexual reproduction A ) By fission. A constriction is formed in the middle of the cell extends from the surface inwards towards the center Division into two cells leads to the increase in number of cells per filament without production of a new one.

15. B) By Akinetes vegetative cells enlarge in size become rich in food materials and form a thick wall These akinetes are yellow or brown in colour and they are very resistant to un- favourable conditions When the conditions are favourable the akinetes germinate into new filaments. 2. Asexual reproduction.

16. Symbioses During nitrogen fixation, an enzyme known as nitrogenase transfers several pairs (three pairs) of electrons and protons to the nitrogen molecule to create two ammonia molecules . This is then added to glutamic acid to form glutamine (in the plant's cells) that in turn provides amide nitrogen used for the synthesis of amino acids as well as components of DNA and RNA. In this relationship, cyanobacteria, which are nitrogen-fixers benefit from carbon dioxide that is produced by the host (algae etc )

17. What causes Cyanobacterial blooms? Anthropogenic nutrition enrichment, altered hydrologic patterns, and changes in the Earth’s climate accelerate the intensity, duration, and frequency of CyanoHABs . Extensive nutrient supply ( nitrogen:N and phosphorus:P ), rising atmospheric CO2 levels, and higher water temperatures intensify the Cyanobacterial growth Nutrient pollution feeds Cyanobacteria Cyanobacteria are actively exploiting man-made pollution of water systems. They thrive on nutrient pollution and eutrophication. Urban, agricultural, and  Industrial activities increase the nutrient pollution , salinization, and eutrophication of waterways. This stimulates more frequent and persistent Cyanobacterial blooms .

18. Climate change exacerbates cyanobacterial blooms Climate change is another powerful catalyst for Cyanobacterial expansion. Rising temperatures and changes in the precipitation patterns stimulate more frequent and extensive CyanoHABs . Elevated temperatures lead to an earlier onset and longer duration of thermal stratification, which makes the buoyant cyanobacteria more competitive

19. Treatment from Cyanobacteria

20. Cyanobacterial Toxins: The cyanobacteria are proving to be a source of a large number of novel organic compounds with biological activity

21.  Toxic Cyanobacteria Genus Toxins produced Anabaena Anatoxins, Aplysiatoxins , Microcystins , Saxitoxins Anabaenopsis Microcystins Aphanizomenon Saxitoxins, Cylindrospermopsins Cylindrospermopsis Cylindrospermopsins ,  Saxitoxins Hapalosiphon Microcystins Lyngbya Aplysiatoxins ,  Iyngbyatoxin Microcystis Microcystins Nodularia Nodularian Microcystins Microcystins Phormidium  ( oscillatoria ) Anatoxin Planktothrix  ( oscillatoria ) Anatoxins, Aplysiatoxins , Microcystins , Saxitoxins Schizothrix Aplysiatoxins

22. Importance of Cyanobacteria Nitrogen fixation Can be used as food (Japan, Chad, and China) Can pollute the water source (Lake). High concentration may cause fish toxicity and other microorganism.

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