Infectious diseases such as anthrax, tetanus, gas gangrene, botulism, and pseudomembranous colitis are transmitted to humans by endospores.Gram-positive, Aerobic or Facultative Endospore-forming Bacteria.The endospore survives until a variety of environmental stimuli trigger germination, allowing outgrowth of a single vegetative bacterium.Endospores are quite resistant to high temperatures (including boiling), most disinfectants, low energy radiation, and drying.The completed endospore consists of multiple layers of resistant coats (including a cortex, a spore coat, and sometimes an exosporium) surrounding a nucleoid, some ribosomes, RNA molecules, and enzymes.Under conditions of starvation, a single endospore forms within a bacterium through a process called sporulation, after which the remainder of the bacterium is degraded.The genus Bacillus (an obligate aerobe often living in the soil) and the genus Clostridium (an obligate anaerobe living in the gastrointestinal tract of animals) produce endospores.Endospores are dormant alternate life forms produced by a few genera of bacteria.difficile survive and subsequently germinate and replicate before the microbiota is restored. difficile in check while the endospores of C. Pseudomembranous colitis ( Clostridium difficile) antibiotics destroy the normal microbiota of the intestines that keep the growth of C.Gas gangrene, caused by Clostridium perfringens) endospores enter anaerobic wounds where they germinate and the vegetative bacteria subsequently replicate.Botulism, caused by Clostridium botulinum endospores enter the anaerobic environment of improperly canned food where they germinate and subsequently replicate.Tetanus, caused by Clostridium tetani endospores enter anaerobic wounds where they germinate and the vegetative bacteria subsequently replicate.Anthrax, caused by Bacillus anthracis endospores can be inhaled, ingested, or enter wounds where they germinate and the vegetative bacteria subsequently replicate.Infections transmitted to humans by endospores include: Finally, DNA repair enzymes contained within the endospore are able to repair damaged DNA during germination.Īlthough harmless themselves until they germinate, they are involved in the transmission of some diseases to humans.The cortex may osmotically remove water from the interior of the endospore and the dehydration that results is thought to be very important in the endospore's resistance to heat and radiation.They also function as a carbon and energy source for the development of a vegetative bacterium during germination. Small acid-soluble proteins (SASPs) saturate the endospore's DNA and protect it from heat, drying, chemicals, and radiation.Calcium-dipicolinate, abundant within the endospore, may stabilize and protect the endospore's DNA.The heat resistance of endospores is due to a variety of factors: The impermeability of the spore coat is thought to be responsible for the endospore's resistance to chemicals. Viable endospores of a halophilic (salt-loving) bacterium have also reportedly been isolated from fluid inclusions in salt crystals dating back over 250 million years!īacterial endospores are resistant to antibiotics, most disinfectants, and physical agents such as radiation, boiling, and drying. Viable endospores have reportedly been isolated from the GI tract of a bee embedded in amber between 25 and 40 million years ago.
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