microbial toxin microbial toxin microbial toxins are toxins produced by micro-organisms, including bacteria, fungi, protozoa, dinoflagellates, and viruses. many microbial toxins promote infection and disease by directly damaging host tissues and by disabling the immune system. endotoxins most commonly refer to the lipopolysaccharide (lps) or lipooligosaccharide (los) that are in the outer plasma membrane of gram-negative bacteria. the botulinum toxin, which is primarily produced by clostridium botulinum and less frequently by other clostridium species, is the most toxic substance known in the world. however, microbial toxins also have important uses in medical science and research. currently, new methods of detecting bacterial toxins are being developed to better isolate and understand these toxin. potential applications of toxin research include combating microbial virulence, the development of novel anticancer drugs and other medicines, and the use of toxins as tools in neurobiology and cellular biology. bacterial bacteria toxins which can be classified as either exotoxins or endotoxins. exotoxins are generated and actively secreted; endotoxins remain part of the bacteria. usually, an endotoxin is part of the bacterial outer membrane, and it is not released until the bacterium is killed by the immune system. the body's response to an endotoxin can involve severe inflammation. in general, the inflammation process is usually considered beneficial to the infected host, but if the reaction is severe enough, it can lead to sepsis. exotoxins are typically proteins with enzymatic activity that interfere with host cells triggering the symptoms associated with the disease. exotoxins are also relatively specific to the bacteria that produce it; for example, diphtheria toxin is only produced by corynebacterium diphtheriae bacteria and is required for the diphtheria disease. some bacterial toxins can be used in the treatment of tumors. endotoxins most commonly refer to the lipopolysaccharide (lps) or lipooligosaccharide (los) that are in the outer plasma membrane of gram-negative bacteria. not all strains of a bacteria species are virulent; there are some strains of corynebacterium diphtheriae that do not produce diphtheria toxin and are considered nonvirulent and nontoxigenic. additional classifications used to describe toxins include enterotoxin, neurotoxin, leukocidin or hemolysin which indicate where in the host’s body the toxin targets. . enterotoxins target the intestines, neurotoxins target neurons, leukocidin target leukocytes (white blood cells), and hemolysins target red blood cells. exotoxin activity can be separated into specific cytotoxic activity or broad cytotoxic activity based on whether the toxin targets specific cell types or various cell types and tissues, respectively. lethal toxins refers to the group of toxins that are the obvious agents responsible for death associated with the infection. toxinosis is pathogenesis caused by the bacterial toxin alone, not necessarily involving bacterial infection (e.g. when the bacteria have died, but have already produced toxin, which are ingested). it can be caused by staphylococcus aureus toxins, for example. clostridial there are over 200 clostridium species in the world that live in mundane places such as soil, water, dust, and even our digestive tracts. some of these species produce harmful toxins such as botulinum toxin and tetanus toxin among others. most clostridium species that do have toxins typically have binary toxins with the first unit involved in getting the toxin into the cell and the second unit cause cellular stress or deformation. clostridial toxins are widespread and aid in the production of many diseases in humans and other organisms. clostridial toxins are known to aid in gastrointestinal diseases and there is a wide range of mechanisms that clostridial toxins take to invade or enter the cell of the host. pore forming bacterial toxins are common and have a very interesting way of entering or invading the host's cell. the mechanism that clostridial toxins follow includes clostridia forming pores and then the pores inserting themselves into the cell membrane of cells. clostridial toxins have the ability to damage or alter the cell membrane damaging the extracellular matrix of the organism. toxin a and toxin b are two toxins produced by clostridium difficile. toxin a and toxin b are glycosyltransferases that cause the antibiotic-associated pseudomembranous colitis and severe diarrhea that characterize disease presentation of c. diff infections. botulinum botulinum neurotoxins (bonts) are the causative agents of the deadly food poisoning disease botulism, and could pose a major biological warfare threat due to their extreme toxicity and ease of production. they also serve as powerful tools to treat an ever expanding list of medical conditions that benefit from its paralytic properties, an example drug with bonts as the active ingredient is botox. they also serve as powerful tools to treat an ever expanding list of medical conditions that benefit from its paralytic properties delivered through localized injections, an example drug with bonts as the active ingredient is botox. botulinum neurotoxins (bonts) are protein neurotoxins that are produced by the bacteria clostridium. bonts are now largely being studied due to their ability to aid in chronic inflammatory diseases such as acne, multiple sclerosis, and for cosmetic purposes tetanus clostridium tetani produces tetanus toxin (tent protein), which leads to a fatal condition known as tetanus in many vertebrates (including humans) and invertebrates. while tetanus toxin is produced from clostridium tetani, a spore forming bacteria found in soil, tetanus is a paralytic disease that is global and commonly affects newborns as well as non-immunized individuals. tetanus enters the body of organisms through wounds or skin breaks and can be found in manure, soil, and dust. tetanus mechanism includes tetanus preventing the transmission of glycine and γ-aminobutyric acid from inhibitory interneurons in the spinal cord, leading to spastic paralysis. glycine is an important amino acid that is essential for adequate nervous system function aiding in cell communication throughout the body. when tetanus toxin enters the body it is taken up by cholinergic nerve endings traveling axonally into the brain and spinal cord, disrupting motor function in individuals. although tetanus is a damaging toxin that has a multitude of symptoms it can be prevented through vaccination. perfringolysin o toxin clostridium perfringens is an anaerobic, gram-positive bacteria that is often found in the large and small intestines of humans and other animals. clostridium perfringens has the ability to reproduce quickly producing toxins relating to the cause of diseases. the pore-forming toxin perfringolysin has the ability to cause gangrene in calves with the presence of alpha toxin. staphylococcal immune evasion proteins from staphylococcus aureus have a significant conservation of protein structures and a range of activities that are all directed at the two key elements of host immunity, complement and neutrophils. these secreted virulence factors assist the bacterium in surviving immune response mechanisms. examples of toxins produced by strains of s. aureus include enterotoxins that cause food-poisoning, exfoliative toxins that cause scalded skin syndrome, and toxic-shock syndrome toxin (tsst) that underlies toxic shock syndrome. these toxin examples are classified as superantigens. multi-drug resistant s. aureus strains also produce alpha toxin, classified as a pore-forming toxin, which can cause abscesses. shiga shiga toxins (stxs), responsible for foodborne illnesses, are a classification of toxins produced by shiga toxin-producing escherichia coli (stec) and shigella dysenteriae serotype 1. stx was first identified in s. dysenteriae and was later found to be produced by certain strains of e. coli. stxs act through inhibiting protein synthesis of infected cells and can be divided into two antigenically different groups: stx/stx1 and stx2. stx1 is immunologically equivalent to stx; however, it received a separate name to distinguish that it's produced by stec not s. dysenteriae. stx2 is produced only by stec and is antigenically different from stx/stx1. the term shiga-like toxins was previously used to further distinguish the shiga toxins produced by e. coli, but nowadays, they are collectively referred to as shiga toxins. within the stec strains, a subgroup classified as enterohemorrhagic e. coli (ehec) represent a class of pathogens with more severe virulence factors in addition to the ability to produce stxs. ehec infections result in more severe diseases of hemorrhagic colitis and hemolytic uremic syndrome. there are around 200 strains of stec, and the wide range of diversity and virulence between them can be partly attributed to phage-mediated horizontal transfer of genetic material. anthrax toxin anthrax disease in humans results from infection with toxin producing bacillus anthracis strains that can be inhaled, ingested in contaminated food or drink, or obtained through breaks in the skin like cuts or scrapes. domestic and wild animals can also be infected via inhalation or ingestion. depending on the route of entry, disease can present initially as inhalation anthrax, cutaneous anthrax, or gastrointestinal anthrax, but eventually will spread throughout the body, resulting in death, if not treated with antibiotics. anthrax toxin is composed of three domains: protective antigen (pa), edema factor (ef), and lethal factor (lf). ef is an adenylate cyclase that targets atp. lf enzyme is a metalloprotease that confers the lethal phenotype associated with anthrax disease. as lf is the agent responsible for the death of infected hosts, it is classified in the group of lethal toxins. diphtheria toxin diphtheria toxin is produced by virulent corynebacterium diphtheriae that infect the mucosal membranes of the throat and nasal cavity causing a gray, thickened lining of the throat, sore throat, weakness, mild fever, swollen glands of the neck, and difficulty breathing. diphtheria toxin is an adp-ribosyltransferase that inhibits protein synthesis which causes the symptoms associated with the disease. diphtheria used to be a leading cause of childhood death until the creation of a vaccine. the diphtheria vaccine contains a diphtheria toxoid, antigenically identical yet inactivated and non-toxic. when the toxoid is introduced to the body in a vaccine, an immune response is mounted without sequelae associated with the toxigenicity. pertussis toxin pertussis toxin is produced by virulent bordetella pertussis and is responsible for the disease of whooping cough, a respiratory disease that can be fatal for infants. the severe, uncontrollable coughing makes it difficult to breathe causing the “whooping” sound that occurs with inhalation. bordetella pertussis targets cilia of the upper respiratory tract which are damaged by the pertussis toxin, an adp-ribosyltransferase that targets g-proteins. cholera toxin cholera, characterized by copious watery diarrhea, is a potentially life-threatening illness transmitted through the fecal-oral route via food or water contaminated with toxigenic vibrio cholerae. v. cholerae targets the intestines and secretes cholera toxin, an exotoxin and potent enterotoxin that acts as an adp-ribosyltransferase targeting g-proteins. this causes an increase in intracellular camp and forces intestinal cells to expel significant amounts of water and electrolytes into the lumen. listeriolysin o toxin listeriolysin o toxin is an exotoxin produced by listeria monocytogenes and is associated with foodborne systemic illness and meningitis. listeriolysin o toxin is classified as a pore-forming toxin that targets host cholesterol cells, inserting a pore into the host cell plasma membrane and permanently disabling cellular functioning. lipopolysaccharides (lps) lipopolysaccharides (lps) produced by gram-negative bacteria are an example of endotoxins. lsp are structural components of the bacteria's outer membrane that only become toxic to the host as a result of the immune system's destruction of the bacteria cell membrane. detection methods in fresh water environments the most prominent natural toxin groups that exist in aquatic environments are mycotoxins, algal toxins, bacterial toxins, and plant toxins (8). these marine biotoxins are dangerous to human health and have been widely studied due to their high potential to bioaccumulate in edible parts of seafood. autotrophic bacteria and algae are unrelated organisms; however, in aquatic environments, they are both primary producers. cyanobacteria are an important autotrophic bacteria in the water food web. explosions of cyanobacteria known as algal blooms can produce toxins harmful to both the ecosystem and human health. these harmful algal blooms are more likely to be produced at a dangerous amount when there is an excess of nutrients, the temperature is 20 °c, there is more light, and calmer waters. eutrophication and other contamination can lead to an environment that promotes cyanobacteria blooms. processes that promote an excess of nutrients, and human activities, such as agricultural runoff and sewage overflows, are primarily responsible. other factors include algal species and grazers being in higher concentrations, allowing for an abundance of cyanobacterial organisms that are associated with the production of toxins. detection of the extent of an algal bloom begins by taking samples of water at various depths and locations in the bloom. solid-phase adsorption toxin tracking (spatt) spatt was introduced in 2004 as a method of monitoring aquatic toxins.