Clostridium characteristics, taxonomy, morphology, habitat

Simon Doyle

Clostridium It is a genus of gram positive bacteria that are widely distributed in many environments on the planet: soil, water, among others. It was discovered in 1880 by Prazmowski.

Many of the bacteria that make up this genus are highly toxic and lethal to humans. This is because they produce toxins that enter the body and wreak havoc on it..

Clostridium cells. Source: See page for author [Public domain], via Wikimedia Commons

Bacteria of this genus are causal agents of several of the diseases that have plagued humanity for years. These include tetanus, botulism, and gas gangrene. All with a very high mortality rate. Clostridium botulinum toxin is among the most toxic and poisonous substances on the planet.

On the other hand, these bacteria can also be used in certain beneficial applications for humanity, such as the use of botox and the treatment of certain diseases that affect the nerves..

Article index

  • 1 Taxonomy
  • 2 Morphology
  • 3 General characteristics
  • 4 Diseases
  • 5 Applications
  • 6 References


The taxonomic classification of the genus Clostridium is the next:

Domain: Bacterium

Division: Firmicutes

Class: Clostridia

Order: Clostridial

Family: Clostridiaceae

Gender: Clostridium


Bacteria belonging to this genus are bacillary in shape, elongated, with edges that can be rounded or straight. They have average measurements of 0.5-2 microns wide and 2-8 microns long.

Depending on the species, there are cells that are longer than others. For example, C. tetani is 2 microns long, while C. perfringes can be 8 microns long..

Some of the species produce spores that are clearly visible and even distort the bacterial morphology. Example of this is the Clostridium tetani. In others, the presence of spores is not so evident (C. perfringes).

The bacterial cell is surrounded by a cell wall that contains a thick layer of peptidoglycan and other components such as teichoic and lipotheichoic acids..

Likewise, taking into account the different species, it may present other protein components that function as receptors during the pathogenesis process..

The cultures formed the bacteria of the genus Clostridium they differ according to species. They can be of irregular edges, of grayish color, with veil. There are species that even present a double halo of hemolysis (C. perfringes) or a weak halo (C. tetani).

General characteristics

They are gram positive

Bacteria belonging to the genus Clostridium They are characterized by having a thick layer of peptidoglycan in their cell wall, like all gram-positive bacteria.

Peptidoglycan has a complex structure that captures and retains Gram's stain particles. This generates that the bacterial cells have, at the end of the process, the characteristic violet color.

They are anaerobic

The gender Clostridium It is made up of organisms that are strictly anaerobic. This means that they do not use the element oxygen to carry out the different metabolic processes..

Now, there are a few that cannot even be in an environment with oxygen, since this element is toxic for them. On the other hand, there are some that are aerotolerant, that is, they can withstand certain very low levels of oxygen..

Produce spores

When bacteria of the genus Clostrididum they are in an environment in which conditions are hostile to them, they produce spores.

The spores that produce the Clostridium They are endospores, that is, they grow inside the bacterial cell. In general, the spores are able to withstand adverse conditions of temperature and pH.

Once conditions become favorable, the spores germinate.


Bacteria belonging to the genus Clostridium they can be found in a large number of environments. Some are part of the normal bacterial flora of the human body, mainly of the skin and gastrointestinal tract..

Likewise, they can also be found in the soil, water and dust..

Some species are pathogenic

The gender Clostridium It is made up of approximately 40 species of bacteria. Of these, some are responsible for causing certain pathologies in humans.

Among the best known are the Clostridium tetani, causing tetanus; the CLaustridium botulinum, that causes botulism and Claustridium perfinges, associated with gas gangrene.

They cannot reduce sulfates

Bacteria of the genus Clostridium they are unable to reduce sulfates to sulfites. This is because the genes to synthesize the enzymes that carry out this process are not found in its DNA..

Produce toxins

Many of the bacterial species that belong to the genus Clostridium synthesize toxins, which are potentially harmful and even fatal to some animals and humans.

Among the species that produce the most lethal toxins are: Clostridium botulinum, Clostridium tetani Y Clostridium perfringens.

Some species are indole positive and some indole negative

Certain bacteria of this genus synthesize the set of tryptophanase enzymes, which can separate the indole group found in the structure of the amino acid tryptophan. Among these we can mention the Clostridium tetani.

On the contrary, there are others that do not synthesize these enzymes, so they cannot degrade tryptophan. Among these are the Clostridium perfringens and the Clostridium difficile.

It is catalase negative

The bacteria that make up the genus Clostridium they do not have the ability to synthesize the enzyme catalase. Therefore, they cannot unfold the hydrogen peroxide molecule in water and oxygen..

Growing conditions

These bacteria require some conditions to grow and develop properly. Regarding temperature, it can be said that they are mesophiles, since their optimum temperature is around 37 ° C. Of course, within the species that make up this genus there are exceptions.

Likewise, these bacteria require an almost neutral pH, the ideal being between 7 and 7.5.


Bacteria of the genus Clostridium they are generally associated with various pathologies in humans. This is due to the spores they generate, which can be ingested, inhaled or acquired through injuries or wounds on the skin..

A very well documented and studied disease is tetanus, caused by the Clostridium tetani. This disease wreaks havoc on the body's muscles, causing involuntary muscle spasms, high fever, and stiffness in certain muscle groups..

Likewise, the Clostridium difficile It is another bacterium of this genus that causes pathologies or diseases in humans. It is responsible for pseudomembranous colitis. This is a disease that affects the large intestine and causes fever, diarrhea, abdominal pain, anorexia and nausea..

On the other hand, the Clostridium perfringens It is the cause of one of the most virulent infections, gas gangrene. This causes skin lesions, blisters, tachycardia, very high fever and a lot of pain.

Botulism is also a disease caused by bacteria of the genus Clostridium (C. tetani). Here the symptoms are fatigue, blurred vision, diarrhea, constipation, among others. Botulism is a pathology in which you have to be very careful and comply with treatment.


Some of the bacteria that make up the genus Clostridium have certain applications at a commercial, ecological and even therapeutic level.

For example, botulinum toxin, produced by Clostridium botulinum, it has long been used in certain therapies and in the cosmetic industry. Thanks to its ability to paralyze muscles, it is used in the treatment of patients with some pathologies such as sequelae from cerebrovascular accidents, hemifacial spasms and dystonia.

Likewise, it is used in cosmetology under the name of botox to eliminate fine lines. This procedure is quite controversial due to the implications it can have for health.

Similarly, the ability of certain bacteria of this genus to produce ethanol has been used in the production of TNT and gunpowder.

In addition, recent studies have shown that some of these bacteria can be used as environmental indicators of contamination. However, these are studies that are still in their infancy, but in view of the results are promising.


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