BioProject

Clostridium. This genus comprises about 150 metabolically diverse species of anaerobes that are ubiquitous in virtually all anoxic habitats where organic compounds are present, including soils, aquatic sediments and the intestinal tracts of animals and humans. More...

Clostridium. This genus comprises about 150 metabolically diverse species of anaerobes that are ubiquitous in virtually all anoxic habitats where organic compounds are present, including soils, aquatic sediments and the intestinal tracts of animals and humans. Characteristic of clostridia is the shape of their cells that resembles a drumstick or spindle ('kloster' is Greek for 'spindle'). This shape is attributed to the presence of endospores that develop under conditions unfavorable for vegetative growth and distend single cells terminally or sub-terminally. The endospores of many species are extremely sturdy and survive extended boiling in water and exposure to air. Spores germinate under conditions favorable for vegetative growth, such as anaerobiosis and presence of organic substrates. From the evolutionary perspective, clostridia are considered to be the most ancient bacteria. It is believed that present day Mollicutes (Eubacteria) have evolved regressively (i.e., by genome reduction) from gram-positive clostridia-like ancestors with a low GC content in DNA. Several species of clostridia (e.g., C. perfringens, C. botulinum, C. tetani) are known opportunistic toxin-producing pathogens in animals and humans. Some species are capable of producing organic solvents (acetone, ethanol, etc,), molecular hydrogen and other useful compounds. There are also species that can fix molecular nitrogen and thus are important participants in biological turnaround of nitrogen compounds in nature.

Clostridium perfringens. This organism is a causative agent of a wide spectrum of necrotic enterotoxicoses. In humans it is responsible for such diseases as gas gangrene (clostridial myonecrosis), food poisoning, necrotizing enterocolitis of infants and enteritis necroticans (pigbel). It also causes such animal diseases as lamb dysentery, ovine enterotoxemia (struck), pulpy kidney disease in lambs and other enterotoxemias in lambs and calves.

The bacterium is one of the most widely distributed pathogens in nature. It is commonly found in the environment (soil, sewage) and in the animal and human gastrointestinal tract as a member of the normal microflora. It is a fast growing (generation time 8-10 min) anaerobic flesh-eater. Active fermentative growth is accompanied by profuse generation of molecular hydrogen and carbon dioxide. Unlike most other clostridia, C. perfringens is non-motile. It is also oxygen tolerant which makes it an easy object to work with in laboratories. Systems for genetic manipulation of C. perfringens have been developed and the species became a model organism in clostridial genetic studies.

Known isolates belong to five distinct types (A, B, C, D, and E) that are distinguished based on the specific extracellular toxins they produce. Each of the toxins is responsible for a specific disease syndrome. Type A strains that cause gas gangrene produce toxin alpha (phospholypase C), theta (hemolysin), kappa (collagenase), mu (hyaluronidase), nu (DNAse) and neuraminidase which are all the enzymatic factors aiding the bacterium in invading and destruction of the host tissues.

Clostridium perfringens str. 13. This strain is a type A isolate from the soil. It can establish gas gangrene in a murine experimental model.

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