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
6. HABITAT
โซ Microscopic forms occur ubiquitously in nature
โซ mostly aquatic,occurring in fresh , brakish and
marine water.
โซ Some form symbiotic associations with higher
plants,bryophytes ,lichens and protists
โซ They occur as planktonic forms or as benthic
forms
โซ some form phototrophic biofilms
โซ They occur on moist trunks , moist soils and in
extreme conditions like hot springs โ frozen lakes
and salt water
7. โซThough not related to
algae(eukaryotic) they were earlier
classified under algae
โซLater found that it has more
characteristics similar to bacteria
. Some of them fix atmospheric
nitrogen eg. nostoc , Anabena
8. โซMorphology of cyanobacteria
โซUnicellular , colonial or filamentous .
โซEach filament covered in sheath of
mucilage in which cellular strands
โซcalled trichomes
โซFlagella absent but some show gliding
movement
10. Cell structure
โซ Cyanobacterial cells range in size from 0.5-1 ฮผm to 40 ฮผm in
diameter
โซ Cells larger than bacteria more elaborate than
โซ Prokaryotic in nature
โซ Presence of mucilagenous sheath, a characteristic feature
outside cell wall
โซ Cell Wall; four layered .peptidoglycan is second layer
โซ Outer layer of protoplast has photosynthetic thylakoids
โซ It is called chromoplasm
โซ Thylakoids freely found
โซ Their membranes contain chlorophyll a , carotenes and
xanthophylls
โซ Attached to outer layer- phycobillosomes
11. โซ Plasma membrane present below cell wall
โซ Made of protein-lipid layer
โซ Cytoplasm divided into outer pigmented
region โchromoplasm
โซ inner colourless central region called
centroplasm
โซ Chromoplasm โhas flattened vesicles called
thylakoids containing pigments such as
โซ Chlorophyll,carotenoids and
phycobillins(phycocyanin,phycoerythrin and
alloerythrin)
12. โซCentoplasm has a nucleoid or
incipient nucleus
โซSegmented circular DNA ,small circular
DNA present,70S ribosome
โซFood storage-cynophycean starch
โซ(alpha granules)
โซProtein granules and lipid granules
โซPresence gas vacuoles also called
pseudo-vacuoles
โซHelp in buoyancy
13. โซPresence of specialised cells -
HETEROCYST
โซPale yellow,Thick-walled,nodules,larger
than other vegetative cells with
homogenenous content intercalary in
position
โซ specialized cells help in nitrogen fixation
contain nitrogenase enzyme
15. ,
โซ GAIDUKOV PHENOMENON OR
COMPLEMENTARY CHROMATIN
ADAPTATION
โซ The efficiency to change pigment
composition to absorb maximum light for
photosynthesis,with variation of incident
light-Gaidukov phenomenon
โซ 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. โซ 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
19. โซSpore formation
โซAkinetes 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. โซExospores
โซ formed outside,cut off from
โซTip during favourable conditions
โซHeterocyst
โซSometimes during unfavourable conditon
โซHelp in reproduction
โซGerminate during favourable condition
โซTo new filaments
21. โซ Economic importance
โซ 1)Important role in evolution of early earth -made
earth oxygenic by utilising water for photosynthesis
,fix co2
โซ And liberate oxygen
โซ 2)fix atmospheric nitrogen โthrough heterocyst hence
used as biofertilizer.
โซ 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
23. โซ 3)Role in bioremidiation
โซ impoving soil quality in saline soils by sodium
removal(bioremediation) .eg Phromedium reduces the
quality of brine).
โซ 4)Used in waste-water treatment too
โซ 5)Act as first colonizers in soil reclaimation.
โซ 6)Improve water holding capacity
โซ 7)Increase soil biomass after their death
โซ 8)Used as bio-inoculant- as they produce
โซ bio-active substances such as growth harmones,enzymes
(increase yield in paddy), and maintain soil health
โซ 9)increase phosphate content in soil
โซ 10)prevent soil erosion by binding soil
24. โซ9) form base of aquatic food chain act as
primary producers.
โซ 10)As a part of phytoplanktons contribute in
adding oxygen to atmosphere
โซ 11)Role as nutritionalfood supplement
โซ Certain species of cyanobacteria serve as food
โซ 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),
โซSpirulina are considered super food with
excellent nutritional content
โซHigh protein and vitamin content.source
of B12
26. โซ 13) species of Lyangbia are used in preparation
of antibiotics
โซ 14)Many species of cyanobacteria grown in large
number form algal blooms in aquatic bodies
.they produce potent toxins โ
hepatotoxin,nerutoxin.
โซ They change quality of water by producing
offensive odour,colour and make water unpotable
โซ Cattles and other lifestock when they consume
such water are killed
โซ Finally the water body will sustain no life
โซ Due to anoxia.
27. โซThe important toxins producing
cyanobacteria are Microcytis aeruginosa,
โซAnabena flosaquae
โซ.
28. โซ15)Cyanobacteria can grow on walls and
roof of building during rainy season
causing discolouration,corrosion and
leakage
29. Synecocystis
โซ 13)As a source of bio-fuel โas
environmental friendly,cheap source.
โซ Genetically engineered cyanobacteria used a
source bio-disel,bio-hydrogen,bio-methane
โซ 14)As a tool or model organism for
scientific studies
โซ Cyanobacteria such as Synechocystis widely
used as system to study principles of
photosynthesis
โซ 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