Basic about Nostoc

1. Algae:Nostoc
Prepared by:
Md. Shakiur Rahman
ID: 170711
Biotechnology and Genetic Engineering Discipline
Khulna University,Bangladesh.

2. Morphology of Nostoc :
• Thalli are present in the form of colony.
• Ball like colony is enveloped by a gelatinous sheath.
• Balls are greenish to bluish-green in colour.
• Each colony contains thousands of straight or twisted filaments or
trichomes.
• Each trichome is surrounded by its individual sheath and called the
filament.
• A trichome is contorted and consists of many cells arranged in a
beaded manner

3. • Each cell is somewhat cylindrical or
spherical in shape.
• In filaments there are present some large,
spherical or cylindrical, colourless empty
cells called hetero cysts.
• Heterocysts are generally intercalary but in
the young condition, they may be terminal.
• Two polar nodules are present in each
heterocyst.
• Some cells of the filament become
enlarged and filled with the food material.
These thick-walled cells are called akinetes.
• Akinetes are generally present in chain.
Fig: A single filament of Nostoc

4. Fig: A. single vegetative cell
B. HeterocystFig: A. Part of colony under low power
B. Part of colony under high power

5. A Single Cell of Nostoc
• Each cell is surrounded by a cellulose cell wall.
• Protoplast shows the typical Myxophycean structure, i.e., inner
colourless centroplasm and outer pigmented chromoplasm.
• In the chromoplasm are present pigments, proteinaceous
cyanophycin granules and cyanophycin starch granules
• while in the centroplasm is present the incipient nucleus.

6. Occurrence of Nostoc
Nostoc can be found in
• soil
• on moist rocks
• at the bottom of lakes and springs (both fresh- and saltwater)
• rarely in marine habitats.

7. Characteristics of Nostoc
• Nostoc, genus of blue-green algae with cells arranged in beadlike
chains that are grouped together in a gelatinous mass.
• Size ranging from microscopic to walnut.
• Masses of Nostoc may be found on soil and floating in quiet water.
• Reproduction is by fragmentation.
• A special thick-walled cell (akinete) has the ability to withstand
desiccation for long periods of time.
• After 70 years of dry storage, the akinete of one species germinates
into a filament when moistened.

8. • Like most blue-green algae, Nostoc contains two pigments, blue
phycocyanin and red phycoerythrin, as well as chlorophyll.
• It has the ability to fix nitrogen in specialized cells called heterocysts.
• A terrestrial species has been used as a supplementary food source in
Asia.

9. Biotechnological Importance of Nostoc
• Nostoc has been used as dietary supplements for centuries.
• Several edible species (i.e., N. commune, N. sphaeroides, and N.
flagelliforme) have been collected from various natural habitats for
human use.
• Recently, the nutritional value of the edible Nostoc species has been
characterized and a number of pharmacological studies suggest that
Nostoc contains a variety of bioactive compounds with the antitumor,
antioxidant, or anti‐inflammatory functions.
• To meet the increasing market demands, mass cultivation of Nostoc
has been attempted during the past decades.

10. • Research on the morphological development, pharmaceutical values,
growth, and physiology of Nostoc, with an emphasis on the edible species
has been successfully done.
• The edible species has been successfully cultivated at pilot scale, several
technical challenges including the low growth rate, loss of colonies, and
high cost of photobioreactors remain to be overcome for
commercialization in the future.