Bacteria Clostridium botulinum

The most ingenious exocytosis toxins, however, come from the anaerobic bacteria Clostridium botulinum and Clostridium tetani. The former produces the seven botulinum neurotoxins (BoNTs) A-G the latter produces tetanus neurotoxin (TeNT). All eight toxins consist of a heavy (H) chain and a light (L) chain that are associated by an interchain S-S bond. The L-chains enter the cytosol of axon terminals. Importantly, BoNT L-chains mainly enter peripheral cholinergic terminals, whereas the TeNT L-chain mainly enters cerebral and spinal cord GABAergic and glycinergic terminals. The L-chains are the active domains of the toxins. They are zinc-endopeptidases and specifically split the three core proteins of exocytosis, i.e. the SNAREs (Fig. 1 inset). Each ofthe eight toxins splits a... 

Bacteria not only attack teeth but can also make people extremely sick. Therefore, canned food must be specially prepared to prevent the growth of bacteria. This is usually done by boiling or steaming. People who can their own food at home, however, do not have the sophisticated machines that food-canning manufacturers have. Even so, there are other methods that home canners can use to preserve their own food and keep their families safe. For example, high heat can be used to kill the bacteria Clostridium botulinum, which causes one deadly form of food poisoning called botulism. Acidic conditions will also kill C. botulinum. Because the bacteria cannot survive at a pH below 4.5, very acidic foods such as tomatoes, pears, and peaches are safe for home canning. 

Delayed-action paralytic neurotoxins that block the release of acetylcholine causing a symmetric, descending flaccid paralysis of motor and autonomic nerves. Paralysis always begins with the cranial nerves. Toxins are obtained from an anaerobic bacteria (Clostridium botulinum). Toxin A is a white powder or crystalline solid that is readily soluble in water. It is stable for up to 7 days as an aqueous solution. All toxins are destroyed by heat and decompose when exposed to air for more than 12 h. 

Eotuhnum neurotoxins (EoNTs) are perhaps the most lethal toxins known. EoNTs are a set of seven serotypes (A, E, C, D, E, F and G) that are produced almost exclusively by the bacteria Clostridium botulinum. Serotypes C and D are found in birds and non-human mammals. Types A, E, E and F have been implicated in human cases of botuhsm. LD50 values for EoNTs range from 1.1 to 2.5 ng/kg body weight [7]. EoNTs have been associated with a variety of foods, including honey, chili, and hash browns. Isolation of toxins from the suspected food is the current means of diagnosis. 

A. Botulism is caused by a heat-labile neurotoxin (botulin) produced by the bacteria Clostridium botulinum. Different strains of the bacterium produce seven distinct exotoxins A, B, C, D, E, F, and G types A, B, and E are most frequently involved in human disease. Botulin toxin irreversibly binds to cholinergic nerve terminals and prevents acetylcholine release from the axon. Severe muscle weakness results, and death is caused by respiratory failure. The toxin does not cross the blood-brain barrier. 

Plants are not the only organisms that produce such environmentally transmittable toxins. A number of different bacterial species produce exotoxins, which are chemicals that, once secreted, act at a site removed from the bacterial growth. Exotoxins are usually proteins that interact with host cells, producing a wide variety of responses, and most exotoxins act at tissue sites remote from the bacteria that produce them. Many of these exotoxins cause disease, and some well-known and historically devastating diseases, such as botulism, diphtheria, and tetanus, are caused not by the bacteria themselves but rather by the exotoxins that they secrete. A perfect example of this phenomenon are the neurotoxins produced by the bacteria Clostridium botulinum. 

Source of Chemical Bacteria (Clostridium botulinum) Bacteria (Clostridium tetani)... 

The mechanism whereby the bacteria produce the disease with its attendant symptoms is often due to the cells ability to produce specific poisons, toxins or aggressins (Chapter 14). Many of these are tissue-destroying enzymes which can damage the cellular structure ofthe body or destroy red blood cells. Others (neurotoxins) are highly specific poisons ofthe central nervous system, for example the toxin produced by Clostridium botulinum is, weight for weight, one ofthe most poisonous substances known. 

Bacteria, viruses, and rickettsiae have similar symptom progressions in that exposure is followed by a period of reproductive growth (often nonsympto-matic) in the body. As their numbers increase, they often eventually overcome the immune system. Many produce toxins that interfere with bodily functions. Purified toxins such as botulinum toxin (produced by the Clostridium botulinum bacteria) act in a similar manner to chemical agents since, as complex chemical compounds, they do not reproduce but immediately interfere with bodily functions. However, most toxins are not absorbed through the skin, as... 

Botulinum exotoxin impedes release of neurotransmitter vesicles from cholinergic terminals at neuromuscular junctions. Botulinum exotoxin is ingested with food or, in infants, synthesized in situ by anaerobic bacteria that colonize the gut. A characteristic feature of botulinum paralysis is that the maximal force of muscle contraction increases when motor nerve electrical stimulation is repeated at low frequency, a phenomenon attributable to the recruitment of additional cholinergic vesicles with repetitive depolarization of neuromuscular presynaptic terminals. Local administration of Clostridium botulinum exotoxin is now in vogue for its cosmetic effects and is used for relief of spasticity in dystonia and cerebral palsy [21]. 

Rodgers, S., Peiris, P. and Casadei, G., Inhibition of nonproteolytic Clostridium botulinum with lactic acid bacteria and their bacteriocins at refrigeration temperatures, J. Food Prot., 66, 674-678, 2003. 

Food may be contaminated with toxins produced by bacteria, such as botulinum toxin. This is produced by the bacterium Clostridium botulinum and is one of the two most potent toxins known to humans (the other being ricin). As little as one hundred-millionth of a gram (1 X 10-8 g) of the toxin would be lethal for a human. Fortunately, the toxin is destroyed by heat so that cooked food is unlikely to be contaminated (although the bacterial spores are quite resistant). The bacteria grow in the absence of air (they are anaerobic), and consequently, the foodstuffs most likely to be contaminated are those that are bottled or canned and eaten without cooking, for example, raw or lightly cooked fish. 

Botulism A (Clostridium botulinum toxin) Bacteria— food (particularly improperly canned foods), wound, and infantile 1-5 days No Standard Descending muscle paralysis, ptosis (drooping upper eyelids), blurred vision/ diplopia Fatal about 4-6 days nonfatal several months Aggressive resp support, supportive care trivalent and heptavalent antitoxin... 

Bacteria are both harmful and beneficial. They degrade the waste-products produced by society. They are used in wastewater treatment plants— thus, they are beneficial. On the other hand, they can also be pathogenic. The bacteria. Salmonella typhosa, causes typhoid fever Shigella flexneri causes bacillary dysentery. Clostridium tetani excretes toxins producing tetanus. Clostridium botulinum excretes the toxin causing botulism. Corynebacterium diphtheriae is the agent for diphtheria. 

Nitrosamines can be formed when amines that occur naturally in food react with sodium nitrite, NaN02, a preservative added to meats such as ham, bacon, and hot dogs to inhibit the growth of Clostridium botulinum, a bacterium responsible for a lethal form of food poisoning. Nitrosamines may also be formed in vivo in the gastrointestinal tract when bacteria in the body convert nitrates (N03 ) into nitrites (NO2 ), which then react with amines. 

Clostridial neurotoxins are proteins that are produced by the anaerobic bacteria Clostridium tetani (tetanus toxin) and Clostridium botulinum (botulinum neurotoxins). Whereas tetanus toxin (TeTx) comprises a single molecular species, different strains of Clostridium botulinum produce seven different types of botulinum neurotoxin (desig-... 

A-B Toxins are bacterial toxins composed of two peptide chains one (B) that binds to the invaded cell surface, and the other (A) containing the toxin which is then taken-up into the cell. Some examples of exotoxins secreted by the bacteria into the surrounding medium and highly toxic to certain tissues are pathogens causing botuiism (Clostridium botulinum), tetanus (Clostridium tetani) and diptheria (Corynebacterium diphtheria. An example of an A-B endotoxin is Vibrio cholerae. Botulinum toxin and tetanus toxin have their main toxic actions on neuronal tissues, so are described at NEUROTOXINS. 

Lysozyme, which makes up 3.5% of the total egg white proteins and can be easily separated by ion-exchange techniques (Lesnierowski and Kijowski, 2001), is recognized as a safe, antimicrobial agent to be used for food preservation. It is stable up to about 100°C, has maximum activity at a pH range of 5.3-6.4, and inhibits several pathogenic bacteria, including Listeria monocytogenes, Clostridium botulinum, Yersinia enterocolitica, and Campylobacter jejuni (Kijowski and Lesnierowski, 1999). 

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