Algae work book 2015

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1. Fresh water algae.
(i) Stagnant fresh water algae e.g. Spirogyra, Zygnema, Chara, Rivzdaria.
(ii) Running fresh water algae e.g. Ulothrix. (iii)Epipelic algae (attached to sand or mud at the bottom of water
body ego Chara, Nitella. '
2. Sea water algae. e.g. Fucus, Ectocarpus, Polysiphonia.
3. Epiphytic algae. (on body of other plants) e.g. Bulbochaete, Oedogonium.
4. Endophytic algae. (inside the body of plants) e.g. Anabaena in coralloid roots of Cycas, Nostoc in Anthoceros
thallus, Coleochaete nitellarum inside Nitella and Endoderma cladoporae inside Cladophora.
5. Epizoic alge. (on the body of animals) e.g. Cla.dophora crispata on shells of molluscs and Oscillatoria and
Dermatophyton on bodies of turtles.
6. Endozoic algae. (inside the body of animals) e.g. Zoochlorella in Hydra. The blue green algae which grow
endozoically in protozoans are called as cyanellae.
7. Parasitic algae. e.g. Cephaleuros virescence (green algae) on leaves of tea and coffee. Harveyella (red algae) is
parasitic on other red algae (Gracilaria). Polysiphionia fastigeata (red algae) is parasitic upon Ascophyllum nadosum.
Rhodochytrium is parasitic upon mango.
8. Cryophytic algae. Some algae flourish well at low temperatures in ice and snow. e.g. Chlamydomonas or
Haematococcus nivalis on snow or ice.
Cryophytic algae imparting red colour to snow. Red snow balls in arctic region are caused by Chlamydomonas
(Haematocoeocus nivalis). Black snow is caused by Rhapidonema, purple brown snow by Ancylonema nordenskioldii and
Mesotaenium sp, blue snow by Daetyloeoecopases and yellow snow by Chlamydomonas flavovirens and Cystococcus
nivicola due to presence of specific pigments in their cells
9. Thermal algae. Some algae are adopted to grow in very hot waters (upto 85"C) e.g. Syneehococeus, Scytonema,
Oscillatoria, Confera thermalis.
10. Terrestrial algae. Some algae grow well in moist, well aerated and fertile soils and these are called
edaphophytes e.g. Vaeucheria, Nostoc, Fritsehiella.
Thallus organisation in Algae Thallus of algae may be.
(1) Unicellular. (a) Motile e.g. Chlamydomonas. (b) Non-motile e.g. Chlorella.
(2) Multicellular. Thallus may be : (i) Colonial. Many cells grow together to form colony. e.g. Volvox, Gonium,
Hydrodictyon, Scenedesmus.A colony with difinite number of cells is called coenobium.
(ii) Filamentous. Thallus is thread like and may be: (a) Unbranched. e.g. Ulothrix, Spirogyra, Oedogonium.
(b) Branched. e.g. Cladophora.
(c) Heterotrichous. It is most advanced. In this, thallus consists of two types of filaments prostrate a nd projecting
or erect e.g. Fritschiella, Stigeocolonium. It has been believed that land plants have been evolved from
heterotrichous algae.
(d) Siphonaceous. e.g. Vaucheria.
(e) Pseudoparenchymatous. e.g. Polysiphonia (polyaxial), Batrachospermum (monoaxial).
(f) Parenchymatous. e.g. Macrocystis (largest algae), Laminaria, Sargassum.
(g) Palm like e.g. Postelsia (sea palm).
Nutrition in Algae. Mostly algae are autorophic (Holophytic ).
The heterotrophic algae may be phagocytic or holozoic or may be osmotrophic (absorb nutrients in soluble form)
or may be parasitic (obtain food from living host) ..
Economic Importance of Green Algae
Green Algae are mostly fresh water and hardly 10% are marine. They are primary producers of food in aquatic
habitat. Some useful green Algae are:
1. Ulva (sea lettuce), Caulerpa, Enteromorpha, Chlorella, Spirogyra, Oedogonium have food value.
Codium and Ulva (sea lettuce) is used as salad or vegetable in european countries after drying and salting. It is used as
food for pigs in Singapore. Chlorella pyrenoidosa (called space alga) is used by exobiologists/astronauts for food, oxygen
and disposal of CO2 and organic waste in prolonged space flight. It decomposes urine and faeces to get nitrogen for
protein synthesis. It has a short life cycle and can be grown quickly. It has proteins (upto 50%), amino acids (like lysine
and threonine), minerals (Ca, Fe, P, Zn), fats (20%), carbohydrates (20%), Vit A, B1' B2' B12' C and E . It is a source of SCP
(single cell protein) and is cultivated in Germany, Taiwan, USA and Japan. The protein of Chlorella is superior to cereals
as it contains all essential amino acids. Its nutritional value is equal to Soybean and Spinach. Scenedesmus is eaten in
2. Chlorella, Chlamydomonas, Scenedesmus grow in sewage oxidation tanks and produce O2, This oxygen helps
aerobic bacteria to decompose sewage. Such tanks show algae-bacterial symbiosis.
3. Chlorella pyrenoidosa is a good source of hydrocarbons for using as fuel.
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4. Chlorella yields an antibiotic chlorellin which is effective against bacteria.
5. Chiarella and Scenedesmus have been used widely for studying photosynthesis.
7. Acetabularia (umbrella alga) is the largest unicellular marine alga, 10 em in length with a cap, stalk and rhizoid
containing nucleus. It was used by Hammerling for his grafting experiment to prove the role of nucleus in heredity.
8. Chara, Nitella have larvicidal properties and kill mosquito larvae. Chara being rich in calcium salts is used to
correct (reclaim) acidity of soil.
9. Cephaleuros virescence is a parasite and causes red rust of tea leaves in tea gardens. C. coffea attacks coffee leaves.
It is red due to haematochrome.
11. Caulerpa is a coenocytic alga. It shows heterotrichous habit and is edible.
12. Monostroma is source of Aonori food in Japan.
13. Spirogyra is used to produce lens paper in Japan.
14. Spirogyra with Diatoms and Oscil/atoria block water filters.
Economic Importance of Brown Algae.
Economically, brown algae are fairly important and provide food, iodine, algin etc. Laminaria, Alaria, Nereocystis,
Macrocystis, Fueus, Sargassum are used as food, manure and fodder. Laminaria yields a food product rich in
carbohydrate (upto 57%) called kombu and similarly Alaria yields a product called sarumen in Japan.
Algin is a phycocolloid extracted from middle lamella cell walls of Laminaria, A/aria, Maerocystis, Lessonia, Fucus,
Sargassum, Nereocystis and Turbinaria. In India, it is obtained from Sargassum.
Alginates are salts of alginic acid and are used in flame proof plastics, security glass, gauze and surgical threads,
shaving creams, tooth paste, cosmetic creams and compacts, shampoos, sauces, sizing textiles, dentures, antibiotic
capsules and for providing smooth glazed surface to paper and ceramic. It prevents ice formation in ice cream and
brush marks in paints and polishes.
. Kelps like Fucus and Laminaria are rich source of iodine. 25% of total iodine is obtained from kelps and also
contain bromine, Cu, Zinc, Fe, Boron, Mn, Mo etc. while potash is abundant in Macrocystis. Because of having iodine
the dried kelps are used to treat goiter.
Some brown algae like Ectocarpus grow on the hulls of the ships and boats and cause corrosion and shorten the
life of vessels. The thick growth of these kelps produces resistance in the movement of vessels and thereby reduce
their speed.
Economic Importance of Red Algae
1. Red algae provide food, fodder and commerical products. Porphyra tenera (Laver) is rich in proteins (30-35%), carbohydrats
(40-45%), and vit A, S, E and C. It has minimum number of chromosomes (n =2). It is the source of Amanori or also called
Asakusa Nori (Nori) and is eaten with rice in Japan, China and pacific coastal area. This alga in mass scale is cultivated in Japan
and Phillipines near the sea shores in shallow water.
2. Chondrus (Irish moss) is most widely used sea weed in Europe. It is cultivated in Canada and is edible. Mucilage is also
extracted from it which is used in shampoos, shoe polish and creams.
Carrageenin is a sulphated polysaccharide obtained from cell wall of Chondrus crisp us and Gigartina and is used in
confectionary, bakery, jelly, creams, as clearing agent in liquors (Beer) and leather finishing; as emulsifier in chocolates,
icecreams. sauces, tooth pastes and paints and cosmetics. It gives creaminess in chocolate drinks. Carrageenin is used as
coagulating agent.
3. Funori is a glue used as adhesive and in sizing textiles, papers etc. It is obtained from Gloiopeltis.
It is also called funoran (funori of Japan) and is used in hair curling as well as blood anticoagulant.
4. Agar (agar agar)/Japan Isinglass/Japanese gelatin is a sulphated non nitrogenous, tasteless, odourless gelatinous
phycocolloid (mucopolysaccharide) obtained from middle lamella of cell wall of marine/coastal red algae like Gracilaria,
Gelidium, Gigartina, Pteroc/adia, Phyllophora, Ceramium, Furcellaria, Ge/idiella and Chondrus. These algae are called
agarophytes. China is the largest producer of agar. It is a polymer of mainly 0 and L-ga/actose with sulphate esterification
after every tenth galactose unit. It was discovered by Lady Hesse and used by Robert Koch to solidify culture medium. About
1.5 to 2% agar is added in culture medium to make it solid. It forms gel at concetration as low as 0.5%. It starts liquifying
(melting) at 92°C and melts completely in between 96-98°C and remains molten upto 42.6°C. At temperature below 42°C, it
starts solidifying and solidifies at 37"C completely. This property of agar has made it most useful solidifying agent because
microbes grow well at temperature between 25 to 37"C on this solid medium. This agar has no nutritional value and does not
react with any other nutrient in the culture medium and moreover, it is not digested or liquified by microbes. It is obtained
from Gelidium amnasii in Japan; Gracilaria confervoides in Australia and pterocladia lucida in Newzealand. In India it is
obtained from a number of agarophytes, particularly, Gelidiella. Furcellaran is Danish agar obtained from Furcellaria. Agar has
two components viz. agarose and agaropectin. Agarose is polymer of D and L galactose and swells up in hot water and gives
gel like property to agar. Agaropectin is sulphonated polysaccharide and gives viscosity to agar medium. Agar swells up
absorbing water as much as 20 times its weight. Agar is also used as laxative stabilizer or thickener in preparing jams, jellies,
creams, puddings, baby food, ice cream, bakery products. It is also employed as emulsifier in canning of fishes and paper
industries and as laxative in drug industry.
5. Phyllophora is the source of Iodine of commerce in Russia. Rhodomela and Polysiphonia are used to yield bromine of
commercial importance.
6. Rhodymenia palmata (Sheep's weed) is used as fodder for sheep in France. It is also used as a salty confection called dulse
and is chewed like tobacco in Scotland.
7. Corallina has vermifuge properties; agar is laxative. Polysiphonia is antibacterial.
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