cyanobacteria general characteristics

1. CYANOBACTERIA
Mrinalini Devi .U.G

2. Classification
Domain-Bacteria
Kingdom –Monera
Division-Eubacteria
Class-Cyanobacteria

4. Cyanobacteria
cyanobacteria previously know
as blue-green algae
group of photoautotrophic ,gram negative
bacteria
get their name cyanobactria (cyan-blue
due to the blue pigment phycocynin
present along with chlorophyll-a
Some red or pink pigment called
phycoerythrin
Evolved 3.5 billion years ago
Includes 150 genera and 2,798 sps

5. Alglal bloom in red
sea(Tricodesmium erythraeum)

6. HABITAT
 Microscopic forms occur ubiquitously in nature
 mostly aquatic,occurring in fresh , brakish and
marine water.
 Some form symbiotic associations with higher
plants,bryophytes ,lichens and protists
 They occur as planktonic forms or as benthic
forms
 some form phototrophic biofilms
 They occur on moist trunks , moist soils and in
extreme conditions like hot springs ‘ frozen lakes
and salt water

7.  Though not related to
algae(eukaryotic) they were earlier
classified under algae
 Later found that it has more
characteristics similar to bacteria
. Some of them fix atmospheric
nitrogen eg. nostoc , Anabena

8.  Morphology of cyanobacteria
 Unicellular , colonial or filamentous .
 Each filament covered in sheath of
mucilage in which cellular strands
 called trichomes
 Flagella absent but some show gliding
movement

9.  Ultra structure of Cell

10. Cell structure
 Cyanobacterial cells range in size from 0.5-1 μm to 40 μm in
diameter
 Cells larger than bacteria more elaborate than
 Prokaryotic in nature
 Presence of mucilagenous sheath, a characteristic feature
outside cell wall
 Cell Wall; four layered .peptidoglycan is second layer
 Outer layer of protoplast has photosynthetic thylakoids
 It is called chromoplasm
 Thylakoids freely found
 Their membranes contain chlorophyll a , carotenes and
xanthophylls
 Attached to outer layer- phycobillosomes

11.  Plasma membrane present below cell wall
 Made of protein-lipid layer
 Cytoplasm divided into outer pigmented
region –chromoplasm
 inner colourless central region called
centroplasm
 Chromoplasm –has flattened vesicles called
thylakoids containing pigments such as
 Chlorophyll,carotenoids and
phycobillins(phycocyanin,phycoerythrin and
alloerythrin)

12.  Centoplasm has a nucleoid or
incipient nucleus
 Segmented circular DNA ,small circular
DNA present,70S ribosome
 Food storage-cynophycean starch
 (alpha granules)
 Protein granules and lipid granules
 Presence gas vacuoles also called
pseudo-vacuoles
 Help in buoyancy

13.  Presence of specialised cells -
HETEROCYST
 Pale yellow,Thick-walled,nodules,larger
than other vegetative cells with
homogenenous content intercalary in
position
 specialized cells help in nitrogen fixation
contain nitrogenase enzyme

14. Akinetes
thick-walled ,enveloped,
non-motile , dormant cell
Contain food reserve produced to
tide over unfavourable condition
Over unfavourable condition

15. ,
 GAIDUKOV PHENOMENON OR
COMPLEMENTARY CHROMATIN
ADAPTATION
 The efficiency to change pigment
composition to absorb maximum light for
photosynthesis,with variation of incident
light-Gaidukov phenomenon
 cyanobacteria have the capacity to change
colour in relation to wavelength of incident light

16. Reproduction
Vegetative and asexual methods
1) vegetative
Fragmentation
At regular intervals filaments get cut for
short pieces of 5-15 cells called
hormogonia
Show gliding movement
Later develop into full fledged filaments
filament

17.  Asexual reproduction
1. Binary or multiple fission
2. hormospores
3. Spore formation a)Akinetes b)endospores
c)exospores
Binary repoduction
simple type of cell division.First genetic
genetic material separate moves to
to opposite pole.A ring-like ougowth appears
in the middle and divide into two

18.  Hormospores
under unfavourable conditions
some cells develop thick wall
such cells called harmospores
germinate in favourable conditions

19.  Spore formation
 Akinetes or arthospores
thick-walled,enveloped reproductive structures
1. Store reserve food material
2. Yellow-brown in colour
3. Germinate in favourable condition
Endospores
Some cyanobacteria produce them

20.  Exospores
 formed outside,cut off from
 Tip during favourable conditions
 Heterocyst
 Sometimes during unfavourable conditon
 Help in reproduction
 Germinate during favourable condition
 To new filaments

21.  Economic importance
 1)Important role in evolution of early earth -made
earth oxygenic by utilising water for photosynthesis
,fix co2
 And liberate oxygen
 2)fix atmospheric nitrogen –through heterocyst hence
used as biofertilizer.
 Azolla is a fast growing free floating freshwater fern
which fixes atmospheric nitrogen by forming a symbiotic
association with a prokaryotic cyanobacterium -Anabaena
azollae. It is a cost-effective, eco-friendly biofertilizer
in lowland rice fields. As green manure in water logged soil,
it enhances the rapid mineralization of nitrogen, improves
the physical and chemical properties of the soil

22. Paddy field with azolla

23.  3)Role in bioremidiation
 impoving soil quality in saline soils by sodium
removal(bioremediation) .eg Phromedium reduces the
quality of brine).
 4)Used in waste-water treatment too
 5)Act as first colonizers in soil reclaimation.
 6)Improve water holding capacity
 7)Increase soil biomass after their death
 8)Used as bio-inoculant- as they produce
 bio-active substances such as growth harmones,enzymes
(increase yield in paddy), and maintain soil health
 9)increase phosphate content in soil
 10)prevent soil erosion by binding soil

24.  9) form base of aquatic food chain act as
primary producers.
 10)As a part of phytoplanktons contribute in
adding oxygen to atmosphere
 11)Role as nutritionalfood supplement
 Certain species of cyanobacteria serve as food
 And nutrtional supplement such as complex
sugar,protein,amino acids,active
enzymes,phycocyanin,cholorphyll,beta
carotene,essential fatty acid minerals,carohydrates
and vitamins

25. 12)Act as SCP( single celled protein)
eg.Spirulina and certain species of nostoc
(N.commune),
 Spirulina are considered super food with
excellent nutritional content
 High protein and vitamin content.source
of B12

26.  13) species of Lyangbia are used in preparation
of antibiotics
 14)Many species of cyanobacteria grown in large
number form algal blooms in aquatic bodies
.they produce potent toxins –
hepatotoxin,nerutoxin.
 They change quality of water by producing
offensive odour,colour and make water unpotable
 Cattles and other lifestock when they consume
such water are killed
 Finally the water body will sustain no life
 Due to anoxia.

27.  The important toxins producing
cyanobacteria are Microcytis aeruginosa,
 Anabena flosaquae
 .

28.  15)Cyanobacteria can grow on walls and
roof of building during rainy season
causing discolouration,corrosion and
leakage

29. Synecocystis
 13)As a source of bio-fuel –as
environmental friendly,cheap source.
 Genetically engineered cyanobacteria used a
source bio-disel,bio-hydrogen,bio-methane
 14)As a tool or model organism for
scientific studies
 Cyanobacteria such as Synechocystis widely
used as system to study principles of
photosynthesis
 As they can be grown easily in liquid culture
and can be manipulated genetically.

30. Paralellism between bacteriacyanobacteria
BACTERIA CYANOBACTERIA
1. Prokaryotic cell
(no nuclear membrane,70S
ribosome,lack histone
protein,no cell
organelles,presence of
peptidoglycan
Prokaryotic cell
2) sensitive to antibiotics Sensitive to antibiotics
3)Lack true sexual
reproduction
3)Lack true sexual
reproduction
4)Some forms fix atmospheric
nitrogen .eg.
Rhizobium,Azatobacter
4)Also fix atmospheric
nitrogen.
Eg.filamentous forms like
nostoc,Anabena fix
nitrogen
5)Many similar metaboilc
processes eg.sulphur and
5)Many similar metaboilc
processes eg.sulphur and