Nostoc - Structure, Reproduction and Economic Importance

Nostoc: Nostoc is a genus of blue-green algae or cyanobacteria, which are prokaryotic organisms that perform photosynthesis.  They are mostly found in freshwater environments, either as individual colonies or attached to rocks or the lakebed. They can also be found on tree trunks and as lichens in certain bryophytes like Anthoceros. Nostoc algae are capable of nitrogen fixation and act as photosynthetic agents. They also serve as endosymbionts for fungi. Students must carefully study these details when preparing for their exams. The article below contains Nostoc NEET Biology Notes for a better understanding.

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Nostoc Meaning

Mammary Glands

Nostoc Classification

Okazaki Fragments

1. Nostoc commune: This species is consumed as a salad.
2. Nostoc azollae: Forms a symbiotic association with water fern.
3. Nostoc punctiforme: Forms a symbiotic relationship with Anthceros and other higher plants.
4. Nostoc flagelliforme: Known as Fat choy, this species is used as a vegetable in China.
5. Nostoc pruniforme: Forms very large colonies, with diameters reaching approximately 25 cm.

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Nostoc Structure

1. Filaments: Nostoc colonies are made up of long, thread-like filaments called trichomes, which are composed of individual cells, each of which contains a single, compacted chromosome.
2. Heterocysts: Within the filament, specialized cells called heterocysts are regularly present. Heterocysts are characterized by their thick, colorless cell walls and lack of photosynthetic pigments. These cells play a vital role in nitrogen fixation, converting atmospheric nitrogen into a form the organism can use.
3. Branches: Some species of Nostoc may also exhibit branching filaments, which contribute to the overall structure and organization of the colony.
4. Mucilaginous Sheath: Surrounding the filaments is a gelatinous sheath, or mucilage, which helps to protect the colony from desiccation and provides buoyancy in aquatic environments.
5. Hormogonia: Under favorable conditions, Nostoc can reproduce asexually by forming specialized cells called hormogonia. These cells can move away from the parent colony and establish new colonies in suitable habitats.

Sexual Reproduction in Flowering Plants

Nostoc Reproduction

Fragmentation

• Trichomes (filaments) divide into smaller segments as a result of physical disruption, aging, or cell death.
• Each fragment, as long as it contains at least one vegetative cell, has the potential to form a new colony.

Plasma Membrane Structure

Spore Formation

1. Akinetes: These are dormant, thick-walled spores that form through the enlargement and modification of vegetative cells.  Akinetes are produced under adverse conditions such as nutrient scarcity or drought. The strong wall protects the genetic material inside, allowing Nostoc to withstand harsh conditions for long periods of time. Upon the return of favourable conditions, akinetes germinate and give rise to new filaments.
2. Hormogonia: These are brief, mobile filaments that result from the detachment of a segment of a trichome. Hormogonia can glide through water or moist soil thanks to its gelatinous sheath. They ultimately mature into new Nostoc colonies.

Hypotonic Solution

Nostoc Economic Importance

1. Soil Enhancement: Nostoc plays a crucial role in nitrogen fixation, enhancing the nutrient value of the soil. Paddy fields often use it to improve soil fertility and crop yields.
2. Food Source: Rich in proteins and vitamin C, Nostoc is a delicacy in various Asian countries. Species like N. flagelliforme and N. commune are popular choices in culinary dishes.
3. Industrial Applications: N. muscorum has shown potential in accumulating polyhydroxybutyrate, a plastic precursor. This suggests its possible applications in bioplastics and other industrial processes.
4. Biofuel Production: Nostoc can convert CO2 to biofuels, offering a sustainable alternative to fossil fuels. Its ability to produce hydrogen also makes it a candidate for biofuel production.
5. Bioremediation: Nostoc can be used for bioremediation of wastewater and degradation of environmental pollutants. Its ability to degrade toxins makes it valuable in cleaning up polluted environments.
6. Medicinal Potential: Various species of Nostoc, such as N. muscorum, N. commune, and N. insulare, have shown antibacterial or antiviral activity. This suggests their potential in drug development and pharmaceutical applications.