Home/ Molecular microbiology/which framework acts favor an invisibility cloak and protects bacteria from being phagocytized?

Capsule is the structure that acts prefer an invisible cloak and helps the bacteria from phagocytosis.

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Characteristics of capsule:

The features of capsule are as follows:

This capsule can be discovered either on gram positive or gram negative bacteria.Capsule is 0.2µm thick viscous layer.Capsule is present external to the cell wall of bacteria.The capsule is different from the cell wall of bacteria.It is normally written of polysaccharide yet occasionally it is composed of glycoproteins.This capsule can’t be washed by making use of alcohol or various other chemicals.This capsule deserve to be stain separately to visualize the bacteria.This capsule can be loosely affix or tightly attach to the cell wall.Bacteria that have actually capsule external to the cell wall is dubbed as encapsulated bacteria.

Complace of capsule:

The capsule complace is various from bacteria to bacteria. Capsule have actually 2% polysaccharide and 98% water. Mostly, capsule is composed of polysaccharide. Polysaccharides are the long chains of carbohydrate. Monomeric subunit is unified to develop lengthy chains of carbohydrate. The glycosidic linkeras are responsible for the binding of different monomeric units. On hydrolysis, they provide the monomeric components that constitute the polysaccharide unit.

Some bacterial capsule is created of glycoproteins. Glycoproteins are the structure in which the amino acids of proteins are attached through the carbohydprice group. Carbohydprice groups affix via the chain of polypeptides by covalently bonding. These oligosaccharides connect through the peptide chains in the time of translation and post-translation alteration.

Some bacteria contain polypeptide D-glutamate capsule. This kind of capsule is existing in Bacillus antharacis. D-glutamate is the alpha amino acid that is synthesize by many kind of living organism. It is non-essential amino acid that can be synthesized by the human body. This D-glutamate creates the capsule of bacteria.

E.coli capsule have peptidoglyhave the right to and also muramic acids units in it. They are tightly packed to the capsule and also don’t permit the stain to adbelow right into capsule.


Capsule is tightly or loosely to the bacteria cell. Capsule performs many kind of attributes in the bacterial cell. Some of the the features of capsule are as follows:

Prevent phagocytosis:

Capsule is virulent in nature. It is responsible for the pathogenesis of bacteria. It invades the immune device and also allows bacteria to develop illness. It prevents the phagocytosis of the cell. Phagocytosis is the procedure in the immune regulation of organize. In this procedure, initially the pathogen have to enter the body and also phagocytosis occurs. Phagocytosis is a crucial procedure that is percreated by phagocytes. Phagocytes phagocytized the pathogens or pposts. When a microorganism is engulfed by a phagocyte, an intracellular vesicle dubbed a phagosome recorded it. Phagosome foffers through lysosome to develop a phagolysosome. Lysosome has many kind of digestive enzymes and also chemicals that produce respiratory burst. It releases cost-free radicals into the phagolysosome that killed the pathogen.

 Capsule has actually many type of methods to stop the phagocytosis.

It remains confined to the surdeals with wbelow the macropheras are inaccessible.It stays in many kind of tissues and surconfront tissue have less availability of macropheras.It provokes the inflammation that doesn’t allow immune mechanism to recognize the pathogen.It inhibits the phagocytosis chemotaxis. For example; streptolysin of Streptococcus pneumoniae inhibits the neutrophils. If neutrophils don’t come, no immune response occurs.It covers the pathogen by the membranes. This membrane helps the bacteria to attack from the immune mechanism. The immune mechanism doesn’t recognize the bacteria bereason it identifies it as self-molecule due to the presence of membrane.


Capsule helps bacteria to affix to the surfaces. Capsule has actually a sticky nature that affix with the surface of host cell. The fruitful attachment is responsible for the advance of illness. Without the attachment, bacteria don’t reason illness. E.g. pneumonia is caused by the capsulated Streptococcus pneumoniae. If the capsule of bacteria removed by utilizing heat or chemical, the non-capsulated bacteria don’t cause condition in the hold.


Capsule is the polysaccharide layer that protects the bacterial cell from harsh setting. It protects the cell from mechanical injury, heat and unfavorable atmosphere. Capsule doesn’t allow water to move external the cell and therefore proccasion cell from desiccation. In heat environment, bacteria water loss and bacteria.


Source of nutrition:

Capsule may provide the source of nutrition for the bacteria. Bacteria might challenge the shortage of nutrient when grow in the atmosphere. When nutrients deplete, the bacteria use capsule as a resource of carbohydprice. It degrades the capsule and also then provided it as a resource of nutrition.

Types of capsule:

There are 2 kinds of capsule that are existing in bacteria. The classification is done by using the thickness of the capsule.


This form of capsule has actually 0.2µm or more thickness. It is thick membrane that can be oboffered through compound microscopic lense.


Capsule has thickness much less than 0.2µm. it is a thin membrane that are visible under Electron microscopic lense only.

Capsule staining:

Capsule can be oboffered by implies of different staining. Staining imparts shade to the bacterial capsule. When shade impart to the capsule, capsule is conveniently determined under microscopic lense. Tright here is different staining that is offered to observe capsule.

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India ink:

India ink is acidic stain that has actually negative charge. Bacterial cell has actually negative charge on their surface. Due to the repulsive forces, India ink can’t permeate into the bacterial cell. India ink imparts black shade to the background because of attrenergetic forces. The capsule shows up as a hollow area in the black background. It is basic way to determine the bacterial capsule.