Cyanobacteria, also known as blue-green algae, are photosynthetic prokaryotes that can be found in aquatic and moist environments. They contain chlorophyll a and other pigments that give them blue or red colors. Cyanobacteria exist as single cells, colonies, or filaments. Some filamentous forms can move through their environment. Cyanobacteria reproduce through cell division or the formation of resistant spores called akinetes. They can fix atmospheric nitrogen through specialized cells called heterocysts and engage in symbiotic relationships with plants and algae. Cyanobacterial blooms are increasing due to nutrient pollution from human activities and climate change, and some species can produce toxins that are harmful to animals and

1. Cyanobacteria
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
Unicellular
or aggregate
Colony
Filamentous
forms

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

6. e.g.Microcystis sp
2.Colony

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

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

9. Cell structure
• The cell structure is very primitive.
• Each cell is composed of two parts:
a) cell wall
b) protoplast.
The cell wall is composed of 2 layers:
Chromoplast
Central body
Cell wall
The inner layer of which is thin and firm composed of
peptidoglycan.
The outer layer of the wall is thicker and gelatinous known
as the sheath and mainly constituted of pectic compounds.

10. • 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

11. Cyanobacterial cell

12. 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

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

14. 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

15. 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.

16. 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.

17. 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)

18. 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.

19. 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

20. Treatment from Cyanobacteria
• creates a sound
barrier on top of
the water to
control the
growth
• Reducing the
amount of
nutrient loads
• Copper sulfate
and hydrogen
peroxide
• They can
reappear after
the treatment
• Manual
Removing
Physical
removal
Chemical
procedures
Ultrasonic
control
Biological
Inactivation

21. Cyanobacterial Toxins:
The cyanobacteria are proving to be a source of a large number of novel
organic compounds with biological activity
Anatoxins
Anabaena, Oscillatoria and Ap
hanizomenon
TOXIN
Nodularin Nodularia spumigena
TOXIN
Microcystins Microcystis

22. TOXINS
Aplysiatoxins Lyngbya
TOXINS
Cylindrospermopsin Cylindrospermopsis
raciborskii,Aphanizomenon ovalisporum
TOXINS
Saxitoxins PSP

23. 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

24. 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.

25. THANK YOU