PDF CYANOPHYTA - Narajole Raj College

(1)

BOTANY: SEM – I, PAPER

Contents: 1. Introduction 2. Characteristics

5. Morphology 6 . C e l l s t r u c t u r e 7 . Economic Importance.

1. Introduction to Cyanophyta:

It is a primitive group of algae, consists of 150 genera division is represented by 98 genera

(Cyanophyceae) are commonly known

because of the presence of a dominant pigment c other pigments like chlorophyll

xanthophylls are also present. The members of this clas prokaryotes.

2. Important characteristic Features

a. Nucleus is of prokaryotic nature i.e., devoid of nuclear membrane and b. Absence of well-organised cell organelles,

c. Pigments are distributed throughout the

Depending on the above prokaryotic characteristics many microbiologists consider the members Cyanophyceae as bacteria. Based

placed both Cyanophyta and bacteria

green algae have also been named as cyanobacteria.

Important Characteristics of Cyanophyceae:

The important characteristics of the division are as follows:

1. The individual cells are prokaryotic

I, PAPER-C1T: PHYCOLOGY AND MICROBIOLOGY, UNIT CYANOPHYTA

CYANOPHYTA

1. Introduction 2. Characteristics features 3. Occurrence 4. Thallus 6 . C e l l s t r u c t u r e 7 . Reproduction 8. Origin

Introduction to Cyanophyta:

group of algae, consists of 150 genera and about 2,500 species. In genera and about 833 species. Members of the class

known as blue green algae. The name blue green because of the presence of a dominant pigment c-phycocyanin, the blue green pigment.

chlorophyll a (green), c-phycoerythrin (red), β-carotene ylls are also present. The members of this class are the simplest

Important characteristic Features:

Nucleus is of prokaryotic nature i.e., devoid of nuclear membrane and nucleolus, organised cell organelles, and

Pigments are distributed throughout the chromoplasm (the outer part of protoplasm).

Depending on the above prokaryotic characteristics many microbiologists consider the members ophyceae as bacteria. Based on prokaryotic cell structure like bacteria,

bacteria under a common phylum Prokaryota. Cyanophyta green algae have also been named as cyanobacteria.

Important Characteristics of Cyanophyceae:

The important characteristics of the division are as follows:

prokaryotic in nature. The nucleus is incipient type

PHYCOLOGY AND MICROBIOLOGY, UNIT-5:

Thallus Organisation 9 . Affinities 10.

and about 2,500 species. In India, the class Myxophyceae green algae is given phycocyanin, the blue green pigment. In addition, carotene and different living autotrophic

nucleolus,

protoplasm).

Depending on the above prokaryotic characteristics many microbiologists consider the members of Christensen (1962) Cyanophyta or blue

type and they lack

(2)

BOTANY: SEM – I, PAPER membrane bound organelles.

2. Both vegetative and reproductive cells are 3. Cell wall is made up of microfibrils

composed of mucopeptide, along with carbohydrates, amino acids and fatty acids.

4. Locomotion is generally absent, but when occurs, it is of gliding or jerky 5. The principal pigments are chlorophylls a (green), c

(red). In addition, other pigments like myxoxanthophyll are also present.

6. Membrane bound chromatophore are absent. Pigments are found embedded in 7. The reserve foods are cyanophycean starch

8. Many filamentous members possess specialized cells of disputed function (supposed to be centre of N2 fixation) known as heterocysts.

9. Reproduction takes place by

place by cell division, fragmentation etc. Asexual reproduction takes place akinetes, nannospores etc.

10. Sexual reproduction is completely absent. Genetic recombination is reported in 2

3. Occurrence of Cyanophyceae:

Members of Cyanophyceae are available in different habitats. Most of the species are fresh (e.g., Oscillatoria, Rivularia), a

species of Oscillatoria and Nostoc are grown on terrestrial habit Species of some members like

(Bryophyta) and in leaves of (Gymnosperm).

Both vegetative and reproductive cells are non-flagellate.

microfibrils and is differentiated into four (4) layers.

omposed of mucopeptide, along with carbohydrates, amino acids and fatty acids.

Locomotion is generally absent, but when occurs, it is of gliding or jerky type.

The principal pigments are chlorophylls a (green), c-phycocyanin (blue) and c

ed). In addition, other pigments like β-carotene and different xanthophylls like myxoxanthin

Membrane bound chromatophore are absent. Pigments are found embedded in The reserve foods are cyanophycean starch and cyanophycean granules (protein).

Many filamentous members possess specialized cells of disputed function (supposed to be fixation) known as heterocysts.

by vegetative and asexual methods. Vegetative

cell division, fragmentation etc. Asexual reproduction takes place by endospores,

Sexual reproduction is completely absent. Genetic recombination is reported in 2

Occurrence of Cyanophyceae:

Members of Cyanophyceae are available in different habitats. Most of the species are fresh few are marine (e.g., Trichodesmium, Darmocarpa), species of Oscillatoria and Nostoc are grown on terrestrial habitat.

like Anabaena grow as endophytes in thallus of Azolla (Pteridophyta) and Nostoc in the

layers. The cell wall

type.

phycocyanin (blue) and c-phycoerythrin carotene and different xanthophylls like myxoxanthin and

Membrane bound chromatophore are absent. Pigments are found embedded in thylakoids.

(protein).

Many filamentous members possess specialized cells of disputed function (supposed to be the

reproduction takes endospores, exospores,

Sexual reproduction is completely absent. Genetic recombination is reported in 2 cases.

Members of Cyanophyceae are available in different habitats. Most of the species are fresh water Darmocarpa), and some

thallus of Anthoceros the root of Cycas

(3)

Species of Nostoc, Scytonema, Gloeocapsa, fungi and form lichen. Some members and increase soil fertility.

4. Thallus Organisation in Cyanophyceae:

Plants of this group show much variation in their t The thallus may be of unicellular or colonial forms:

1. Unicellular Form:

In unicellular form, the cells may be oval or spherical. Common members are Gloeocapsa (Fig.

Chroococcus and Synechococcus.

2. Colonial Form:

In most of the members the cells after division remain attached by their cell wall or remain in a common gelatinous matrix, called a colony.

The colonies may be of two types:

a. Non- filamentous, and b. Filamentous.

Gloeocapsa, and Chroococcus grow symbiotically members like Nostoc, Anabaena etc. can fix atmospheric

Thallus Organisation in Cyanophyceae:

Plants of this group show much variation in their thallus organisation.

The thallus may be of unicellular or colonial forms:

In unicellular form, the cells may be oval or spherical. Common members are Gloeocapsa (Fig.

Chroococcus and Synechococcus.

ers the cells after division remain attached by their cell wall or remain in a common gelatinous matrix, called a colony.

The colonies may be of two types:

symbiotically with different atmospheric nitrogen

In unicellular form, the cells may be oval or spherical. Common members are Gloeocapsa (Fig. 1),

ers the cells after division remain attached by their cell wall or remain together

(4)

BOTANY: SEM – I, PAPER 1.

(5)

BOTANY: SEM – I, PAPER a. Non-Filamentous Type:

The cells of this type divide either (Gomphosphaera,Coelosphaerum), cub irregular (Microcystis, Fig. 1. B) colony.

b. Filamentous Type:

By the repeated cell division in e.g., Oscillatoria (Fig. 1. D),

mucilaginous sheath is called a filament. The filament may contain single trichome Lyngbya) or several trichomes (Hydrocoleus, Microcoleus, Fig.

unbranched (Oscillatoria, Lyngbya), branched (Mastigocladus limilosus, branched (Scytonema, Fig. 1.K and Tolypothrix).

5. Morphology of Cyanobacteria:

Cyanobacteria may be unicellular, colonial or filamentous. Each filament consists of a sheath of mucilage and one or more cellular strands called trichomes.

Single trichome filaments may further be of two types, homocystous (= undiffer

Oscillatoria) and heterocystous (= differentiated, having heterocysts, e.g., Nostoc). Spirulina a spirally coiled filament. Colonies develop in some cases, e.g., Nostoc.

Flagella are absent but gliding movements Oscillatoria has been given to a

oscillating movements of its anterior region.

6. Cell Structure of Cyanobacteria:

Cyanobacterial cells are larger and mo

either alternately or in three planes, thereby they (Gomphosphaera,Coelosphaerum), cubical (Eucapsis alpine, Fig. 1. C), squarish

colony.

one plane, single row of cells are formed, known Spirulina, Arthosporia etc. The trichome when mucilaginous sheath is called a filament. The filament may contain single trichome

Lyngbya) or several trichomes (Hydrocoleus, Microcoleus, Fig. 1.E). The trichomes may be unbranched (Oscillatoria, Lyngbya), branched (Mastigocladus limilosus, Fig. 1.

K and Tolypothrix).

Cyanobacteria:

Cyanobacteria may be unicellular, colonial or filamentous. Each filament consists of a sheath of mucilage and one or more cellular strands called trichomes.

Single trichome filaments may further be of two types, homocystous (= undiffer

Oscillatoria) and heterocystous (= differentiated, having heterocysts, e.g., Nostoc). Spirulina a spirally coiled filament. Colonies develop in some cases, e.g., Nostoc.

movements are known in a number of cyanobacteria.

a common blue green alga on the basis of oscillating movements of its anterior region.

Cell Structure of Cyanobacteria:

Cyanobacterial cells are larger and more elaborate than bacteria. Cell structure is

they form spherical (Merismopedia) or

known as trichome.

when covered by mucilaginous sheath is called a filament. The filament may contain single trichome (Oscillatoria, The trichomes may be Fig. 1.J) and falsely

Cyanobacteria may be unicellular, colonial or filamentous. Each filament consists of a sheath of

Single trichome filaments may further be of two types, homocystous (= undifferentiated, e.g., Oscillatoria) and heterocystous (= differentiated, having heterocysts, e.g., Nostoc). Spirulina has

cyanobacteria. The name pendulum like

re elaborate than bacteria. Cell structure is typically

(6)

BOTANY: SEM – I, PAPER prokaryotic— one envelope organisation and absence of membrane bound bodies, plastids, lysosomes, sap vacuoles.

The cell wall is four layered with peptidoglycan present in the second layer. The outer part of protoplast contains a number of

thylakoids lie freely in the cytoplasm.

xanthophyll’s. Chlorophyll b is absent.

organisation with peptidogly can wall, naked DNA,

bound structures like endoplasmic reticulum, mitochondria, tids, lysosomes, sap vacuoles.

The cell wall is four layered with peptidoglycan present in the second layer. The outer part of of photosynthetic thylakoids. It is called chromoplasm.

cytoplasm. Their membranes contain chlorophyll a, xanthophyll’s. Chlorophyll b is absent.

70S ribosomes mitochondria, Golgi

The cell wall is four layered with peptidoglycan present in the second layer. The outer part of the chromoplasm. The a, carotenes and

(7)

BOTANY: SEM – I, PAPER Attached to the thylakoid membranes possess accessory photosynthetic

types— phycocyanin (blue), allophycocyanin (blue) and phycoerythrin (red).

Differential formation of phycobilins absorbing maximum amount of solar

green. They may appear purplish, violet, brownish, etc.

Instead of typical vacuoles or sap vacuoles, gas vacuoles or pseudo vacuole consists of a number of submicroscopi

as light screen; provide buoyancy regulating mechanism and pneumatic strength.

A naked, circular, double stranded DNA lies coiled generally in the central part of the known as centroplasm. The coiled

organisms. It is often called nucleoid.

occur in addition to nucleoid.

They are known as plasmids or transposons.

group of coiled membranes often

as lamella some. Four types of inclusions starch), β-granules (lipid droplets), vol carboxylase).

Heterocyst of Cyanobacteria:

It is a large-sized pale coloured thick

position in filamentous cyanobacteria, e.g., Nosto

permeable to nitrogen. Mucilage sheath is absent. Photosystem II is absent.

membranes are small granules known as phycobilisomes.

pigments known as phycobilins. The phycobilins phycocyanin (blue), allophycocyanin (blue) and phycoerythrin (red).

phycobilins produces specific colouration which solar radiation. Therefore, cyanobacteria are not green. They may appear purplish, violet, brownish, etc.

Instead of typical vacuoles or sap vacuoles, gas vacuoles or pseudo-vacuoles are found. Each submicroscopic units called gas vesicles. Gas vacuoles as light screen; provide buoyancy regulating mechanism and pneumatic strength.

A naked, circular, double stranded DNA lies coiled generally in the central part of the coiled up DNA is equivalent to a single chromosome

nucleoid. Like bacteria, small circular DNA segments

transposons. 70S ribosomes occur here and there.

attaches the plasma membrane with the nucleoid.

inclusions occur in the cells. They are α-granules granules (lipid droplets), volutin granules and polyhedral bodies (ribulose

thick-walled cell which occurs in terminal, intercalary position in filamentous cyanobacteria, e.g., Nostoc. The thick wall is impermeable to oxygen permeable to nitrogen. Mucilage sheath is absent. Photosystem II is absent.

phycobilisomes. The latter phycobilins are of three

which is adapted to not always blue

vacuoles are found. Each gas vacuoles function

A naked, circular, double stranded DNA lies coiled generally in the central part of the cytoplasm chromosome of higher segments may also

there. Semicircular nucleoid. It is known (cyanophycean utin granules and polyhedral bodies (ribulose biphosphate

intercalary or lateral c. The thick wall is impermeable to oxygen but

(8)

BOTANY: SEM – I, PAPER Thylakoids lack phycobilisomes.

photophosphorylation occurs. Heterocyst is dependen

cells. It has enzyme nitrogenase. Heterocyst is specialised to perform nitrogen fixation.

7. Reproduction in Cyanophyceae:

The blue green algae (Cyanophyceae) reproduce by both vegetative and asexual means. Sexu reproduction is absent.

The vegetative reproduction performs through fission (Synechococcus), Cylindrospermum muscicola), hormogonia formation (Oscillatoria, (Westiella lanosa), planococci and P

During asexual reproduction various

(Anabaena sphaerica, Gloeotrichia natans, Calothrix fusca), endospores (Dermocarpa), (Chamaesiphon) and nannocyte (Microcystis) (Fig. 3.

phycobilisomes. Therefore, photosynthesis is absent photophosphorylation occurs. Heterocyst is dependent for its nourishment on adjacent cells. It has enzyme nitrogenase. Heterocyst is specialised to perform nitrogen fixation.

Reproduction in Cyanophyceae:

The blue green algae (Cyanophyceae) reproduce by both vegetative and asexual means. Sexu

The vegetative reproduction performs through fission (Synechococcus), fragmentation Cylindrospermum muscicola), hormogonia formation (Oscillatoria, Nostoc), (Westiella lanosa), planococci and Palmelloid stage.

various types of asexual spores are formed. These (Anabaena sphaerica, Gloeotrichia natans, Calothrix fusca), endospores (Dermocarpa),

nnocyte (Microcystis) (Fig. 3.).

absent but cyclic t for its nourishment on adjacent vegetative cells. It has enzyme nitrogenase. Heterocyst is specialised to perform nitrogen fixation.

The blue green algae (Cyanophyceae) reproduce by both vegetative and asexual means. Sexual

fragmentation (Oscillatoria, Nostoc), hormospores

These are akinetes (Anabaena sphaerica, Gloeotrichia natans, Calothrix fusca), endospores (Dermocarpa), exospores

(9)

Gaidukov phenomenon or complementary chromatic adaptation:

The efficiency to change the pigment composition, to absorb maximum light for photosynthesis, with the variation of the incident light is called complementary chromatic adaptation.

members of Cyanophyceae have the capacity to change their colour in relation to the incident light. Due to variation of the wavelength of incident light they can change composition.

It may appear blue green in yellow (1903) first invented the phenomenon phenomenon.

Gaidukov phenomenon or complementary chromatic adaptation:

The efficiency to change the pigment composition, to absorb maximum light for photosynthesis, with the variation of the incident light is called complementary chromatic adaptation.

bers of Cyanophyceae have the capacity to change their colour in relation to the incident light. Due to variation of the wavelength of incident light they can change

yellow light, green in red light and reddish in green phenomenon and according to his name it is also known

The efficiency to change the pigment composition, to absorb maximum light for photosynthesis, with the variation of the incident light is called complementary chromatic adaptation. Many bers of Cyanophyceae have the capacity to change their colour in relation to the wave length of incident light. Due to variation of the wavelength of incident light they can change their pigment

green light. Gaidukov known as Gaidukov

(10)

BOTANY: SEM – I, PAPER 8. Origin of Cyanophyceae:

This group is considered to be the most primitive because of the presence of features.

These are:

a. Presence of unorganised nucleus, b. Absence of chromatophores, c. Absence of flagella, and d. Lack of sexual reproduction.

They are found in all habitats where records indicate that they have originated known. Absence of flagella and

have originated from unicellular aflagellate cells.

Presence of most of the members in terrestrial habitat leads to believe by most of the that the Cyanophyceae have originated from terrestrial members.

9. Affinities of Cyanophyceae:

The members of Cyanophyceae show some relationship with both bacteria Similarities of Cyanophyceae with Bacteria:

1. Cell structure is prokaryotic membrane bound organelle.

2. The capsule of bacteria (if present) and mucilaginous sheath of blue green al up of fine fibrils.

Origin of Cyanophyceae:

This group is considered to be the most primitive because of the presence of

nucleus,

where life is possible and distributed throughout originated in early Pre-Cambrian period. But their

the prokaryotic nature of cells lead to believe have originated from unicellular aflagellate cells.

e of most of the members in terrestrial habitat leads to believe by most of the that the Cyanophyceae have originated from terrestrial members.

Affinities of Cyanophyceae:

The members of Cyanophyceae show some relationship with both bacteria and Rhodophyceae.

Similarities of Cyanophyceae with Bacteria:

prokaryotic in both the group, having unorganised nucleus

The capsule of bacteria (if present) and mucilaginous sheath of blue green al

This group is considered to be the most primitive because of the presence of some important

throughout the world. Fossil their ancestry is not believe that possibly they

e of most of the members in terrestrial habitat leads to believe by most of the investigators

and Rhodophyceae.

nucleus and devoid of

The capsule of bacteria (if present) and mucilaginous sheath of blue green algal cells are made

(11)

BOTANY: SEM – I, PAPER 3. Cell wall composed of mucopeptide 4. Oscillatoria (blue green alga) shape and movement.

5. Both are sensitive to antibiotics.

6. Both the groups show simil metabolism.

7. Absence of sexual reproduction.

8. Genetic recombination has been showing similarity with bacteria.

Similarities of Cyanophyceae with Rhodophyceae (Red Algae):

1. Both the groups resemble in the absence of motile 2. The Cyanophycean pigments,

similar to the Rhodophycean pigment r 3. Stignema and some other

relationship by having similar structures as found in the members of Rhodophyceae.

10. Economic Importance of Cyanophyceae:

The Cyanophycean members show both beneficial and harmful a Beneficial Activities:

1. Nostoc commune is boiled and used as soup in

2. Few species of Nostoc, Anabaena, Scytonema form a thick substratum over the soil resulting reclamation of land.

Cell wall composed of mucopeptide (murein).

alga) shows similarity with Beggiatoa (sulphur bacterium),

antibiotics.

Both the groups show similarity in many metabolic processes like nitrogen and

reproduction.

been reported in Anacystis nidulans, a member

with Rhodophyceae (Red Algae):

Both the groups resemble in the absence of motile cells.

pigments, c-phycocyanin (blue) and c-phycoerythrin (red) similar to the Rhodophycean pigment r-phycocyanin and r-phycoerythrin.

members of Cyanophyceae have pit connections, relationship by having similar structures as found in the members of Rhodophyceae.

Economic Importance of Cyanophyceae:

The Cyanophycean members show both beneficial and harmful activities.

Nostoc commune is boiled and used as soup in China.

Few species of Nostoc, Anabaena, Scytonema form a thick substratum over the soil resulting

bacterium), both in

arity in many metabolic processes like nitrogen and sulphur

member of Cyanophyceae,

(red) are chemically

connections, and show

Few species of Nostoc, Anabaena, Scytonema form a thick substratum over the soil resulting a

(12)

3. About twenty two (22) filamentous members of Cyanophyc Anabinopsis, Calothrix, Scytonema

compounds. These compounds are yield.

All the above members have heterocyst. But certain non are able to fix atmospheric nitrogen in anaerobic condition.

Harmful Activities:

1. Some members of Cyanophyceae avoided by spraying CuSO4 and sodium arcenate.

2. Some members like Microcystis, deficient water. Continuous respiration

photosynthesis does not take place) causes the depletion of O

of both animals and other submerged plants takes place due to suffocation.

3. Blue green algae contaminate

make it unhygienic for human being and cause several diseases.

Different diseases like gastric troubles may appear by drinking the water contaminated with Anabaena.

REFERENCES:

1. Studies in Botany by Mitra, Mitra and Chowdhury (2005) 7 2. Botany for Degree Students Part

3. https://www.biologydiscussion.com/algae/cyanophyceae classification/46739

This information, including the figures, are collected fr solely for academic purpose.

About twenty two (22) filamentous members of Cyanophyceae like Nostoc, Anabaena, Scytonema etc. can fix atmospheric nitrogen and

further absorbed by the plant for their metabolic

bove members have heterocyst. But certain non-heterocystous members like Plectonema are able to fix atmospheric nitrogen in anaerobic condition.

Cyanophyceae cause damage of building plasters, stones and sodium arcenate.

Microcystis, Anabaena, form water blooms and can respiration by submerged plants and animals during take place) causes the depletion of O2 to almost zero level. At that of both animals and other submerged plants takes place due to suffocation.

contaminate the water of reservoirs. They develop a foul make it unhygienic for human being and cause several diseases.

Different diseases like gastric troubles may appear by drinking the water contaminated with

Studies in Botany by Mitra, Mitra and Chowdhury (2005) 7^th Edition, Vol. I.

Botany for Degree Students Part-I ALGAE by Vashishta, Sinha and Singh (2002) https://www.biologydiscussion.com/algae/cyanophyceae-characteristics-occurrence

This information, including the figures, are collected from the above references and will be used

Anabaena, Aulosira, and form nitrogenous

activity and increase

heterocystous members like Plectonema boryanum

stones etc. It can be

can grow well in O2

during night time (when that condition mortality

odour in water and

Different diseases like gastric troubles may appear by drinking the water contaminated with Microcystis and

ition, Vol. I.

by Vashishta, Sinha and Singh (2002).

occurrence-and-

om the above references and will be used