Endotoxin and exotoxin are the two forms of toxins that the bacteria produce to target other bacteria or host cells. The virulence components of bacteria that alter host cell function are called toxins. It can be used for creating biological weapons. They are often proteins or peptides that are produced by either gram-positive or gram-negative bacteria or microorganisms.
Generally, there are two main categories of toxins, and they are:
Endotoxins (Endo + toxin = cell-associated toxin) are lipopolysaccharides that are secreted by bacteria or other microorganisms and are only released into the environment when they die. It is an essential component for the survival of bacteria.
Endotoxin is a substance found in cells and on chromosomal genes. Compared to exotoxins, they have a modest level of toxicity. Gram-negative bacteria typically produced them. Endotoxin typically ranges in molecular weight from 50 to 1000 kDa. In contrast to exotoxins, they are heat stable and have higher endotoxin enzymatic activity. Fever, vomiting, and diarrhea are just a few of the common symptoms that a person may have from an endotoxin.
An endotoxin has three components; Lipopolysaccharide (LPS): Lipid A moeity, the highly conserved core polysaccharide, and the species-specific O-antigen.
Some examples of endotoxin are E.coli, Shigella, Salmonella typhi, and Vibrio cholerae.
Exotoxins (Exo+ toxin= outside of cell) are polypeptides that bacteria produce in their surroundings. These are usually proteins and act enzymatically or through direct action through the host cells and stimulate a variety of host responses.
Exotoxin is a substance that is typically found on extrachromosomal genes ( plasmids). These are produced by gram-positive bacteria, which makes them extremely toxic and hazardous. They have a molecular weight of roughly 10 KDa, are heat labile, and lack enzymatic activity. Exotoxins are highly immunogenic, filterable, and can be neutralized by antibodies. Moreover, it may play role in invasion. General symptoms shown by them are cytotoxin, neurotoxin, and enterotoxin.
Some examples are Streptococcus pyogenes, Bacillus cereus, and so on.
Difference between Endotoxin and Exotoxin
Below table shows the differences between endotoxin Vs exotoxin:
|Location||It is located on|
|It is generally located on|
|Sources||Produced by gram|
|Produced by gram-positive|
|Structural composition||Generally consisting of|
three elements: lipid A,
and O- specific
|It generally consists of an|
composed primarily of
antiparallel beta structure.
|Thermal stability||Heat stable||Heat labile|
|Enzymatic activity||Enzymatic activity is|
|No Enzymatic activity|
|Toxicity||Moderately toxic||Highly toxic|
|Potency||For toxins to cause diseases,|
a lot of them are needed.
|Numerous host species can|
be affected by a single
|Enzymes present||Catalase, fibrolysin, lgG|
collagenase, nuclease, certain
|Symptoms||Fever, diarrhea, vomiting|
|Cytotoxin, Enterotoxin and|
|Chemical nature||They are composed of|
|They are composed of|
|Resistance||Weakly immunogenic||Highly antigenic|
|Binding properties||Specific receptors not|
|Usually binds to specific|
denatured on boiling.
|Gets denatured on boiling.|
|Tetanus, botulism, etc.|
|Immune response||Immune response is|
|Stronger ability to trigger|
|Conversion capacity||It can’t be converted into|
|It can be converted into|
|Vaccines||No effective vaccines|
|Effective vaccines are available.|
|Examples||E.coli, Vibrio cholerae,|
Salmonella typhi, etc.
|Bacillus cereus, Bacillus|
Published by: Pratiksha Chaudhary (Chemikshya)
Endotoxin and Exotoxin Video
Difference between toxin and poison
Poisons are substances that harm living things when enough of them is absorbed, inhaled, or consumed. A toxic chemical produced by living cells or creatures is referred to as a toxin.
Which is more heat stable, endotoxin or exotoxin?
Endotoxins are heat stable.
Which is highly toxic, endotoxin or exotoxin??
Exotoxins are highly toxic.
Are Exotoxins gram positive or negative?
Exotoxins are gram-positive.
What kind of cell produces endotoxin?
Endotoxin is produced by gram-negative
Is salmonella endotoxin or Exotoxin?
salmonella is enodotoxin.
Size of endotoxin?
The size of endotoxin is 50-1000 kilo Dalton.