The main difference between endotoxin, enterotoxin, and exotoxin is that endotoxin is a lipopolysaccharide found in the outer membrane of gram-negative bacteria. However, exotoxin is a protein that is mainly excreted by gram positive bacteria . Average , while, enterotoxin is a type of exotoxin effective on the intestines. In addition, endotoxins and enterotoxins are heat stable, exotoxins, however, at 60 ° C rapidly destroyed. In addition, endotoxins are weak toxins that cause general symptoms, while enterotoxins cause diarrhea and food poisoning. However, exotoxins are highly toxic and often fatal.
In short, endotoxin, enterotoxin, and exotoxin are three types of toxins produced by pathogenic bacteria. And they can be either small or large biomolecules that , upon contact, can cause structural damage, disease, or be absorbed by tissues.
Key areas covered
1. What is an endotoxin - definition, properties, effect 2. What is an exotoxin - definition, properties, effect 3. What is an enterotoxin - definition, properties, effect 4. What are the similarities between endotoxin enterotoxin and exotoxin - overview of Common Features 5. What is the Difference Between End Toxin Enterotoxin and Exotoxin - Main Differences Comparison
key terms
Endotoxin, enterotoxin, exotoxin, pathogenic bacteria, toxoid
What is an endotoxin?
An endotoxin is a lipopolysaccharide (LPS), which is a type of large molecule made up of lipid and polysaccharide. It occurs mainly on the outer membrane of gram-negative bacteria. Also lipooligosaccharides (LOS) are a type of low molecular weight forms of LPS. In addition, the endotoxins on the bacterial cell membrane make a significant contribution to the structural integrity and protect the membrane from chemical attack. They also increase the negative charge on the cell membrane and thus stabilize the membrane structure.
Figure 1: Endotoxins on the cell membrane of gram-negative bacteria
In addition, endotoxins consist of three parts; O-antigen / O-polysaccharide, core oligosaccharide, and lipid A. Of these, O-antigen is a repeating glycan polymer that binds to the core oligosaccharide to form the extracellular domain of the endotoxin. Meanwhile, the core domain comprises either an oligosaccharide or a non-carbohydrate component that binds to lipid A directly. And lipid A is usually a phosphorylated one Glucosamine Disaccharide decorated with several fatty acids . Basically, it binds the endotoxin to the bacterial membrane via the hydrophobic fatty acid chains of lipid A.
What is an exotoxin?
Exotoxin is a type of secretory protein found in gram-positive bacteria and some gram-negative bacteria. It can cause damage to the host cells by disturbing them the normal metabolism of the cell or destroy through directly to the cells. Therefore, they are highly toxic and immunogenic. In addition, their symptoms are fatal. Some examples of exotoxins are the Botulinum toxin produced by Clostridium botulinum, diphtheria toxin produced by Corynebacterium diphtheriae Toxin and tetanospasmin produced by Clostridium tetani . And all three toxins are neurotoxins.
Figure 2: Immune response to exotoxins
In addition, exotoxins are sensitive to heat and can therefore be destroyed by heat. The production of toxoid through chemical treatment is another method of destruction. In this method, the toxoid is the chemically modified form of the toxin that is no longer toxic but is still antigenic. Therefore, it is important as a vaccine with active immunity . In addition, exotoxins are susceptible to antibodies and therefore the body's immune system can develop an immune response against them. In the case of passive immunity , for example, antitoxin or the antiserum with antibodies can be injected.
What is an enterotoxin?
Enterotoxin is also a type of exotoxin. It primarily targets the intestines. In addition, enterotoxins can be encoded either chromosomally or in plasmids. In addition, they are heat stable and are secreted to the outside by several bacteria, including Staphylococcus aureus, Bacillus cereus and Vibrio cholera . In addition, they have a low molecular weight and are water soluble. It is important that E- terotoxins are cytotoxic and therefore they kill epithelial cells in the intestinal wall by changing the permeability of the apical membrane . These are mostly pore-forming toxins (mostly chloride pores) that aggregate pores in cell membranes, causing cell death .
In addition, this pore formation increases the permeability of chloride, which allows chloride ions to enter the intestinal lumen. Consequently, this increases the movement of sodium ions and water into the lumen, leading to secretory diarrhea within a few hours of ingestion of enterotoxins . For example s taphylococcal food poisoning and Bacillus cereus Diarrheal diseases are two common forms of illness caused by enterotoxins. In addition, stomach cramps, diarrhea, vomiting, loss of appetite, fever, and nausea are symptoms of food poisoning, and these symptoms can be life-threatening if left untreated.
Similarities Between Endotoxin Enterotoxin and Exotoxin
- Endotoxin, enterotoxin, and exotoxin are three types of toxins that pathogenic bacteria produce.
- They are virulence factors that support the pathogenicity of bacteria by damaging the host cell.
Difference between endotoxin enterotoxin and exotoxin
definition
Endotoxin refers to a toxin that is present in a bacterial cell and is released when it breaks down. Meanwhile , enterotoxin refers to a toxin that is produced in the gut or affects the gut, such as: Those that cause food poisoning or cholera, and exotoxin refers to a toxin released into its environment by a living bacterial cell.
Type of biomolecules
Endotoxin is a lipopolysaccharide and enterotoxin is a type of exotoxin, while exotoxin is a protein.
Molecular weight
The molecular weight of endotoxins is about 50-1000 kDa, and the molecular weight of enterotoxins is 25-30 kDa, while the molecular weight of exotoxins is about 10 kDa.
structure
Endotoxins consist of three parts; O-antigen / O-polysaccharide, core oligosaccharide, and lipid A. Meanwhile, enterotoxins and exotoxins include two parts; A subunit with catalytic activity and a B subunit for binding to a suitable cell receptor .
Produced by
Endotoxins are found in the outer membrane of Gram-negative bacteria, but Gram-positive bacteria mainly produce enterotoxins and exotoxins.
Appear
Endotoxins are an integral part of the outer cell membrane, but enterotoxins and exotoxins are a type of secretory protein in the environment.
Heat stability
Endotoxins and enterotoxins are heat stable, exotoxins, however, at 60 ° C rapidly destroyed.
Immunogenicity
Endotoxins are weakly immunogenic, but enterotoxins and exotoxins are strongly antigenic.
toxicity
Endotoxins are moderately toxic, but enterotoxins can be serious and potentially fatal, while exotoxins can be fatal.
Symptoms
Endotoxins are pyrogenic. Enterotoxins cause diarrhea and food poisoning. Meanwhile, exotoxins cause life-threatening symptoms.
Specialty
Endotoxins do not have specific receptors, but enterotoxins and exotoxins have specific receptors.
Toxoid production
Toxoid cannot be produced for endotoxins, but toxoids can be produced for both enterotoxins and exotoxins.
Examples
Neisseria spp. and hemophilus spp. Produce endotoxins. Staphylococcus aureus, Bacillus cereus and Vibrio cholera produce enterotoxins. Meanwhile Clostridium botulinum ; Corynebacterium diphtheriae and Clostridium tetani produce exotoxins.
Diseases
Endotoxins cause septic shock, multiple sclerosis , etc. Enterotoxins cause food poisoning and diarrhea. Meanwhile, exotoxins cause tetanus, diphtheria, and botulism.
diploma
Endotoxin is a lipopolysaccharide found on the outer membrane of pathogenic bacteria. Although they are heat stable, they are weakly immunogenic and moderately toxic. They are also pyrogenic. Enterotoxins are a type of exotoxins that work in the intestines and cause food poisoning and diarrhea. They are also heat stable. Exotoxins are proteins from which pathogenic bacteria secrete to their environment. And they are highly antigenic and highly toxic. Hence, they can cause life-threatening symptoms such as tetanus, diphtheria, and botulism. For this reason, the main difference between endotoxin, enterotoxin and exotoxin is their occurrence, immunogenicity and toxicity.
References:
1. Today, Kenneth. "Bacterial Endotoxin." TODAR'S ONLINE TEXTBOOK OF BACTERIOLOGY, available here .2. Pinchuk, Irina V. et al. "Staphylococcal Enterotoxins." Toxins vol. 2.8 (2010): 2177-97. doi: 10.3390 / toxins2082177 3. Rao, Sridhar. "Exotoxins." Microbiology Notes, June 2006, Available here.
Image courtesy:
1. “Gram-negative cell wall” by Jeff Dahl - Own work ( CC BY-SA 4.0 ) via Commons Wikimedia 2. “Immune response to exotoxins” by Ali1195 and Pokéfan95 ( CC BY-SA 4.0 ) via Commons Wikimedia
