Oscillatoria Characteristics

Oscillatoria is a type of filamentous cyanobacteria, commonly known as blue-green algae.

Oscillatoria characteristics are as follows:

1. Structure: Oscillatoria is a fresh water, blue green alga, represented by 76 species. It is

composed of long, unbranched filaments made up of a single row of cells. These filaments

can occur singly or tangled together in mats, surrounded by a thin, jelly-like sheath.

2. Movement: Its name refers to the oscillating motion of its filaments as they slide against

each other to position the colony to face a light source. Oscillatoria exhibits a slow,

swaying motion, from which it gets its name. This movement is believed to be caused by

the release of mucilage, pushing the filament away as it is secreted. This motion helps the

algae position itself towards light sources for photosynthesis.

3. Photosynthesis: Oscillatoria uses photosynthesis to survive and reproduce.

4. Habitat: Species are commonly found in fresh and polluted water of ponds, pools, drains,

streams, and also in damp soils and rocks. It can also survive in brackish water and even

some hot springs. These algae thrive in warm, still water that is nutrient-rich.

 O. princeps grows in sea water and sub-aerial habitats.

 O. brevis can separation bear a temperature of -16°C

 O. terebriformis occurs in hot water springs (thermal algae).

 Some of saprophytic species are found in the digestive and respiratory tracts

of the animals.

5. Reproduction: Oscillatoria reproduces asexually through fragmentation. Under

favorable conditions, a filament can break into smaller pieces known as hormogonia, each

capable of growing into a new filament.

6. Color: Oscillatoria usually appears blue-green due to pigments like phycocyanin and

chlorophyll. However, some species may exhibit colors ranging from green to brown,

yellow, black, or red. These form bluish scums on water surface or at pond-bottom.

While many Oscillatoria species are harmless, some can produce toxins harmful to animals

and humans. It’s important to avoid contact with water containing large blooms of Oscillatoria

for safety.

Oscillatoria Classification

Domain Bacteria

Phylum Cyanobacteria

Class Cyanophyceae

Order Oscillatoriales

Family Oscillatoriaceae

Genus Oscillatoria
 Oscillatoria Structure

Oscillatoria is a type of filamentous cyanobacteria that forms long chains or filaments of

cylindrical cells. The following is the detailed structure of Oscillatoria.

1. Thallus: The body of Oscillatoria, known as a thallus, consists of a single unbranched

thread.

 It is composed of a row of cells that develop into unbranched filaments covered

with a gelatinous coating.

 Oscillatoria is rarely found alone and can either be as interconnected or in free-

floating colonies.

 Most species often create either dense tangle masses or spongy sheets. The threads

can be placed in parallel rows or woven together.

2. Trichomes: Each filament of Oscillatoria consists of a row of cells called a trichome.

A mucilaginous sheath surrounds each trichome and consists of stacked cells.

 Each trichome is an un-branched, long, flat thread like structure made up of

numerous cells.

 The cells are broader than in their length and show prokaryotic organization.

 The trichome shows polarity.

 It possesses characteristic apical cell. It may be cap like (capitate) or covered by a

thick membrane called calyptra. The apical cell may also be conical, dome shaped,
 acuminate, oval, flattened convex or coiled and accordingly to the shape of the cap

cell, the species are identified (Fig. 3 A-H).

 The tip of the trichome oscillates like a pendulum.

 The filament also comprises biconcave dead cells called separation discs or

necridia. These dead cells are filled with mucilage.

 The small pieces of filaments present between adjacent necridia are called

hormogonia.

3. Cell Structure: Also, the cell structure somewhat resembles bacteria.

Thus, Oscillatoria is also called cyanobacterium. All cells in the trichome are similar

in structure. Each cell is made up of an inner protoplasm, a middle plasma membrane,

and an outside cell wall. Each cell of Oscillatoria, a filamentous cyanobacterium,

exhibits a characteristic organization and composition:

1) Cell Wall: The outermost layer of the cell is the cell wall, which is bilayered and

contains numerous pores. It provides structural support and protection to the cell. The

cell wall is a bi-layered structure and has many pores. A mucilage sheath also encircles

the cell wall. Hemicellulose and pectin make up the rigid cell wall.

2) Mucilage Sheath: Surrounding the cell wall is a mucilaginous sheath. This slimy

sheath helps anchor the filament and trap water and nutrients.

3) Protoplasm: Inside the cell wall, the protoplasm is the living content of the cell. The

protoplasm is divided into

 a) Centroplasm: The central, colorless region of the protoplasm. Ultrastructure of

cell shows that the chromoplasm contains photosynthetic lamellae or single

thylakoid which often run parallel to one another. The thylakoids contain

photosynthetic pigments like chlorophyll a, carotenes, xanthophyll’s and

phycobilins (C-phycocyanin, allophycocyanin, c-phycoerythrin). The

chromoplasm also has small gas vacuoles and many photosynthetic pigments.

b) Chromoplasm: The peripheral, pigmented region of the protoplasm that contains

various photosynthetic pigments and thylakoids (membranous sacs where

photosynthesis occurs).

4) Gas Vacuoles: Planktonic species of Oscillatoria possess gas vacuoles or

pseudovaculoles which are devoid of any membrane. It is made of a number of

‘hexagonal’ structures called ‘gas vesicles’ (Fig. 2B) within the chromoplasm that aid

in buoyancy and regulating the cell’s position in water.

5) Plasma Membrane: The plasma membrane surrounds the protoplasm, serving as a

selective barrier that regulates the passage of molecules into and out of the cell.

6) Nucleoid: Oscillatoria cells are prokaryotic, meaning they lack a true nucleus. Instead,

their genetic material, composed of irregularly arranged DNA fibrils, called nucleoid

and is dispersed in the nucleoid region within the protoplasm.

7) Ribosomes and Organelles: Although Oscillatoria cells lack membrane-bound

organelles such as mitochondria or chloroplasts, they contain small ribosomes

dispersed throughout the protoplasm. These ribosomes are responsible for protein

synthesis within the cell.

8) Photosynthesis: The chromoplasm of Oscillatoria cells contains photosynthetic

pigments like chlorophyll and phycobilins, which capture light energy for

photosynthesis. Thylakoids, where these pigments are embedded, play a crucial role

in this process.

9) The reserve food materials are present in the protoplasm, in the form of

cyanophycean starch, lipid, globules and cyanophycin. The protoplasm also contains

α and β granules. α granules contain proteins and polysaccharides while β granules

have lipid.
Figure: Filament of Oscillatoria showing details structure
 Reproduction in Oscillatoria:

Oscillatoria reproduces reproduces asexually only through two primary vegetative methods.

These are:

1. By fragmentation: It occurs due to accidental breakage of the filament into smaller pieces.

Filament divides into small pieces or fragments. These fragments, if they contain enough live

cells, can develop into new filaments. Each of these fragments is capable of developing into

new individual. Fragmentation can be triggered by various factors such as physical

disturbances, animal grazing, or even cell death within the filament.

2. By hormorgonia: Hormogonia or hormogones are short segments of trichome which

consists few cells. Hormogones are formed due to formation of separation discs. These discs

are mucilaginous, pad like and biconcave in shape. These are formed by death of one or more

cells of the filament. This mucilage filled dead cells are also called necridia. Hormogonia

formation is a more specialized form of asexual reproduction in Oscillatoria, involving

several steps:

 Specific cells within the Oscillatoria filament die and fill with sticky mucilage. These

cells are known as necridia or separation discs.

 The necridia separate living cell groups within the filament called hormogonia.

 The hormogonia are released from the parent filament.

 The hormogonia can grow and mature into new Oscillatoria filaments.
Oscillatoria does not undergo sexual reproduction, a more complex process involving the

fusion of gametes from different individuals. This type of reproduction is uncommon among

cyanobacteria, including Oscillatoria.

The asexual reproductive strategies of Oscillatoria enable rapid reproduction and colonization

of new environments. This capability contributes to the formation of large blooms in water

bodies. Hormogone formation is more efficient than fragmentation because hormogonia are

already motile and can actively seek favorable conditions for growth.

Movement in Oscillatoria:

The name Oscillatoria (oscillare, to swing) is given to this alga due to the peculiar movement

shown by the. trichome. It is called ‘oscillatory movement’. These are the pendulum-like

movements of the apical region of the trichome. Some other movements shown by the

trichomes of Oscillatoria are:

a) Gliding or creeping movement: The trichome moves forward and backward along its

long axis.

b) Bending movement: The tip of the trichome shows bending.

Oscillatoria Significance

Oscillatoria holds considerable importance in biology and ecology for several reasons. Here

are the key points:

1. Ecological Role: Oscillatoria, a type of cyanobacteria (blue-green algae), play a vital

role in aquatic ecosystems as primary producers. Through photosynthesis, they help

oxygenate water bodies and facilitate nutrient cycling.

2. Food Source: Certain Oscillatoria species are consumed by various aquatic

organisms like small invertebrates and insect larvae, contributing to the freshwater

food chain dynamics.

3. Nitrogen Fixation: Some Oscillatoria species and other cyanobacteria can convert

atmospheric nitrogen into forms usable by plants and organisms. This process is

crucial for enriching nutrient-poor environments.

4. Environmental Indicators: The presence and abundance of Oscillatoria can indicate

water quality. Excessive growth, often due to nutrient pollution, can lead to harmful

algal blooms (HABs) that degrade water quality and harm aquatic life.

5. Biotechnological Potential: Oscillatoria and other cyanobacteria are studied for their

potential in various biotechnological applications, such as biofuel production,

wastewater treatment, and the production of bioactive compounds.