A mycotoxin (from the
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
μύκης , "fungus" and τοξίνη , "toxin") is a
toxic
Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...
secondary metabolite
Secondary metabolites, also called specialised metabolites, toxins, secondary products, or natural products, are organic compounds produced by any lifeform, e.g. bacteria, fungi, animals, or plants, which are not directly involved in the norm ...
produced by organisms of kingdom
Fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
and is capable of causing disease and death in both humans and other animals.
The term 'mycotoxin' is usually reserved for the toxic chemical products produced by fungi that readily colonize crops.
Examples of mycotoxins causing human and animal illness include
aflatoxin
Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, particularly ''Aspergillus'' species. The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, sweetcorn ...
,
citrinin,
fumonisins The fumonisins are a group of mycotoxins derived from ''Fusarium'' and their Liseola section. They have strong structural similarity to sphinganine, the backbone precursor of sphingolipids.
More specifically, it can refer to:
* Fumonisin B1
* ...
,
ochratoxin A
Ochratoxin A—a toxin produced by different ''Aspergillus'' and ''Penicillium'' species — is one of the most-abundant food-contaminating mycotoxins. It is also a frequent contaminant of water-damaged houses and of heating ducts. Human exposure ...
,
patulin
Patulin is an organic compound classified as a polyketide. It is a white powder soluble in acidic water and in organic solvents. It is a lactone that is heat-stable, so it is not destroyed by pasteurization or thermal denaturation.http://www.s ...
,
trichothecenes
The trichothecenes are a large family of chemically related mycotoxins. They are produced by various species of ''Fusarium'', ''Myrothecium'', ''Trichoderma''/''Podostroma'', '' Trichothecium'', ''Cephalosporium'', '' Verticimonosporium'', and '' ...
,
zearalenone
Zearalenone (ZEN), also known as RAL and F-2 mycotoxin, is a potent estrogenic metabolite produced by some ''Fusarium'' and ''Gibberella'' species. Specifically, the ''Gibberella zeae ,'' the fungal species where zearalenone was initially detected, ...
, and
ergot alkaloids
Ergot ( ) or ergot fungi refers to a group of fungi of the genus ''Claviceps''.
The most prominent member of this group is ''Claviceps purpurea'' ("rye ergot fungus"). This fungus grows on rye and related plants, and produces alkaloids that ca ...
such as
ergotamine
Ergotamine, sold under the brand names Cafergot (with caffeine) and Ergomar among others, is an ergopeptine and part of the ergot family of alkaloids; it is structurally and biochemically closely related to ergoline. It possesses structural sim ...
.
One mold species may produce many different mycotoxins, and several species may produce the same mycotoxin.
Production
Most fungi are
aerobic
Aerobic means "requiring air," in which "air" usually means oxygen.
Aerobic may also refer to
* Aerobic exercise, prolonged exercise of moderate intensity
* Aerobics, a form of aerobic exercise
* Aerobic respiration, the aerobic process of cel ...
(use oxygen) and are found almost everywhere in extremely small quantities due to the diminute size of their
spore
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...
s. They consume
organic matter
Organic matter, organic material, or natural organic matter refers to the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have c ...
wherever
humidity
Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present.
Humidity depe ...
and
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied o ...
are sufficient. Where conditions are right, fungi
proliferate into
colonies
In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state'' ...
and mycotoxin levels become high. The reason for the production of mycotoxins is not yet known; they are not necessary for the growth or the development of the fungi. Because mycotoxins weaken the receiving host, they may improve the environment for further fungal proliferation. The production of toxins depends on the surrounding intrinsic and extrinsic environments and these substances vary greatly in their toxicity, depending on the organism infected and its susceptibility, metabolism, and defense mechanisms.
Major groups
Aflatoxin
Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, particularly ''Aspergillus'' species. The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, sweetcorn ...
s are a type of mycotoxin produced by ''
Aspergillus
' () is a genus consisting of several hundred mold species found in various climates worldwide.
''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Miche ...
'' species of fungi, such as ''
A. flavus'' and ''
A. parasiticus''.
The umbrella term aflatoxin refers to four different types of mycotoxins produced, which are B
1, B
2, G
1, and G
2.
Aflatoxin B
1, the most toxic, is a potent
carcinogen
A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substan ...
and has been directly correlated to adverse health effects, such as
liver cancer
Liver cancer (also known as hepatic cancer, primary hepatic cancer, or primary hepatic malignancy) is cancer that starts in the liver. Liver cancer can be primary (starts in liver) or secondary (meaning cancer which has spread from elsewhere to th ...
, in many animal species.
[ Aflatoxins are largely associated with ]commodities
In economics, a commodity is an economic good, usually a resource, that has full or substantial fungibility: that is, the market treats instances of the good as equivalent or nearly so with no regard to who produced them.
The price of a comm ...
produced in the tropics
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
and subtropics
The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° north and ...
, such as cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus ''Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor perce ...
, peanut
The peanut (''Arachis hypogaea''), also known as the groundnut, goober (US), pindar (US) or monkey nut (UK), is a legume crop grown mainly for its edible Seed, seeds. It is widely grown in the tropics and subtropics, important to both small ...
s, spice
A spice is a seed, fruit, root, bark, or other plant substance primarily used for flavoring or coloring food. Spices are distinguished from herbs, which are the leaves, flowers, or stems of plants used for flavoring or as a garnish. Spices a ...
s, pistachio
The pistachio (, ''Pistacia vera''), a member of the cashew family, is a small tree originating from Central Asia and the Middle East. The tree produces seeds that are widely consumed as food.
''Pistacia vera'' is often confused with other sp ...
s, and maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
.[
]Ochratoxin
Ochratoxins are a group of mycotoxins produced by some ''Aspergillus'' species (mainly ''A. ochraceus'' and A. ''carbonarius'', but also by 33% of ''A. niger'' industrial strains) and some ''Penicillium'' species, especially ''P. verrucosum''. ...
is a mycotoxin that comes in three secondary metabolite forms, A, B, and C. All are produced by ''Penicillium
''Penicillium'' () is a genus of ascomycetous fungi that is part of the mycobiome of many species and is of major importance in the natural environment, in food spoilage, and in food and drug production.
Some members of the genus produce pe ...
'' and ''Aspergillus'' species. The three forms differ in that Ochratoxin B (OTB) is a nonchlorinated form of Ochratoxin A (OTA) and that Ochratoxin C (OTC) is an ethyl ester form Ochratoxin A. ''Aspergillus ochraceus'' is found as a contaminant
Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural environment, workplace, etc.
Types of contamination
Wi ...
of a wide range of commodities including beverage
A drink or beverage is a liquid intended for human consumption. In addition to their basic function of satisfying thirst, drinks play important roles in human culture. Common types of drinks include plain drinking water, milk, juice, smoothies a ...
s such as beer and wine. ''Aspergillus carbonarius'' is the main species found on vine fruit, which releases its toxin during the juice making process. OTA has been labeled as a carcinogen and a nephrotoxin, and has been linked to tumors in the human urinary tract, although research in humans is limited by confounding factors
In statistics, a confounder (also confounding variable, confounding factor, extraneous determinant or lurking variable) is a variable that influences both the dependent variable and independent variable, causing a spurious association. Con ...
.[
]Citrinin
Citrinin is a mycotoxin which is often found in food. It is a secondary metabolite produced by fungi that contaminates long-stored food and it causes different toxic effects, like nephrotoxic, hepatotoxic and cytotoxic effects. Citrinin is mainly ...
is a toxin that was first isolated from ''Penicillium citrinum
''Penicillium citrinum'' is an anamorph, mesophilic fungus species of the genus of ''Penicillium'' which produces tanzawaic acid A-D, ACC, Mevastatin, Quinocitrinine A, Quinocitrinine B, and nephrotoxic citrinin. ''Penicillium citrinum'' ...
'', but has been identified in over a dozen species of ''Penicillium'' and several species of ''Aspergillus
' () is a genus consisting of several hundred mold species found in various climates worldwide.
''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Miche ...
''. Some of these species are used to produce human foodstuffs such as cheese (''Penicillium camemberti
''Penicillium camemberti'' is a species of fungus in the genus ''Penicillium''. It is used in the production of Camembert, Brie, Langres, Coulommiers, and Cambozola cheeses, on which colonies of ''P. camemberti'' form a hard, white crust. I ...
''), sake, miso
is a traditional Japanese seasoning. It is a thick paste produced by fermenting soybeans with salt and ''kōji'' (the fungus ''Aspergillus oryzae'') and sometimes rice, barley, seaweed, or other ingredients. It is used for sauces and spread ...
, and soy sauce
Soy sauce (also called simply soy in American English and soya sauce in British English) is a liquid condiment of Chinese origin, traditionally made from a fermented paste of soybeans, roasted grain, brine, and '' Aspergillus oryzae'' or ''Asp ...
(''Aspergillus oryzae
''Aspergillus oryzae'', also known as , is a filamentous fungus (a mold) used in East Asia to saccharify rice, sweet potato, and barley in the making of alcoholic beverages such as ''sake'' and '' shōchū'', and also to ferment soybeans for m ...
''). Citrinin is associated with yellowed rice
Yellowed rice (also yellow rice, Japanese: 黄変米 Ouhenmai) refers to three kinds of rice grains contaminated with different strains of Penicillium fungi—Yellow rice (''P. citreonigrum''), Citrinum yellow rice (''P. citrinum''), and Islandia ...
disease in Japan and acts as a nephrotoxin Nephrotoxicity is toxicity in the kidneys. It is a poisonous effect of some substances, both toxic chemicals and medications, on kidney function. There are various forms, and some drugs may affect kidney function in more than one way. Nephrotoxin ...
in all animal species tested. Although it is associated with many human foods (wheat
Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
, rice
Rice is the seed of the grass species ''Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima
''Oryza glaberrima'', commonly known as African rice, is one of the two domesticated rice species. It was first domesticated and grown i ...
, corn
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
, barley
Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley pr ...
, oat
The oat (''Avena sativa''), sometimes called the common oat, is a species of cereal grain grown for its seed, which is known by the same name (usually in the plural, unlike other cereals and pseudocereals). While oats are suitable for human con ...
s, rye, and food colored with Monascus
''Monascus'' is a genus of mold. Among the known species of this genus, the red-pigmented '' Monascus purpureus'' is among the most important because of its use in the production of certain fermented foods in East Asia, particularly China and ...
pigment) its full significance for human health is unknown. Citrinin can also act synergistically with Ochratoxin A to depress RNA synthesis
Transcription is the process of copying a segment of DNA into RNA. The segments of DNA transcribed into RNA molecules that can encode proteins are said to produce messenger RNA (mRNA). Other segments of DNA are copied into RNA molecules called ...
in murine kidneys.[
]Ergot
Ergot ( ) or ergot fungi refers to a group of fungi of the genus ''Claviceps''.
The most prominent member of this group is ''Claviceps purpurea'' ("rye ergot fungus"). This fungus grows on rye and related plants, and produces alkaloids that ca ...
alkaloids are compounds produced as a toxic mixture of alkaloids in the sclerotia
A sclerotium (; (), is a compact mass of hardened fungal mycelium containing food reserves. One role of sclerotia is to survive environmental extremes. In some higher fungi such as ergot, sclerotia become detached and remain dormant until favor ...
of species of ''Claviceps
Ergot ( ) or ergot fungi refers to a group of fungi of the genus ''Claviceps''.
The most prominent member of this group is ''Claviceps purpurea'' ("rye ergot fungus"). This fungus grows on rye and related plants, and produces alkaloids that ca ...
'', which are common pathogens of various grass species. The ingestion of ergot sclerotia from infected cereals, commonly in the form of bread produced from contaminated flour, causes ergotism
Ergotism (pron. ) is the effect of long-term ergot poisoning, traditionally due to the ingestion of the alkaloids produced by the ''Claviceps purpurea'' fungus—from the Latin "club" or clavus "nail" and for "head", i.e. the purple club-head ...
, the human disease historically known as St. Anthony's Fire. There are two forms of ergotism: gangrenous, affecting blood supply to extremities, and convulsive, affecting the central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...
. Modern methods of grain cleaning have significantly reduced ergotism as a human disease; however, it is still an important veterinary problem. Ergot alkaloids have been used pharmaceutically.[
]Patulin
Patulin is an organic compound classified as a polyketide. It is a white powder soluble in acidic water and in organic solvents. It is a lactone that is heat-stable, so it is not destroyed by pasteurization or thermal denaturation.http://www.s ...
is a toxin produced by the '' P. expansum'', ''Aspergillus'', ''Penicillium'', and ''Paecilomyces
''Paecilomyces'' is a genus of fungi. A number of species in this genus are plant pathogens.
Several of the entomopathogenic species, such as "'' Paecilomyces fumosoroseus''" have now been placed in the genus ''Isaria'': in the order Hypocreale ...
'' fungal species. ''P. expansum'' is especially associated with a range of moldy fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
s and vegetable
Vegetables are parts of plants that are consumed by humans or other animals as food. The original meaning is still commonly used and is applied to plants collectively to refer to all edible plant matter, including the flowers, fruits, stems, ...
s, in particular rotting apples and figs. It is destroyed by the fermentation
Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...
process and so is not found in apple beverages, such as cider
Cider ( ) is an alcoholic beverage made from the fermented juice of apples. Cider is widely available in the United Kingdom (particularly in the West Country) and the Republic of Ireland. The UK has the world's highest per capita consumption, ...
. Although patulin has not been shown to be carcinogenic, it has been reported to damage the immune system
The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...
in animals.[ In 2004, the ]European Community
The European Economic Community (EEC) was a regional organization created by the Treaty of Rome of 1957,Today the largely rewritten treaty continues in force as the ''Treaty on the functioning of the European Union'', as renamed by the Lisbo ...
set limits to the concentrations of patulin in food products. They currently stand at 50 μg/kg in all fruit juice concentrations, at 25 μg/kg in solid apple products used for direct consumption, and at 10 μg/kg for children's apple products, including apple juice.[
]Fusarium
''Fusarium'' is a large genus of filamentous fungi, part of a group often referred to as hyphomycetes, widely distributed in soil and associated with plants. Most species are harmless saprobes, and are relatively abundant members of the soil mi ...
toxins are produced by over 50 species of ''Fusarium'' and have a history of infecting the grain of developing cereals such as wheat
Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
and maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...
. They include a range of mycotoxins, such as: the fumonisins The fumonisins are a group of mycotoxins derived from ''Fusarium'' and their Liseola section. They have strong structural similarity to sphinganine, the backbone precursor of sphingolipids.
More specifically, it can refer to:
* Fumonisin B1
* ...
, which affect the nervous systems of horse
The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million y ...
s and may cause cancer in rodent
Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...
s; the trichothecenes
The trichothecenes are a large family of chemically related mycotoxins. They are produced by various species of ''Fusarium'', ''Myrothecium'', ''Trichoderma''/''Podostroma'', '' Trichothecium'', ''Cephalosporium'', '' Verticimonosporium'', and '' ...
, which are most strongly associated with chronic and fatal toxic effects in animals and humans; and zearalenone
Zearalenone (ZEN), also known as RAL and F-2 mycotoxin, is a potent estrogenic metabolite produced by some ''Fusarium'' and ''Gibberella'' species. Specifically, the ''Gibberella zeae ,'' the fungal species where zearalenone was initially detected, ...
, which is not correlated to any fatal toxic effects in animals or humans. Some of the other major types of ''Fusarium'' toxins include: enniatin
Enniatins are a class of organic chemical compounds found in ''Fusarium'' fungi. They appear in nature as mixtures of cyclic depsipeptides. The main variants are enniatin A, A1, B and B1 together with minor amounts of enniatin C, D, E and F.
The ...
s such as beauvericin
Beauvericin is a depsipeptide with antibiotic and insecticidal effects belonging to the enniatin family. It was isolated from the fungus ''Beauveria bassiana'', but is also produced by several other fungi, including several ''Fusarium'' species; i ...
), butenolide
Butenolides are a class of lactones with a four-carbon heterocyclic ring structure.Joule JA, Mills K. (2000). Heterocyclic Chemistry 4th ed. Blackwell Science Publishing: Oxford, UK They are sometimes considered oxidized derivatives of furan. The ...
, equisetin, and fusarin Fusarins are a class of mycotoxins produced mainly by fungi of the genus ''Fusarium'', which can infect agriculturally important crops such as wheat, barley, oats, rye, and corn. Chemically, they are polyketides that are also derived from amino aci ...
s.
Occurrence
Although various wild mushrooms contain an assortment of poisons that are definitely fungal metabolites causing noteworthy health problems for humans, they are rather arbitrarily excluded from discussions of mycotoxicology. In such cases the distinction is based on the size of the producing fungus and human intention. Mycotoxin exposure is almost always accidental whereas with mushrooms improper identification and ingestion causing mushroom poisoning
Mushroom poisoning is poisoning resulting from the ingestion of mushrooms that contain toxic substances. Its symptoms can vary from slight gastrointestinal discomfort to death in about 10 days. Mushroom toxins are secondary metabolites produced by ...
is commonly the case. Ingestion of misidentified mushrooms containing mycotoxins may result in hallucinations. The cyclopeptide-producing ''Amanita phalloides
''Amanita phalloides'' (), commonly known as the death cap, is a deadly poisonous basidiomycete fungus, one of many in the genus ''Amanita''. Widely distributed across Europe, but now sprouting in other parts of the world, ''A. phalloides ...
'' is well known for its toxic potential and is responsible for approximately 90% of all mushroom fatalities. The other primary mycotoxin groups found in mushrooms include: orellanine
Orellanine or orellanin is a mycotoxin found in a group of mushrooms known as the Orellani of the family Cortinariaceae. Structurally, it is a bipyridine N-oxide compound somewhat related to the herbicide diquat.
History
Orellanine first came ...
, monomethylhydrazine
Monomethylhydrazine (mono-methyl hydrazine, MMH) is a highly toxic, volatile hydrazine derivative with the chemical formula . It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as ...
, disulfiram-like, hallucinogenic indoles, muscarinic, isoxazole, and gastrointestinal (GI)-specific irritants. The bulk of this article is about mycotoxins that are found in microfungi other than poisons from mushrooms or macroscopic fungi.[
]
In indoor environments
Buildings are another source of mycotoxins and people living or working in areas with mold increase their chances of adverse health effects. Molds growing in buildings can be divided into three groups – primary, secondary, and tertiary colonizers. Each group is categorized by the ability to grow at a certain water activity requirement. It has become difficult to identify mycotoxin production by indoor molds for many variables, such as (i) they may be masked as derivatives, (ii) they are poorly documented, and (iii) the fact that they are likely to produce different metabolites on building materials. Some of the mycotoxins in the indoor environment are produced by ''Alternaria
''Alternaria'' is a genus of Deuteromycetes fungi. All species are known as major plant pathogens. They are also common allergens in humans, growing indoors and causing hay fever or hypersensitivity reactions that sometimes lead to asthma. They ...
'', ''Aspergillus
' () is a genus consisting of several hundred mold species found in various climates worldwide.
''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Miche ...
'' (multiple forms), ''Penicillium
''Penicillium'' () is a genus of ascomycetous fungi that is part of the mycobiome of many species and is of major importance in the natural environment, in food spoilage, and in food and drug production.
Some members of the genus produce pe ...
'', and ''Stachybotrys
''Stachybotrys'' () is a genus of molds, hyphomycetes or asexually reproducing, filamentous fungi, now placed in the family Stachybotryaceae. The genus was erected by August Carl Joseph Corda in 1837. Historically, it was considered closely re ...
''. ''Stachybotrys chartarum'' contains a higher number of mycotoxins than other molds grown in the indoor environment and has been associated with allergies and respiratory inflammation. The infestation of ''S. chartarum'' in buildings containing gypsum board, as well as on ceiling tiles, is very common and has recently become a more recognized problem. When gypsum board has been repeatedly introduced to moisture, ''S. chartarum'' grows readily on its cellulose face. This stresses the importance of moisture controls and ventilation within residential homes and other buildings. The negative health effects of mycotoxins are a function of the concentration
In chemistry, concentration is the abundance of a constituent divided by the total volume of a mixture. Several types of mathematical description can be distinguished: '' mass concentration'', ''molar concentration'', ''number concentration'', an ...
, the duration of exposure, and the subject's sensitivities. The concentrations experienced in a normal home, office, or school are often too low to trigger a health response in occupants.
In the 1990s, public concern over mycotoxins increased following multimillion-dollar toxic mold
Mold health issues refer to the harmful health effects of molds ("moulds" in British English) and their mycotoxins. However, recent research has shown these adverse health effects are caused not exclusively by molds, but also other microbial agen ...
settlements. The lawsuits took place after a study by the Center for Disease Control
The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...
(CDC) in Cleveland, Ohio
Cleveland ( ), officially the City of Cleveland, is a city in the U.S. state of Ohio and the county seat of Cuyahoga County. Located in the northeastern part of the state, it is situated along the southern shore of Lake Erie, across the U.S. ...
, reported an association between mycotoxins from ''Stachybotrys'' spores and pulmonary hemorrhage in infants. However, in 2000, based on internal and external reviews of their data, the CDC concluded that because of flaws in their methods, the association was not proven. ''Stachybotrys'' spores in animal studies have been shown to cause lung hemorrhaging, but only at very high concentrations.
One study by the Center of Integrative Toxicology at Michigan State University
Michigan State University (Michigan State, MSU) is a public university, public Land-grant university, land-grant research university in East Lansing, Michigan. It was founded in 1855 as the Agricultural College of the State of Michigan, the fi ...
investigated the causes of Damp Building Related Illness (DBRI). They found that ''Stachybotrys'' is possibly an important contributing factor to DBRI. So far animal models indicate that airway exposure to ''S. chartarum '' can evoke allergic sensitization, inflammation, and cytotoxicity in the upper and lower respiratory tracts. Trichothecene toxicity appears to be an underlying cause of many of these adverse effects. Recent findings indicate that lower doses (studies usually involve high doses) can cause these symptoms.[
Some toxicologists have used the Concentration of No Toxicological Concern (CoNTC) measure to represent the airborne concentration of mycotoxins that are expected to cause no hazard to humans (exposed continuously throughout a 70–yr lifetime). The resulting data of several studies have thus far demonstrated that common exposures to airborne mycotoxins in the built indoor environment are below the CoNTC, however agricultural environments have potential to produce levels greater than the CoNTC.
]
In food
Mycotoxins can appear in the food chain as a result of fungal infection
Fungal infection, also known as mycosis, is disease caused by fungi. Different types are traditionally divided according to the part of the body affected; superficial, subcutaneous, and systemic. Superficial fungal infections include common ti ...
of crop
A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydroponic ...
s, either by being eaten directly by humans or by being used as livestock feed.
In 2004 in Kenya, 125 people died and nearly 200 others required medical treatment after eating aflatoxin
Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, particularly ''Aspergillus'' species. The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, sweetcorn ...
-contaminated maize.
The deaths were mainly associated with homegrown maize that had not been treated with fungicides or properly dried before storage. Due to food shortages at the time, farmers may have been harvesting maize earlier than normal to prevent thefts from their fields, so that the grain had not fully matured and was more susceptible to infection.
Spices are susceptible substrate for growth of mycotoxigenic fungi and mycotoxin production. Red chilli, black pepper, and dry ginger were found to be the most contaminated spices.
Physical methods to prevent growth of mycotoxin‐producing fungi or remove toxins from contaminated food include temperature and humidity control, irradiation
Irradiation is the process by which an object is exposed to radiation. The exposure can originate from various sources, including natural sources. Most frequently the term refers to ionizing radiation, and to a level of radiation that will serve ...
and photodynamic treatment. Mycotoxins can also be removed chemically and biologically using antifungal/anti‐mycotoxins agents and antifungal plant metabolite
In biochemistry, a metabolite is an intermediate or end product of metabolism.
The term is usually used for small molecules. Metabolites have various functions, including fuel, structure, signaling, stimulatory and inhibitory effects on enzymes, c ...
s.
In animal food
Dimorphic fungi
Dimorphic fungi are fungi that can exist in the form of both mold and yeast. This is usually brought about by change in temperature and the fungi are also described as thermally dimorphic fungi. An example is ''Talaromyces marneffei'', a human ...
, which include Blastomyces dermatitidis
''Blastomyces dermatitidis'' is a dimorphic fungus that causes blastomycosis, an invasive and often serious fungal infection found occasionally in humans and other animals. It lives in soil and wet, decaying wood, often in an area close to a wate ...
and Paracoccidioides brasiliensis
''Paracoccidioides brasiliensis'' is a dimorphic fungus and one of the two species that cause paracoccidioidomycosis (the other being ''Paracoccidioides lutzii).'' The fungus has been affiliated with the family Ajellomycetaceae (division Ascomyco ...
, are known causative agents of endemic systemic mycoses
Fungal infection, also known as mycosis, is disease caused by fungi. Different types are traditionally divided according to the part of the body affected; superficial, subcutaneous, and systemic. Superficial fungal infections include common ti ...
.
There were outbreaks of dog food containing aflatoxin
Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, particularly ''Aspergillus'' species. The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, sweetcorn ...
in North America in late 2005 and early 2006, and again in late 2011.
Mycotoxins in animal fodder, particularly silage
Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage p ...
, can decrease the performance of farm animals and potentially kill them. Several mycotoxins reduce milk yield when ingested by dairy cattle
Dairy cattle (also called dairy cows) are cattle bred for the ability to produce large quantities of milk, from which dairy products are made. Dairy cattle generally are of the species ''Bos taurus''.
Historically, little distinction was mad ...
.[
]
In dietary supplements
Contamination of medicinal plants with mycotoxins can contribute to adverse human health problems and therefore represents a special hazard. Numerous natural occurrences of mycotoxins in medicinal plants and herbal medicines have been reported from various countries including Spain, China, Germany, India, Turkey and from the Middle East. In a 2015 analysis of plant-based dietary supplements, the highest mycotoxin concentrations were found in milk thistle
''Silybum marianum'' is a species of thistle. It has various common names including milk thistle, blessed milkthistle, Marian thistle, Mary thistle, Saint Mary's thistle, Mediterranean milk thistle, variegated thistle and Scotch thistle (thou ...
-based supplements, at up to 37 mg/kg.
Health effects
Some of the health effects found in animals and humans include death, identifiable diseases or health problems, weakened immune systems without specificity to a toxin, and as allergens or irritants. Some mycotoxins are harmful to other micro-organisms such as other fungi or even bacteria; penicillin
Penicillins (P, PCN or PEN) are a group of β-lactam antibiotics originally obtained from ''Penicillium'' moulds, principally '' P. chrysogenum'' and '' P. rubens''. Most penicillins in clinical use are synthesised by P. chrysogenum using ...
is one example. It has been suggested that mycotoxins in stored animal feed are the cause of rare phenotypical
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological proper ...
sex changes in hens that causes them to look and act male. Mycotoxins impact on health may be "very hard" and can be categorized in three forms "as mutagenic, carcinogen
A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substan ...
ic, and genotoxic Genotoxicity is the property of chemical agents that damage the genetic information within a cell causing mutations, which may lead to cancer. While genotoxicity is often confused with Mutagen, mutagenicity, all mutagens are genotoxic, but some geno ...
."
In humans
Mycotoxicosis is the term used for poisoning associated with exposures to mycotoxins. Mycotoxins have the potential for both acute and chronic health effects via ingestion, skin contact, inhalation, and entering the blood stream and lymphatic system. They inhibit protein synthesis, damage macrophage
Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer cel ...
systems, inhibit particle clearance of the lung, and increase sensitivity to bacterial endotoxin.[ Testing for mycotoxicosis can be conducted using immunoaffinity columns.
The symptoms of mycotoxicosis depend on the type of mycotoxin; the concentration and length of exposure; as well as age, health, and sex of the exposed individual.][ The synergistic effects associated with several other factors such as genetics, diet, and interactions with other toxins have been poorly studied. Therefore, it is possible that vitamin deficiency, caloric deprivation, excessive alcohol use, and infectious disease status can all have compounded effects with mycotoxins.][
]
Mitigation
Mycotoxins greatly resist decomposition or being broken down in digestion, so they remain in the food chain in meat and dairy products. Even temperature treatments, such as cooking and freezing, do not destroy some mycotoxins.
Removal
In the feed and food industry it has become common practice to add mycotoxin binding agents such as montmorillonite
Montmorillonite is a very soft phyllosilicate group of minerals that form when they precipitate from water solution as microscopic crystals, known as clay. It is named after Montmorillon in France. Montmorillonite, a member of the smectite gro ...
or bentonite
Bentonite () is an absorbent swelling clay consisting mostly of montmorillonite (a type of smectite) which can either be Na-montmorillonite or Ca-montmorillonite. Na-montmorillonite has a considerably greater swelling capacity than Ca-mon ...
clay in order to effectively adsorb the mycotoxins. To reverse the adverse effects of mycotoxins, the following criteria are used to evaluate the functionality of any binding additive:
* Efficacy of active component verified by scientific data
* A low effective inclusion rate
* Stability over a wide pH range
* High capacity to absorb high concentrations of mycotoxins
* High affinity to absorb low concentrations of mycotoxins
* Affirmation of chemical interaction between mycotoxin and adsorbent
* Proven ''in vivo'' data with all major mycotoxins
* Non-toxic, environmentally friendly component
Since not all mycotoxins can be bound to such agents, the latest approach to mycotoxin control is mycotoxin deactivation. By means of enzymes (esterase
An esterase is a hydrolase enzyme that splits esters into an acid and an alcohol in a chemical reaction with water called hydrolysis.
A wide range of different esterases exist that differ in their substrate specificity, their protein structure, ...
, de-epoxidase), yeast
Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitut ...
(''Trichosporon mycotoxinvorans
''Apiotrichum mycotoxinivorans'' (synonym ''Trichosporon mycotoxinivorans'') is a yeast species purportedly useful in the detoxification of various mycotoxins. It was first isolated from the hindgut of the termite ''Mastotermes darwiniensis''. I ...
''), or bacterial strains (Eubacterium
''Eubacterium'' is a genus of Gram-positive bacteria in the family Eubacteriaceae. These bacteria are characterised by a rigid cell wall. They may either be motile or nonmotile. If motile, they have a flagellum
A flagellum (; ) is a hair ...
BBSH 797 developed by Biomin
Biomin is an animal health and nutrition company headquartered in Inzersdorf-Getzersdorf, Austria that develops and produces feed additives and premixes for livestock animals including swine, poultry, dairy and beef cattle as well as aquaculture ...
), mycotoxins can be reduced during pre-harvesting contamination. Other removal methods include physical separation, washing, milling, nixtamalization
Nixtamalization () is a process for the preparation of corn, or other grain, in which the grain is soaked and cooked in an alkaline solution, usually limewater (but sometimes aqueous alkali metal carbonates), washed, and then hulled. The ter ...
, heat-treatment, radiation, extraction with solvents, and the use of chemical or biological agents. Irradiation methods have proven to be effective treatment against mold growth and toxin production.[
]
Regulations
Many international agencies are trying to achieve universal standardization of regulatory limits for mycotoxins. Currently, over 100 countries have regulations regarding mycotoxins in the feed industry, in which 13 mycotoxins or groups of mycotoxins are of concern. The process of assessing a regulated mycotoxin involves a wide array of in-laboratory testing that includes extracting, clean-up columns and separation techniques. Most official regulations and control methods are based on high-performance liquid techniques (e.g., HPLC
High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pa ...
) through international bodies.[ It is implied that any regulations regarding these toxins will be in co-ordinance with any other countries with which a trade agreement exists. Many of the standards for the method performance analysis for mycotoxins is set by the ]European Committee for Standardization
The European Committee for Standardization (CEN, french: Comité Européen de Normalisation) is a public standards organization whose mission is to foster the economy of the European Single Market and the wider European continent in global tr ...
(CEN).[ However, one must take note that scientific risk assessment is commonly influenced by culture and politics, which, in turn, will affect trade regulations of mycotoxins.
Food-based mycotoxins were studied extensively worldwide throughout the 20th century. In Europe, ]statutory
A statute is a formal written enactment of a legislative authority that governs the legal entities of a city, state, or country by way of consent. Typically, statutes command or prohibit something, or declare policy. Statutes are rules made by le ...
levels of a range of mycotoxins permitted in food and animal feed are set by a range of European directives and EC regulations. The U.S. Food and Drug Administration
The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
has regulated and enforced limits on concentrations of mycotoxins in foods and feed industries since 1985. It is through various compliance programs that the FDA monitors these industries to guarantee that mycotoxins are kept at a practical level. These compliance programs sample food products including peanuts and peanut products, tree nuts, corn and corn products, cottonseed, and milk. There is still a lack of sufficient surveillance data on some mycotoxins that occur in the U.S.
See also
*Mold growth, assessment, and remediation
Mold (American English) or mould (British English), also sometimes referred to as mildew, is a fungal growth that develops on wet materials. Mold is a natural part of the environment and plays an important part in nature by breaking down dead o ...
References
External links
Detailed listing and information on all ''Aspergillus'' mycotoxins
Microbiology of Animal Feeds
{{Authority control