What are cyanophyta؟

Classification Kingdom: Monera (Prokaryotes) Class: Cyanophyceae (Cyanobacteria), (Cyanophyta), (Blue green algae), (Blue green bacteria) Prokaryotic organisms that obtain their energy through photosynthesis.

Characters It has been found from 2.8 billion years ago. about 150 genera with about 2000 species. Most are found in fresh water, while others are marine, occur in damp soil, or even temporarily moistened rocks in deserts. A few are endosymbionts in lichens, plants. Lichens are symbiotic associations of a fungus with a cyanobacterium. Contain pigments (Chlorophyll a and phycocyanin ). Storage product is Cyanophycin starch.

Cells diversity Include unicellular and colonial species. Aggregations of cells into "trichomes" occurs. Filaments occur when trichomes are surrounded by a sheath. Colonies may form filaments, sheets or even hollow balls. Many cyanobacteria also form motile filaments, called hormogonia, that travel away by gliding from the main biomass to bud and form new colonies elsewhere.

Cell differentiation Some filamentous colonies show the ability to differentiate into several different cell types: vegetative cells, the normal photosynthetic cells. Akinetes, the climate-resistant spores. Heterocysts, which contain the enzyme nitrogenase, vital for nitrogen fixation.

Importance Certain cyanobacteria produce cyanotoxins, sometimes a mass- reproduction of cyanobacteria results in algal blooms. At least one secondary metabolite, cyanovirin, has shown to possess anti-HIV activity (Human Immunodeficiency Virus) . Some cyanobacteria are sold as human food supplies , as Spirulin.a Some hydrogen producing cyanobacteria are being considered as an alternative energy source.

Organism identification Physical appearance of cells/filaments/colonies Presence and location of heterocysts Presence and location of akinetes Presence of sheath Shape and size of cells Shape of colony (tangled filaments or a straight line) Physiological health of cells, are they healthy or degrading

Order : Nostocales Family: Nostocaceae Genus : Anabaena sp. A heterocyst-forming, photoautotrophic filamentous cyanobacteria. Found as plankton in shallow water and on moist soil Occur in both solitary and colonial forms Extensive growth of Anabaena may form water blooms and produce a potent toxins.

Heterocyst About one cell out of every ten will differentiate into a heterocyst. Heterocysts supply neighboring cells with fixed nitrogen in return for the products of photosynthesis, that they can no longer perform. the nitrogen fixing enzyme in heterocysts, nitrogenase, is unstable in the presence of oxygen. the developing heterocyst builds three additional layers outside the cell wall, giving it its characteristic enlarged and rounded appearance, thus the rate of oxygen diffusion into heterocysts is 100 times lower than of vegetative cells. The presence of photosystem II is eliminated, and the rate of respiration is stepped up to use up excess oxygen.

Order : Oscillatoriales Genus : Oscillatoria sp. Cylindrical or sometimes slightly tapering, unbranched filaments (trichomes), often with a rounded apical cell. Other cells are discoid, with further developing cross-walls. There are no heterocysts or akinetes. Found in damp soil or on dripping rocks, in freshwater, in the sea and in hot springs. Is named for the oscillation in its movement. Filaments in the colonies can slide back and forth against each other until the whole mass is reoriented to its light source. Reproduces by fragmentation. Forms long filaments of cells which can break into fragments called hormogonia. Breaks in the filament usually occur where dead cells(necridia) are present.

Order : Oscillatoriales Family:Phormidiaceae Genus : Spirulina sp. It is a simple, one-celled form of Microscopic algae that thrives in warm, alkaline fresh-water bodies. Free-floating filamentous cyanobacteria characterized by cylindrical, multicellular trichomes in an open left-hand helix. The name "spirulina" is derived from the Latin word spiral used as a human dietary supplement as well as a whole food and is available in tablet, flake, and powder form. It is also used as a feed supplement in the aquaculture, aquarium, and poultry industries "food of the future" Spirulina contains an unusually high amount of protein, between 65% and 77% by dry weight, containing all essential amino acids. Spirulina contains vitamin B1, B2, B3, B6, B9,C,D and E. Spirulina is a rich source of potassium, calcium, chromium, copper, iron, magnesium, manganese, phosphorus, selenium, sodium, and zinc.

Medicinal Properties Spirulina For those with hyperlipemia. In those who have higher total cholesterol levels In the narrowing and hardening of vessels and the loss of vascular elasticity. The aggravation of blood circulation induces heart diseases and stroke. For those with liver diseases. For those with diabetes mellitus.

Order : Nostocales family: Nostocaceae Genus : Cylindrospermum sp. has curved or slightly coiled cylindrical filaments composed of square or rectangular vegetative cells. The trichomes are enclosed in loose, colorless, homogeneous mucilage. Normally, basal heterocysts form from the terminal vegetative cells at one or both ends of the filament. Cultured specimens may have both intercalary and terminal heterocysts. The heterocysts are conical, oval, or ellipsoidal with a single pore. Large, ornamented, ellipsoidal or spherical akinetes usually develop from the lowermost vegetative cell adjacent to the terminal heterocysts, but are not always present in culture. There may be a single akinete or as many as seven. Many species can be differentiated based on akinete shape.

Order : Nostocales Family: Rivulariaceae Genus : Calothrix sp. Calothrix filaments are wider at the base, with elongated, tapered, and hair-like apical regions. The vegetative cells are usually barrel-shaped, cylindrical, or slender and elongated, but are sometimes enlarged. Firm mucous sheaths are always present, and are clear, yellow, or brown in color. Occasionally, false branching forms if the trichomes separate and then both continue to grow inside the original sheath. Calothrix usually has ellipsoidal or spherical heterocysts located at the base of the filaments or near points of false branching.

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