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Mycotoxicology is the branch of mycology that focuses on analyzing and studying the toxins produced by fungi, known as mycotoxins.[1] In the food industry it is important to adopt measures that keep mycotoxin levels as low as practicable, especially those that are heat-stable. These chemical compounds are the result of secondary metabolism initiated in response to specific developmental or environmental signals. This includes biological stress from the environment, such as lower nutrients or competition for those available. Under this secondary path the fungus produces a wide array of compounds in order to gain some level of advantage, such as incrementing the efficiency of metabolic processes to gain more energy from less food, or attacking other microorganisms and being able to use their remains as a food source.
Mycotoxins are made by fungi and are toxic to vertebrates and other animal groups in low concentrations. Low-molecular-weight fungal metabolites such as ethanol that are toxic only in high concentrations are not considered mycotoxins. Mushroom poisons are fungal metabolites that can cause disease and death in humans and other animals; they are rather arbitrarily excluded from discussions of mycotoxicology. Molds make mycotoxins; mushrooms and other macroscopic fungi make mushroom poisons. The distinction between a mycotoxin and a mushroom poison is based not only on the size of the producing fungus, but also on human intention. Mycotoxin exposure is almost always accidental. In contrast, with the exception of the victims of a few mycologically accomplished murderers, mushroom poisons are usually ingested by amateur mushroom hunters who have collected, cooked, and eaten what was misidentified as a harmless, edible species.[2]
Mycotoxins are hard to define and are also very difficult to classify. Mycotoxins have diverse chemical structures, biosynthetic origins, myriad biological effects, and produce numerous different fungal species. Classification generally reflects the training of the categorizer and does not adhere to any set system. Mycotoxins are often arranged by physicians depending on what organ they effect. Mycotoxins can be categorized as nephrotoxins, hepatoxins, immunotoxins, neurotoxins, etc. Generic groups created by cell biologist are teratogens, mutagens, allergens, and carcinogens. Organic chemists have attempted to classify them by their chemical structures (e.g., lactones, coumarins); biochemists according to their biosynthetic origins (polyketides, amino acid-derived, etc.); physicians by the illnesses they cause (e.g., St. Anthony's fire, stachybotryotoxicosis), and mycologists by the fungi that produce them (e.g., Aspergillus toxins, Penicillium toxins). None of these classifications is entirely satisfactory. Aflatoxin, for example, is a hepatotoxic, mutagenic, carcinogenic, difuran-containing, polyketide-derived Aspergillus toxin. Zearalenone is a Fusarium metabolite with potent estrogenic activity; hence, in addition to being called (probably erroneously) a mycotoxin, it also has been labeled a phytoestrogen, a mycoestrogen, and a growth promotant.[3]