Difference Between in Biology

Difference Between Endotoxins And Exotoxins


Toxin is produced in the human body or any living organism. It is a poisonous substance that includes proteins, small molecules, peptides. These substances are efficient enough to cause diseases in contact with body tissues or absorption.

Toxins may support in damaging cells trigger immune response and damage, slow down cellular processes. Toxin range varies from minor to immediately deadly. It helps in the pathological process of pathogenic bacteria.

Toxins are further categorized as Endotoxins and Exotoxins. The difference between these toxins depends upon the way of production by bacteria.

Endotoxins are  Lipopolysaccharide-protein complexes (LPS), which is released at the time of cell death of bacteria. It is weekly insusceptible, heat stable. Exotoxins are proteins produced by a few species of bacteria. It is antigenic and heats imbalanced.

The key difference between endotoxins and exotoxins are as follows.

difference between endotoxins and extotoxins

Difference Between Endotoxins And Exotoxins

Character Endotoxins Exotoxins
Definition Endotoxins are the lipopolysaccharide-protein complexes, produced at the time of cell death. Exotoxins are polypeptide proteins excreted by few species of bacteria.
Location It is a part of the cells and located on chromosomal genes. It is released from the cells and located on extrachromosomal genes (e.g. plasmids).
Toxicity Endotoxin is moderate toxic. Exotoxin is highly toxic.
Source It is produced after the disintegration of the gram-negative bacteria. It is produced in the living gram-positive bacteria and gram-negative bacteria.
Molecular Weight The molecular weight is 50-1000 KDa (kilodelton). The molecular weight is 10 KDa (kilodelton).
Heat sensitive It is heat stable and active at 250° C or even at 1000° C. Its is heat imbalanced and destroyed beyond 60-80° C.
Boiling It does not get denatured on boiling. It gets denatured on boiling.
Toxic Conversion It is not possible in endotoxins. It is possible in exotoxins.
Detected It is detected in LAL (limulus amebocyte lysate test. It is detected in various tests like precipitation, neutraliation etc.
Diseases Meningococcemia, sepsis by gram negative rods etc. Botulism, Diphtheria, Tetanus.
Enzymatic Activity The enzymatic activities are always high. Their is no enzymatic activity.
Effects Endotoxins general symptoms are fever, diarrhea, vomiting etc. Exotoxins symptoms are either cytotoxin, enterotoxin or neurotoxin with defined action on cells or tissues.
Neutralization It cannot be neutralized by antibodies. it can be neutralized by antibodies.
Vaccines No effective vaccines are available for endotoxin Effective vaccines are available for exotoxins.
Immunogenicity Endotoxins are weakly immunogenic. Exotoxins are highly immunogenic.
Potency A large amount of toxin is required to cause a disease. A single toxin molecule is enough to cause a disease.
Examples Toxins produced by E.coli, Shigella, Vibrio cholera, Salmonella Typhi. Toxins produced by Staphylococcus aureus, Streptococcus pyogenes, Bacillus anthracis, Bacillus cereus.


The endotoxins are located in the outer membrane of the bacteria. It is recommended as a cell-associated substance responsible for the structure of bacteria. Endotoxins are also known as Lipopolysaccharides or LPS. The LPS are found on the outer surface of the Gram-negative bacteria.

The LPS discharges at the bacterial cell death. In this, the toxicity is related to the lipid component, on the other side immunogenicity is related to polysaccharide components.

The Lipopolysaccharides gives rise to various inflammation and activates complement by the alternative pathway. During the growth of the Gram-negative bacteria, it produces a small amount of endotoxin. Endotoxins play an important role in increasing the natural immunity.


Exotoxins are proteins or polypeptides. It acts at tissue which is away from the original point of bacterial growth. Exotoxins are generally produced by bacteria or with the action of the cell. It is released by bacteria into the surrounding.

Usually, the exotoxins are produced at the growth of the cells of bacteria. The toxin production is specific to a certain family of bacteria that are responsible to produce disease. For example, Corynebacterium diphtheria is responsible to produce diphtheria toxin, Clostridium tetani are responsible to produce tetanus toxins.

These are the poisonous strains of the bacteria responsible for the production of toxins, on the other side nonpoisonous strains are not at all responsible for such productions. Exotoxins are considered to be the most dangerous and toxic substances.


The toxin in bacteria is the most dangerous human poisons and highly active. Now we know about endotoxins and exotoxins and there differences and affections on the animals and their immunity by their chemical nature.





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