Oscillatoria, derived from the Latin word “oscillare” meaning “to swing,” is a prevalent freshwater blue-green alga that thrives in diverse environments. Desikachary (1959) extensively reported 76 species of Oscillatoria.
Occurrence
Typically, it forms a dense, dark growth in polluted and stagnant waters and in pools, ponds, riverbanks, canals, streams, and sewers. It can be found on moist soil and roadside ditches during the rainy season.
Ancient ponds and other water reservoirs often exhibit a substantial coating of Oscillatoria. O. prolifica is a planktonic species, while O. terebriformis is a thermal alga. O. sancta is commonly found on wet or moist walls and soil.
Whereas O. limosa occurs in salt lakes near Kolkata (Biswas, 1926). O. princeps is versatile, thriving in freshwater, seawater, and moist soil (Desikachary, 1959).
Among the common species are O. annae, O. sancta, O. vizagapatensis, O. limosa, O. curviceps, O. princeps, O. proboscidea, O. decolorata, O. tenuis, O. raoi, and O. okeni.
Taxonomic Position
| Classification | Bacteria |
|---|---|
| Domain | Bacteria |
| Phylum | Cyanobacteria |
| Class | Cyanophyceae |
| Order | Oscillatoriales |
| Family | Oscillatoriaceae |
| Genus | Oscillatoria |
Oscillatoria General Features
Oscillatoria exhibits distinctive characteristics, which can be summarized as follows:
- The plant body of Oscillatoria takes the form of an unbranched filament known as a trichome. These trichomes can either be uncovered or encompassed by a thin, underdeveloped mucilaginous sheath.
- Each trichome consists of numerous closely arranged cells that are uniseriate. The cells are wider than long and can be distinguished into a cell wall and protoplasm.
- Within the cells, a range of pigments, such as chlorophyll-a, carotenes, xanthophylls, phycocyanin-c, and phycoerythrin-c, are present in the chromoplasm.
- The cyanophycean starch is the reserve food material, supporting the organism’s energy requirements.
- Growth predominantly occurs through the amitotic division of intercalary cells within the trichomes.
- Oscillatoria displays various movements, including gliding, oscillating, crawling, and bending, showcasing its agility and adaptability.
- Reproduction in Oscillatoria exclusively takes place through vegetative means, primarily by fragmentation and the formation of hormogonia.
Structure
Oscillatoria exhibits trichomes that can either stand-alone or fuse together to create a well-defined spongy layer. These layers come in shades of black, bluish-green, or dark blue-green, with thousands of filaments entwined within them.
The filaments are flat, straight, and can be twisted or curved. Each trichome represents a long, unbranched thread-like structure composed of numerous cells.
While most trichomes lack a surrounding mucilaginous sheath, a few species, like O. formosa, possess an exceptionally delicate sheath. Typically, the cells within the trichomes are broader than they are tall.
There are no constrictions at the septa, the points where the trichomes divide. Although the apex of the trichome does not exhibit clear differentiation from its base, the terminal cell often assumes a distinct shape depending on the species, as described below:
Different species of Oscillatoria exhibit distinct shapes for their capitate structures.
- Oscillatoria princess, O. grunowiana, and O. amoena feature capitate forms.
- O. rubescens takes on an oval shape.
- O. salina and O. acuminata have acuminate structures.
- O. proboscidea displays a capitate form with a thick membrane.
- O. splendida appears round.
- O. miniata showcases an obtuse or attenuated shape.
- Additionally, O. anguina exhibits a calyptrate structure.
In most Oscillatoria species, the apex is typically hemispherical, as observed in O. annae.
Cell Structure
When observed under a light microscope, the cell structure of Oscillatoria aligns with the general characteristics of Myxophycean cells. The cell wall encompasses a dense mass of granular protoplasm. Notably, Oscillatoria lacks a distinct nucleus enclosed by a nuclear membrane.
![]An enlarged cell](https://biologynotesweb.com/wp-content/uploads/2023/06/Oscillatoria-—An-enlarged-ce.webp)
Within the protoplasm, there is a differentiation between the outer colored region, known as chromoplasm, containing pigments, and the colorless inner region, called centroplasm, which represents the early stages of nucleus formation.
When examined under an electron microscope, Oscillatoria shows specific structural characteristics. Typically, there is no mucilaginous sheath surrounding the cell wall. The cell wall itself measures approximately 2000 Å in thickness.
Adjacent to the cell wall, we find the plasma membrane. Halfen (1973) identified two additional layers in the outer region of the cell wall. One layer is approximately 160 Å thick, while the other measures 90 Å in thickness. Numerous pores are present within the structural layer.
Notably, Oscillatoria lacks plastids, mitochondria, endoplasmic reticulum, and dictyosomes. The pigments are primarily located in well-developed thylakoids or lamellae. While predominantly concentrated in the chromoplasm region, they may also distribute throughout the cell.
Additional features include the presence of cyanophycean starch, cyanophycin granules, and pseudo vacuoles. Furthermore, the region of centroplasm contains numerous chromatin granules and crystalline bodies.
Movement
While motile cells are not present in Myxophyceae, the individual filaments of Oscillatoria exhibit a distinctive pendulum-like oscillating or swinging movement, readily observable in live samples. The filaments of Oscillatoria show the following types of movements:
- Oscillatory Movement: The filaments’ terminal part oscillates like a wall clock’s pendulum. This movement is appropriately termed “oscillatory movement.” The genus Oscillatoria derives its name from this characteristic oscillatory motion.
- Gliding Movement: This movement occurs along the filaments’ long axis and is often called “creeping movement.” The trichomes move forward and backwards during gliding, creating a smooth gliding effect.
- Bending Movement: The filaments display bending movement facilitated by the rapid bending of the extreme tip after each oscillation. This bending motion adds to the filament’s overall dynamic behaviour.
Reproduction
Oscillatoria only reproduces through vegetative means, specifically by utilizing two known methods: the formation of hormogones and fragmentation.
Hormogones
Hormogones are short segments of trichomes composed of multiple undifferentiated vegetative cells. In Oscillatoria, hormogones typically consist of cells situated between two separation discs.
These separation discs are pad-like structures filled with mucilage and possess a biconcave shape, resulting from the death of one or more cells within the filament. These mucilage-filled cells are also referred to as necridia.
The presence of mucilaginous separation discs enables the detachment of hormogones. Hormogones, or hormogonia, continue to move for a period and eventually function as new trichomes, perpetuating the reproductive cycle of Oscillatoria.
Fragmentation:
The filaments of Oscillatoria can undergo division, forming small pieces or fragments. This division can occur due to the biting of certain insects or young animals and through mechanical or other factors.
Significantly, each of these fragments can develop into a new individual, contributing to the reproductive capabilities of Oscillatoria.
Applications of Oscillatoria
Environmental Applications of Oscillatoria
Bioremediation and Wastewater Treatment
In the field of bioremediation, Oscillatoria possesses remarkable features. It can effectively remove contaminants from effluent and polluted environments due to its tolerance for high levels of pollutants, such as heavy metals and organic compounds.
Its photosynthetic activity and capacity to sequester nitrogen also contribute to ecosystem restoration and water quality improvement.
Carbon Sequestration
Carbon sequestration has appeared as a significant topic of study in the face of climate change. With its ability to trap and store ambient carbon dioxide, oscillatoria has the potential to play a substantial role in reducing greenhouse gas emissions.
Oscillatoria utilizes its photosynthetic capabilities to effectively capture carbon from the atmosphere and sequester it in the soil.
Agricultural and Food Industry Applications
Biofertilizer and Soil Enhancement
Oscillatoria has nitrogen-fixing qualities making it a vital help in agriculture. This cyanobacterium can create symbiotic relationships with plants, supplying them with a sustainable and renewable nitrogen source.
Farmers can reduce reliance on synthetic fertilizers by adopting Oscillatoria-based biofertilizers, boosting soil health and decreasing environmental impacts.
Nutraceutical and Functional Food Production
Oscillatoria has the potential to produce nutraceuticals and functional foods. Oscillatoria, high in protein, vital amino acids, vitamins, and antioxidants, can be a source of valuable nutrients.
Incorporating Oscillatoria into food products improves their nutritional profile and potentially provides health advantages.
Medical and Pharmaceutical Applications
Antibacterial and Antifungal Properties
Oscillatoria, according to research findings, displays notable antibacterial and antifungal properties, positioning it as a promising contender for developing natural antimicrobial agents.
The effectiveness of its bioactive compounds against diverse pathogens underscores its potential significance in medicine and pharmaceuticals.
Drug Delivery Systems
Oscillatoria’s filamentous structure holds potential as a scaffold for drug delivery systems. Its biocompatibility, biodegradability, and ease of modification make it an appealing choice for encapsulating and transporting therapeutic agents.
This innovative technique holds promise in targeted drug delivery, enhancing treatment efficacy while minimizing adverse effects.
Key Points:💡
- Oscillatoria is a freshwater blue-green alga that thrives in diverse environments, including polluted and stagnant waters, pools, ponds, canals, and sewers.
- It is also commonly observed on damp soil and roadside ditches during the rainy season.
- Ancient ponds and water reservoirs often have a substantial coating of Oscillatoria.
- There are several species of Oscillatoria, each with its habitat preference.
- Oscillatoria exhibits an unbranched filament structure called a trichome, composed of closely arranged cells with various pigments.
- The reserve food material of Oscillatoria is cyanophycean starch.
- Oscillatoria displays various movements, including gliding, oscillating, crawling, and bending.
- Reproduction in Oscillatoria primarily occurs through vegetative means, such as fragmentation and the formation of hormogones.
Frequently Asked Questions
Oscillatoria are primarily found in freshwater environments, such as pools and ponds. However, certain marine species, including O. sancta and O. salina, can also be encountered in marine habitats.
Cyanobacteria, or blue-green algae, are a diverse group of prokaryotic organisms that are primarily photosynthetic.
Cyanobacteria, a photosynthetic bacteria, thrive abundantly in freshwater and marine habitats. They can exist as solitary cells or form colonies, showcasing their versatility. Notable examples of cyanobacteria include Oscillatoria, Nostoc, Spirulina, and Anabaena.
Hormogonium refers to a compact section of the filament situated between two deceased cells within the trichome. These structures undergo rapid multiplication and eventually detach themselves from the surrounding mucilaginous sheath, giving rise to new filaments.
Cyanobacteria, commonly known as “blue-green algae,” including species like Oscillatoria, is a widespread bacterial group prevalent in freshwater ecosystems across the globe. These bacteria have been associated with health issues and, in certain instances, even fatalities among humans and animals.
The unique blue-green color exhibited by these organisms, from which they derive their common name, results from combining phycobilin and chlorophyll pigments. However, it is essential to note that due to other pigments, many species can display shades of green, brown, yellow, black, or red, adding to their diverse visual range.
Cyanobacteria earned their name from the blue-green pigment they possess, yet their blooms can display various colors, including green, blue-green, green-brown, or red. In contrast, algae and aquatic plants typically appear green, although they may take on hues of yellow or brown as they decline.
References and Sources:
- Algae book by Op Sharma
- The Algae Book By v. J. CHAPMAN
- THE BLUE-GREEN ALGAE Book By G. E. FOGG, W. D. P. STEWART
- https://en.wikipedia.org/wiki/Oscillatoria
- https://www.sciencedirect.com/topics/medicine-and-dentistry/oscillatoria