2. INTRODUCTION
Nostoc is a filamentous cyanobacteria or Blue
green algae forms of both terrestrial and aquatic
habitats.
It doesn’t occur in single filaments and grows in large
colonies.
They are found in ponds ditches and damp soils.
And few species lie in intercellular cavities of plants
like duck web.
Nostac colony thus forms a mucilagenous lump or
thallus which occur floating or attached.
Nostoc is capable of fixing Nitrogen.
4. ULTRA STRUCTURE
It is blue green algae of filamentous form.
Nostoc consists of many slender long & short inter
woven filaments which look like a chain of beads .
Each filaments is unbranched & consists of row of
rounded or oval cells.
There is a often a gelatinous sheath covering each
filament is known as mucligenous sheath.
Each cell is differentiated into two regions called
chromoplasm(the outer region is blue green
poigmented) & the inner colourless region called
centroplasm.
5.
6. The filament increases in length by cell division in one
plane only.
Some enlarged vegetative cells with thickened walls &
transparent contents are seen to occur at frequent
intervals & also at the ends are called heterocysts.
A pore is present to each pole of the heterocyst
maintaining cytoplasmic connection with adjoining cells .
There is one pore at the terminal heterocyst
At the later stage the pore is closed by a button like
thickening of the cell wall called polar molecules.
7. REPRODUCTION
Nostoc reproduces vegetatively & asexually.
Sexual reproduction is absent.
All the filaments of the colony reproduce
simultaneously.
The sexual reproduction is totally absent nostoc
reproduce only vegetatively by following methods
Framentation
Horomogonia
Akinetes
Heterocysts
Fusion
8. FRAGMENTATION
By mechanical , physiological or by the colony breaks
into 2 or more fragments.
Each of fragments is capable to develop into new colony
of nostoc.
9. HORMOGONIA
It is one of the very common methods of
reproduction in nostoc.
The filaments may breaks into a number of pieces
because of the decay of ordinary vegetative cells or
owing to the appearance of heterocyst.
The detailed structure of vegetative cell of nostoc is
similar to that discused in the general account of
myxophycean cell.
10. ASEXUALLY REPRODUCTION
AKINETES
An akinete is thick walled dormant cell derived
enlargement of vegetative cell.
These are also called as resting spores or
arthrospores & formed by many species of nostoc.
Large a mount of reserve food materials along with
the cyanophcin granules is being stored by the
akinetes.
In favourable conditions they directly or indirectly
giving rise to new filaments.
The contents of akinetes divide into bits prior to
germination .
11.
12. HETEROCYST
Rarely the heterocysts become functional and
germinates to form a new filament in a few species
like N.Commcene.
During germination the heterocyst divide first into 2
celled and then into 4 celled which ruptures the
outer wall comes out and develops into a new
filament.
Heterocysts are specalized Nitrogen fixing cells.
They are formed during nitrogen starvation by
filamentous Cyanobacteria.
They are of same shape as of vegetative cells and
are mutually independent.
13. SIGNIFICANCE
Nostoc colony are rich in nitrogenous substances.
Hence they are used as food in China and Brazil.
Nostoc colonies increases nitogen contents of the
soil and are often used as fertilizer to increase the
crop productivity.(such as paddy).
Nostoc is capable of fixing nitogen and grows
rapidly.
Nostoc is used,because of these properties,in
reclamation of usuar(alkaline and saline) and
barren soil.
15. INTRODUCTION
Spirulina is a filamentous micro-Cyanobacteria and are
photoautotrophs.
It is composed of cylindrical cells arranged in
unbranched,helicoidal trichomes.
They are found in a variety environment such as Soil,
Sand, Marshes,Brackish water ,Sea,Water and Fresh
water.
The planktonic species of spirulina occurs frequently in
Shallow,alkaline lake of high salinity in the entire
African continent and in South America.
Spirulina a micro-Cyanobacterium posses high value
biochemical constituents that find applications in areas
like Health Foods and Therapeutics.
Spirulina species has been produced commercially all
over the world due to its high contents of proteins
(upto 70%).
16. ULTRASTRUCTURE
Spirulina is a Filamentous Cyanobacteria and cell
wall is formed by 4 numbered layers.
The layers are L1, L11, L111 and L1V and these
layers are weak except layer L11.
Because L11 is made up of peptidoglycon.
Hence the substance that gives the wall its rigidity.
The L11 layer contains b-1, 2-glucan, a
polysaccaride and not very digestable by
human beings.
17. The protein and lipopolysaccharide nature of the L11
layer are favourite reasons for the easy human digestion
of spirulina.
In spirulina- Chlorophylla, carotenes and phycobilisarus,
which contains phylocyanin (blue pigment) are located in
the thylakoid systems/photosynthetic lamellar.
The inter thylakoid space is limited by the presence of
electronically transparent protein Gas vesicles, with the
cylindrical form the gives spirulina its floating capacity.
18. REPRODUCTION
In spirulina Reproduction takes place asexually by
Binary Fission.
Sexual reproduction is absent.
BINARY FISSION
It means a single cell is splitting into 2 cells.
It is is a type of asexual reproduction where inside the
cell a division develops on the middle of the organisms.
The division eventually completely divides the bacterium
in half and known as Cytokinesis.
Each cell is now Gentically identical offsprings.
In binary fission ,it results into two identical
daughter cells.
19. SIGNIFICANCE
Spirulina is a natural (algae)/Cyanobacteria.
Spirulina is a ideal food and dietary supplement for
21st Century by Food and Agriculture Organization
(FAD).
Spirulina powder is incredibily high in proteins i.e
more than 60% and good source of antioxidants,
B-Vitamin and other Nutrients.
Spirulina is added to numerous types of pet foods.
20. It is largely made up of proteins and essential
Amino Acids and high Natural iron contents.
Spirulina is also used as Antiviral because it has all
biochemicals in its constitution. That can build a
Healthy Immune System which scavengers free
radicals as well as cpds.
Extracted from Arthrospira have inhibitory activity
against a wide range of viruses such as HIV-1, HSV-
1, HSV-2 , HCMV, Influenza Type-A ,Measles.
Spirulina is also used as Anticancer Agent and also
used as Capsules and Tablets as Nutrients and for
Weight loss also.
Hence spirulina has many Beneficial Facts.