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What’s it? Morphology, Classification, Traits

Clostridium perfringens 01 - HEALTH AND FITNESS

What’s it? Morphology, Classification, Traits

Overview:  What’s Clostridium?

First described in 1880 by Prazmowski, the genus Clostridium consists of a heterogeneous group of micro organism which can be characterised by their rod-like morphology.

Provided that the species on this genus are heterogeneous in nature, they show quite a few phenotypes starting from acidophyles to psychrophiles.

These variations have additionally been recognized of their genetic make-up the place the G+C content material vary from about 21 to 54 p.c. Whereas some species on this genus could look like Gram-negative, Clostridia are usually Gram-positive organisms which can be largely described as spore-forming, anaerobic micro organism.

* Whereas just a few Clostridium species are pathogenic (inflicting human and animal illness) variety of the species are non-pathogenic, a few of which have helpful industrial purposes

* Clostridium strains of medical significance are Gram-positive species. Nevertheless, some could also be Gram variable. See Gram positive and negative page

Among the species labeled beneath the genus Clostridium embody:

  • C. botulinum
  • C. perfringens
  • C. sporogenes
  • C. bifermentans
  • C. leptum
  • C. difficile


The vast majority of Clostridium strains of medical significance are rod-shaped (straight rods or barely curved). As such, they resemble cylindrical rods when seen beneath the microscope. Nevertheless, this isn’t the case with all species/strains of the genus.

Though Gram-positive rods are frequent, among the colonies could have a convex form with just a few having a spherical or irregular form. The ends additionally fluctuate from rounded to pointed ends relying on the pressure.

When seen beneath the microscope (after a culture) strains of Clostridium difficile have been proven to fluctuate in form from brief, thick varieties to massive Gram-positive rods with rounded ends.

Except for C. perfringens, Clostridium species have peritrichous flagella that permit the organisms to maneuver from one location to a different (swim).

In comparison with different flagella constructions, peritrichous flagella challenge from all instructions of the cell which permits the micro organism to maneuver quickly in any route. Endospores, which can be noticed distending from one finish of the bacterial cell could also be oval or spherical in form.

* The flagella of C. difficile has additionally been proven to induce a pro-inflammatory response.

* Sporulation issue and temperature has additionally been proven to trigger morphological adjustments of such species as C. perfringens in cultures.


At present, greater than 200 species and about 5 subspecies belonging to genus Clostridium have been recognized. A majority of those are free residing saprophytes whereas just a few are pathogenic to human beings (e.g, C. botulinum, C. difficile, and C. tetani).

Scientific Classification of Clostridium Species

Kingdom: Micro organism – Like many different forms of micro organism, members of the genus Clostridium are single-celled prokaryotes which can be characterised by the shortage of membrane-bound organelles (nucleus, mitochondria and so forth). This differentiates them from eukaryotic cells which can be well-developed whose nucleus are enclosed inside membranes.

Phylum: Firmicutes – Phylum Firmicutes consists of a various group of organisms most of that are Gram-positive species. Nevertheless, some, like members of sophistication Negativicutes, have been proven to be Gram-negative. Along with phylum Bacteroidetes, Firmicutes makes up about 98 p.c of intestine micro organism.

* This class can also be characterised by low G+C Gram-positive micro organism

Class: Clostridia – It is a massive class composed of rod or spindle-shaped bacterial cells. Members of sophistication Clostridia are anaerobic in nature and will be present in aquatic environments, soil in addition to the human intestine. The vast majority of species are Gram-positive and type spores.

Order: Clostridiales – The order Clostridiales consists of a various (ecologically, phenotypically and physiologically and so forth) group of organisms. As such, it’s composed of each pathogenic and free-living organisms that could be Gram-positive or Gram-negative throughout staining.

Household: Clostridiaceae – Consisting of greater than 30 genera of Firmicutes, members of household Clostridiaceae are anaerobic Gram-positive organisms which can be usually characterised by the truth that they type monospores and comprise meso-diaminopimelic acid of their peptidoglycan. Members of this class have additionally been proven to fluctuate in morphology in cultures.

Genus: Clostridium



Free-Residing Clostridium

Clostridium species are ubiquitous and thus present in varied environments internationally. Oxygen tolerance amongst these species additionally varies significantly with some being strict anaerobes. For that reason, oxygen focus in a given atmosphere will affect the kind of species current.

The vast majority of Clostridium species are saprophytes, which implies that they receive their vitamins from lifeless crops and animals in soil and varied aquatic environments. In these environments, these micro organism break down varied natural issues which in flip contributes to humus soil.

Other than contributing to humus soil, free-living Clostridium present in soil have additionally been proven to play an necessary position in nitrogen fixation. For example, Clostridium pasteurianum, a free-living Clostridium species is ready to repair atmospheric nitrogen and convert carbohydrates to different compounds and molecules like carbon-dioxide, acetate, and butyrate. Given {that a}  majority of those species are anaerobes, they obtain this by fermentation.

Among the different species of genus Clostridium able to nitrogen fixation embody:

  • C. beijerinkii
  • C. acebutylicum

* Free-living Clostridium species able to fixing nitrogen have the nif gene. 

* Other than soil and water (freshwater sediments), free-living Clostridium species will also be present in varied moist environments corresponding to sure plant roots.

* Among the species present in plant’s roots trigger hurt to the plant. For example, C. puniceum is accountable for potato mushy rot.

In Human and Animal Our bodies 

Whereas among the Clostridium species will be present in soil and aquatic environments, others will be present in human and animal our bodies.

C. perfringens, frequent in nature, can infect people and has been present in such organs because the gall bladder. Different species corresponding to C. difficile have been recognized within the gastrointestinal tract of mammals the place they trigger a spread of infections.

Such species as C. septicum and C. histolyticum have been proven to contaminate the physique by wounds inflicting fuel gangrene. A lot of such species are opportunistic in nature and had been significantly prevalent in circumstances of battlefield accidents.

Fuel Gangrene – Also called clostridial myonecrosis, is a illness that impacts muscle tissue. Right here, the micro organism (C. perfringens) enters the mushy tissue by open wound adopted by native development. Nevertheless, this solely happens beneath anaerobic circumstances (the place blood provide to the affected half is impaired).

This development and unfold of the micro organism into the opposite cells, nonetheless, is restricted because of the presence of oxygen. In circumstances the place the micro organism unfold to close by cells and hinder an inflammatory response by phagocytosis, infections of the cells (and tissue) continues permitting fuel gangrene to develop. Right here, the illness can unfold to wholesome cells over time thus affecting the whole limb.

Metabolic Properties 

Clostridium species fluctuate significantly in the case of oxygen tolerance. Whereas among the species can tolerate some degree of oxygen of their atmosphere, others are strict anaerobes and thus thrive in environments with little or no oxygen focus.

Strict Obligate Anaerobes

Whereas species like C. perfringes and C. Clostridium are obligate anaerobes, others like C. Novyi (kind A) and C. haemolyticum are very strict obligate anaerobes. As such, they can’t survive in regular atmospheric focus of oxygen. Nevertheless, all obligate anaerobes can solely survive and thrive in circumstances of excessive lowering depth with very low oxygen focus.


Though they don’t use oxygen for respiration, some Clostridium species can tolerate it of their atmosphere. This consists of such species as C. carnis, C. tertium, C. and histolyticum.


The genus Clostridium consists of quite a few toxin-producing species. These toxins fluctuate between the species and have totally different impacts on human beings and animals.

Clostridial toxins embody:


Neurotoxins are produced by two Clostridium species specifically, Clostridium tetani (tetanus toxin) and Clostridium botulinum (botulinum toxin). The 2 toxins share a number of options together with heavy H and light-weight L chains which can be sure by a disulfide bond.

Botulinum Toxin (BoNT)

Produced by C. botulinum, Botulinum toxin (BoNT) is a toxic substance that works by binding to nerve endings (cholinergic nerve terminals). In doing so, the toxin blocks the discharge of neurotransmitter acetylcholine thus affecting muscle contraction.

Throughout the nervous system, the neurotransmitter is the first neurotransmitter that sends alerts to cells thus contributing to the contraction of the graceful muscle in addition to the dilation of blood vessels.

By blocking the discharge of this neurotransmitter, muscle contraction is affected, which ends up in muscle weak point and paralysis.

* The toxin could also be launched by intestinal micro organism spores (C. botulinum) or ingested (canned meals and so forth).

There are a number of forms of toxins (BoNT) that embody: A, B, E, F, C, C1, and C2.

Tetanus Toxin (TeNT)

Tetanus toxin is launched by Clostridium tetani and is the first reason behind tetanus.

Usually, spores of the micro organism (C. tetani) enter the physique by wounds on the epidermal and dermal layers. As soon as within the physique, the spore begins to germinate adopted by the discharge of poisons into the bloodstream in addition to the lymphatic system.

From the bloodstream and lymphatic methods, the toxin is taken up by decrease motor neurons and transported to the spinal twine or the brainstem.

Though the toxin impacts the central nervous system on a number of factors, it considerably impacts the neurotransmitter by blocking its launch on the central inhibitory interneurons. In flip, this ends in the disinhibition of the decrease motor neurons which results in uncontrollable contraction of muscle tissues.

* C. tetani spores germinate within the physique beneath anaerobic circumstances

Among the signs of tetanus (Tetanus toxin) embody:

  • Rigidity or muscle spasms (hyperactivity of muscle tissues)
  • Lockjaw
  • Respiratory failure (because of muscle spasm/rigidity)
  • Normal muscle ache
  • Neuronal inactivation
  • Tachycardia


Enterotoxin, a toxin launched by C. perfringens is among the primary causes of gastrointestinal sickness.

Whereas the micro organism produces a number of forms of the toxin (A, B, C, D, E), Kind A (and Kind C in some circumstances) is the one toxin that’s accountable for human sickness.

Within the physique (in vivo) the toxin is launched throughout bacterial sporulation. The toxin is launched into the intestinal lumen the place it binds to the claudin receptors. This ends in the formation of pre-pores and consequently practical pores (CH-1 pore) that trigger oncosis by calcium inflow. 

Among the different toxins launched by Clostridium micro organism embody:

  • Ldl cholesterol-dependent Cytolysins – This toxin is launched by among the Gram-positive Clostridium. As soon as launched, the toxin bind to focus on cells and trigger pore formation.
  • Binary Bacterial Toxins – This toxin is launched by quite a few Clostridium micro organism together with C. perfringens, C. spiroforme  and C. botulinum. Via its mode of motion (synergistic binary mechanism) the toxin causes intoxication and destruction of eukaryotic cells. 

Amongst Clostridium, a majority are Gram-positive rods. For example, C. difficile, related to gastrointestinal sickness, is among the Gram-positive Clostridium that may seem darkish blue/violet having retained the first stain (crystal violet) of their thick peptidoglycan layer.

Though these micro organism could seem Gram-positive, they’ll lose this look beneath varied circumstances. In circumstances of prolonged incubation, among the Clostridium species have been proven to lose their Gram-positive look. A couple of species, nonetheless, have been proven to be Gram-negative and can stain pink throughout Gram staining.


Right this moment, nicely over 200 species belonging to the genus Clostridium have been recognized. Of those, at the least 30 are of scientific significance.

To look at and establish the species, Gram staining method can be utilized.


  • A clean glass slide
  • Gram stains (Crystal violet, Gram’s iodine, Counterstain (safranin) and a decolorizing agent)
  • Pattern – Pattern from a affected person or tradition. (If a pattern from a tradition is used, it mustn’t have been incubated for lengthy).
  • Water (distilled or faucet water)
  • Staining rack
  • Immersion oil
  • Bunsen burner


  • Utilizing a cotton swab, make a smear of the pattern on the central a part of the slide – Use a round movement to make smear
  • Go the slide over the Bunsen burner flame for about 3 occasions to heat-fix the smear – keep away from overheating
  • Place the slide on the staining rack and thoroughly flood with crystal violet – Permit to face for about one minute
  • Tilt the slide and gently rinse with water
  • Flood the slide with Gram’s iodine and permit to face for about 1 minute – Then tilt and rinse with water
  • Tilt the slide and decolorize utilizing acetone (or 95 p.c ethyl alcohol) – To do that, apply the decolorizer drop by drop for about 5 seconds so as to keep away from extreme decolorization
  • Rinse the slide with water instantly after which flood the slide with the counterstain (safranin) for about 1 minute
  • Tilt the slide and rinse with faucet water
  • Rinse extra water utilizing a blotting paper

Place the slide beneath the microscope and consider beneath immersion oil – compound light microscope or phase-contrast microscope could also be used to view the cells.

When seen beneath the microscope, one could observe the next, relying on the species:

C. tetani – They’ll seem purple in shade with attainable terminal spores. They could even be motile relying on the pattern and pattern preparation. College students can even discover that they’re rod-shaped.

C. perfringens –  Below the microscope, this explicit species could seem as both elongated rods or shorter in size. They’re additionally non-motile with no terminal poles. 

See additionally pages on heterotrophs, and extra on unicellular organisms

Return to learning about Bacteria under the Microscope

Return to Prokaryotes Main Page

Return from learning about Clostridium to MicroscopeMaster Home


Bjørnar Hassel. (2013). Tetanus: Pathophysiology, Therapy, and the Chance of Utilizing Botulinum Toxin towards Tetanus-Induced Rigidity and Spasms. Toxins 2013.  

Paul A. Lawson  and Fred A. Rainey (2016). Proposal to limit the genus Clostridium

Prazmowski to Clostridium butyricum and associated species. Worldwide Journal of Systematic and Evolutionary Microbiology (2016). 

Sabina M. Num and Nicodemus M. Useh. (2014). Clostridium: Pathogenic Roles, Industrial Makes use of and Medicinal Prospects of Pure Merchandise as Ameliorative Brokers towards Pathogenic Species. Jordan Journal of Organic Sciences. 

Public Well being England. (2015) .UK Requirements for Microbiology Investigations Identification of Clostridium species 



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