Difference Between Endotoxins And Exotoxins

Microbes are found almost everywhere around us, both inside and outside the living organisms. These pathogens produce toxins which are the major causes of the infections. These toxins are categorized into two types:

  • Endotoxins
  • Exotoxins

The basic difference between endotoxins and exotoxins lies in the way how these toxins are produced by bacteria. Let us explore the difference between endotoxins and exotoxins in detail.

Also Read: What are Microbes

Difference Between Endotoxins And Exotoxins

The endotoxins and exotoxins widely vary in toxicity and lethality. Exotoxins are more potent and often fatal when compared to endotoxins. The deadliest toxin in the world – Botulinum toxin or Botox is produced by the bacterium Clostridium botulinum.

The major difference between endotoxins and exotoxins are summarized below:

Endotoxin Exotoxins
The toxin forms a part of the cell wall and is released on the death of the bacteria  The toxin is secreted as a part of metabolism
Endotoxins are composed of a Lipoglycan complex The exotoxin is composed of polypeptides
Its ability to trigger an immune response is comparatively weaker
It has a stronger ability to trigger an immune response
It does not have any enzymatic activity.
Most of the activities are enzymatic in nature.
Moderate toxicity It is highly toxic.
Doe not prove fatal
Often fatal in larger quantities
Cannot be converted into toxoids
Can be made into a Toxoid
Does not get denatured Gets denatured on boiling
Examples of endotoxin-producing bacteria are:

  • Salmonella typhi (Typhoid),
  • Vibrio cholerae (Cholera).
  • Streptococcus pneumoniae (sepsis )

Examples of exotoxin producing bacteria are:

  • Clostridium botulinum (Botox),
  • Clostridium tetani (Tetanus),
  • Corynebacterium diphtheriae (Diphtheria).

Diseases caused by these toxins include:

  • Urinary tract infections
  • Coronary artery disease
  • Meningococcal meningitis

Diseases caused by these toxins include:

  • Scarlet fever
  • Botulism
  • Scalded skin syndrome


These are heat stable proteins or lipopolysaccharides, consisting of a lipid and a polysaccharide that forms primary structural components of the gram-negative bacterial cell wall. These toxins are liberated on the cell’s Lysis. Endotoxins are pyrogens; which are fever causing agents.

Endotoxin, as the name suggests, is the toxin that is liberated from the outer cell wall of a bacteria after its death. These toxins are extremely dangerous to the extent that they can cause severe damage to the organism.


They are heat-labile proteins, mainly secreted by some rare species of bacteria. Once after the toxins are liberated, it diffuses into the surrounding medium and causes harm to the host cells either by disrupting the normal functioning of the cell or by directly destroying the cells. Exotoxins, as the name suggests, are the toxin produced inside the bacteria itself as a part of their metabolism.

Also Read: Difference between gram-positive and gram-negative bacteria

Learn more about Endotoxins, Exotoxins, their differences and other related topics @ BYJU’S Biology.

Frequently Asked Questions

Which bacteria produce endotoxins?

Endotoxins are produced by Shigella, E.coli, Salmonella, Pseudomonas, etc.

Which bacteria produce exotoxins?

Exotoxins are produced by Clostridium botulinum, Clostridium tetani, Corynebacterium diphtheriae, etc.

How do exotoxins and endotoxins cause infections?

The endotoxins release the toxins only when the bacteria is killed, whereas, the exotoxins release toxins immediately into the environment.

Name a few exotoxins.

  • Saxitoxin
  • Tetrodotoxin
  • Eledoisin
  • Conotoxin

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