Ecological and economic importance of algae

1. ECOLOGICAL AND
ECONOMIC IMPORTANCE
OF ALGAE
Submitted by,
Silpa Selvaraj
I Msc Botany
St Teresa's college
Ernakulam

2. ALGAE AS FOOD
More than 100 species, mostly of Phaeophyceae and Rhodophyceae, are used
as food by man in different parts of the world.A few species of Chlorophyceae
are also used as human food because of the presence of minerals, vitamins,
carbohydrates and proteins, either in their cell wall or in their cytoplasm. Some of
the important genera with their uses are mentioned below.

3. Among Phaeophyceae, some of the genera used as human food are
Alaria, Laminaria, Sargassum, Durvillea, Undaria, Eisenia, Ecklonia and
Pelvetia.
● In Japan, the food prepared from Laminaria is called kombu, and
the food from Alaria is called sarumen.
● In South America, Durvillea is collected, dried, salted and sold as
Cachiyago.
● The contents of food value of brown algae include 6.l5% protein
(with 17 amino acids), 1.56% fat and 57.04% carbohydrates.
● Many minerals along with carotene, thiamin and subflavine also
found in brown algae.
KOMBU
Alaria
Laminaria Eisenia Durvillea

4. Among Rhodophyceae, the important genera used as food are Porphyra,
Palmaria, Chondrus,Gigartina, Gracilaria, Gelidium, Eucheuma and
Rhodymenia.
● Porphyra is most important red alga used as human food. It is
variously “called nori in Japan, laver in England and United States,
sloke in Scotland, and luche in Southern Chile” Porphyra
preparations are very rich in vitamins B and C.
● In Japan alone, 29.5 million kg of Porphyra per year is used as food.
● Palmaria is also eaten under different trade names in different
countries, such as ‘ dulse’ in Canada, ‘ sol’ in Iceland and ‘ dillisk’ in
Ireland.
● Chondrus crispus is commonly called ‘ Irish moss’ and used in ice-
creams and various other foods.
● Gigartina stellata is used for the production of mucilage, which
contains galactose sulphuric acid.
● Rhodymenia palmata is used as a common food ‘ dulse’ by fishermen.
● Glycerol, sorbitol and dulcitol are some of the carbohydrates found
in red algae.
● Floridean starch, produced from Rhodophyceae, is a glucose.
Nori
Palmaria

5. Dulse Irish moss Gracilaria
Gelidium Rhodymenia
Porphyra

6. Among Chlorophyceae, the important algae used as
food are Monostroma, Ulva, Codium, Chlorella,
Caulerpa and Enteromorpha.
● Monostroma is used as a common food “
aonori” in Japan.
● Ulva is dried, salted and sold as ‘ cachiyugo’
similar to Durvillea. It is also used as salad.
● Codium is used as salad in Japan and many
other countries.
● Chlorella is well-known for its high percentage of
lipids and proteins. The Chlorella protein has all
essential amino acids, and therefore it is used as
a food in space-fl ights. Although Chlorella can
be a good substitute for food in crisis, its culture
is very expensive. According to Thacker and
Babcock (1957), production of Chlorella is not
economic. As it has an antibiotic, chlorellin, its
use as a food is also discouraged.
Aonori
Ulva
Chlorella
Codium

7. ● Among the blue-green algae, Nostoc commune is
used as a food called ‘ yuyucho’ in China, Java,
etc.
● Spirulina has a protein content in excess of 60%
and is extensively cultivated (Shelef and Soeder,
1980).
● Diatoms are also used as food in some parts of
the world.
■Seaweeds are an excellent source of vitamins
including vitamin C at levels equivalent to citrus fruits
and vitamins A, D, B1, B12, riboflavin, niacin,
pantothenic acid and folic acid. seaweeds also provide
all the required trace elements for human nutrition
Spirulina
Diatom
Nostoc

8. ALGAE AS FODDER
Algae constitute a source of “permanent food” for many animals,
including foxes, deer, rabbits and bears. These include mainly the
members of Phaeophyceae, Rhodophyceae and some green
algae.
1. Laminaria, Sargassurn, Fucus and Ascophyllum are used as
fodder in many areas of the UK and Japan.
2Macrocystis is used for cattle-feed because it is rich in vitamins A
and E.
3.Hens, which feed on Ascophyllum-meal and Fucus meal, produce
eggs with increased iodine content.
4. Seaweed-meals also increase the butter-fat content of the milk in
feeding cattle.
5. A fish, named Tilapia, uses only the members of Cyanophyceae
and Chlorophyceae as its food.
Fucus
Ascophyllum

9. 6.Many fishes depend for their food only on diatoms.
7. Stock-feed and commercial feed are regularly processed
for many cattles, specially sheep and horses, from species of
Laminaria, Ascophyllum and Fucus.
8.The major food of many fishes , protozoans, crustaceans
and many other aquatic animals is provided by planktonic
algae.
9. Rhodymenia is a common cattle-food in France.
9. In Japan, Pelvetia is used as a cow-feed.
Pelvetia

10. ALGAE AS FERTILIZER
Because of the presence of phosphorus, potassium and some trace
elements, the seaweeds in many coastal regions of the world are used as
fertilizer. They are either mixed with some other organic materials or are
allowed to rot in the field as such.
1.Genera like Lithophyllum, Lithothamnion and Chara are used in the
deficiency of calcium in the field.
2.Fucus is used as a common manure by Irish people.
3Cyanobacteria has been used as a biofertilizer,as Symbiont inside Azolla
into paddy fields since long time.
Some of them are: Tolypothrix tenius, Aulosira fertilissima, Anabaena
oryzae, Anabaenopsis arnoldii, Calothrix confervicola, Nostoc commune,
and Cylindrospermum bengalense.
4. Several brands of liquid fertilizers prepared from seaweed are now
available in the market. They are used in intensive gardening and
greenhouse horticulture
Chara
Lithophyllum

11. ALGAE IN NITROGEN FIXATION
● Some Cyanobacteria have the capacity to fix atmospheric nitrogen.
They include Nostoc,
Anabaena,Aulosira,Calothrix,Nodularia,Scytonema,Oscillatori
a, Cylindrospermum etc
● The nitrogen fixing capacity of heterocystous cyanobacteria is
more in comparison to non heterocystous forms.

12. ALGAE IN MEDICINE
1.An antibiotic, chlorellin, is obtained from Chlorella.
2.Some antibacterial substances, effective against Gram-
positive and Gram-negative bacteria, were also reported from
Ascophyllum nodosum, Rhodomela larix, Laminaria digitata
and some species of Pelvetia and Polysiphonia.
3.An antibiotic, effective against some bacteria, has been
prepared from a diatom Nitzschia palea. It is specially effective
against Escherichia coli.
4.People of maritime nations extensively use seaweeds as
their traditional medicines as vermifuges, ointments and
anaesthetics, as well as for the treatment of cough, gout,
goitre, hypertension, veneral diseases and even for cancer
5.Iodine contents of Laminaria check goitre.
6. “ Tse-ko-Tsoi”, an antihelmitic drug, is prepared from a red
alga Digenia simplex in China
Digenia simplex

13. 7.Fucoidin and sodium laminarin sulphate, obtained from some brown algae, are
used as anticoagulant of blood.
8.Some algae are also used in the treatment of the diseases of kidney, urinary bladder
and lungs.
9.Antiviral compounds, reported to be present in some red algae, are used in treating
herpes viruses.
10. Extracts of Laminaria and Sargassum inhibit the growth of sarcoma and leukaemia
cells in mice.
11.The saxitoxins produced by some dinoflagellates are used in some neurological
disorders and neurobiological researches.
12. Scientists have recently succeded in isolating two important medicinal compounds
from blue-green algae.One was the chemical cytonemin derived from Scytonema, and
was found to be effective against skin cancer. The second was obtained from
Tolypothrix, and is generally administered during heart attacks to improve blood
circulation.

14. ALGAE IN INDUSTRIAL USES
Petroleum industry
● Algal biofuel, or algal oil is an alternative to liquid
fossil fuels that uses algae as its source of energy-
rich oils.
● Also, algae fuels are an alternative to commonly
known biofuel sources, such as corn and
sugarcane.
● When made from seaweed (macroalgae) it can be
known as seaweed fuel or seaweed oil
Eg: Chlorella, Scenedesmus, Chlamydomonas
Scenedesmus

15. Kelp Industry:
The kelp ash from these plants was widely bought by early industrialists for
use in manufacture of soap, glass and alum.
Many species of kelp are used as food for man, especially in the Orient. In
Northern Europe they also serve as food for domestic animals, such as
sheep and cattle.
Fucus and Ascophyllum

16. Algin Industry:
Algin occurs generally throughout the brown algae (Laminaria,
Macrocystis, Sargassum and Fucus) as a cell wall constituent.
● It has remarkable water-absorbing qualities that make it useful in
numerous industries in which a thickening, suspending, stabilizing,
emulsifying, gel-forming, or film-forming colloid is required.
● algin provides ice cream with a smooth texture by preventing the
formation of ice crystals. In automobile polishes it suspends the
abrasive; in paints, the pigments; also in pharmaceuticals, the drugs
and antibiotics. As a stabilizing agent it serves in the processing of
rubber latex

18. Agar Industry:
● The outstanding use of the red algae, however, is in the production of agar.
● This is a dried and bleached gelatinous extract obtained from red algae—
Gelidium nudifrons, G. pusillum, G. robustum, and Gracilaria verrucosa.
● Agar is used extensively in medicine, chiefly as laxative, since it is not
digested and increases greatly in bulk with the absorption of water.
● Agar serves widely as a substitute for gelatin, as an anti-drying agent in
breads and pastry, in improving the slicing quality of cheese, in the
preparation of rapid-setting jellies and desserts, and in the manufacture of
frozen dairy products.
● More important than this medicinal utilization is its use as an essential
ingredient in the preparation of medium for the growth of bacteria and fungi.
As such it is indispensable in bacteriological laboratories, because no
adequate substitute for agar is known.

20. Diatomaceous Earth Industry:
● Most species of Diatoms are marine, and when these minute plants die,
they fall to the sea bottom
● Great deposits of this material, known as diatomaceous earth, are found in
many parts of the world.
● Because diatomaceous earth is inert chemically and has unusual physical
properties, it has become an important and valuable material in industry. It
makes an excellent filtering agent, which is widely used to remove colouring
matters from products as diverse as petrol and sugar.
● It is used in the manufacture of paints and varnishes, of phonograph
records, and as a filler for battery boxes. Because of its hardness, it is used
as an abrasive in scouring and polishing powders.

22. CARRAGEENINS
● Named after an Irish village Carrageenan,
Carrageenin is primarily extracted from red alga
Chondrus crispus and to a lesser extent from Gigartina
spp.
● Two types kappa carrageenins & Lambda
carrageenins.
● Used for making desserts,ice cream,milk
shakes,condensed milk,shampoos, cosmetic
creams,shoe polish etc
● Used in biotechnology as gels to immobilize cells
and enzymes and in pharmaceuticals as an active
excipient in pills and tablets.

23. FUNORI
● It is a sizing agent and glue for textile.
● Prepared from Gloepeltis furcata in Japan.
● It is a cell wall polysaccharide, structurally in
between agar and carrageenin.

25. ALGAE IN BIOLOGICAL RESEARCH
● The cultures of Chlorella, Scenedesmus, Anacystis, etc. are widely used in
many physiological researches, specially in the investigation of
photosynthesis.
● Chlorella has been found very suitable for keeping the air in space vehicles
pure on long interplanetary flights. The stale air in which the carbon dioxide
has been concentrated is fed into a flood-lit container containing a mixture
of water and nutrient chemicals and Chlorella.The alga restores oxygen
into the space vehicle by its photosynthesis.

26. ALGAE IN SEWAGE DISPOSAL
● Sewage consists mainly of domestic and industrial wastes.
● The disposal of this sewage is mainly an aerobic process, and this
oxygenation is facilitated mainly by some algae, e.g. Chlamydomonas,
Chlorella, Euglena, Scenedesmus, etc.
● The aeration of sewage is essential, specially in smaller sewage bodies or
ponds, to avoid unpleasant odour.
ALGAE AS EXPERIMENTAL MATERIAL OR TOOL
● Acetabularia is used to study the material Inheritance of chloroplast genes.
● Chlorella is used to study the path of carbon in photosynthesis.
● Valvonia and Halicystis are used for experiments on the permeability of
membranes.
● Chara and Nitella are well suited to experimental biosystematic
investigations as they are easy to grow.
● Diatoms are used to test the resolution power of microscope lenses.

27. ALGAE AND LAND RECLAMATION
● Several Cyanobacteria like Anabaena, Nostoc and Scytonema have the
capacity to reclaim usar soils.
● They grow on saline usar soils during rainy season and reduce the alkalinity of
the soil ,thereby making it fit for paddy or other cultivation.
ALGAE IN LENS PAPER
Spirogyra is used in the manufacturing of lens paper for cleaning optical articles
in Japan.

28. REFERENCES
● https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.slidesh
are.net/ssmvjunwani/economical-importance-of-algae.
● https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.lscollege
.ac.in/sites/default/files/e-content/Economic%2520imp.
● Sharma, O.P (1986) Series on Diversity of Microbes and Cryptogams: Algae
(Tata McGraw Hill Education Private Limited)
●Ashok Kumar Awasthi (2015) Textbook of Algae (Vikas publishing house pvt
ltd)