Biological Sciences
Mycotoxins
Mycotoxins are toxic compounds produced by certain fungi that can contaminate food crops, posing a health risk to humans and animals. They are commonly found in grains, nuts, and spices, and can cause a range of adverse health effects, including liver damage, cancer, and neurological disorders. Mycotoxin contamination is a significant concern in food safety and agriculture.
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10 Key excerpts on "Mycotoxins"
- R C Ray, O.P. Ward(Authors)
- 2008(Publication Date)
- CRC Press(Publisher)
EÏÏE1 MICROBIAL BIOTECHNOLOGY IN HORTICULTURE—VOL 2 continue during storage if conditions remain favorable to fungal growth. Fungal attacks that are specific to the postharvest phase and are responsible for mycotoxin accumulation in stored crops are also well-known. It must be underlined that the presence of toxigenic fungi does not necessarily imply mycotoxin contamination. By definition, secondary metabolites are compounds whose synthesis is not essential for the survival of producing organisms and, in the case of Mycotoxins, the function(s) of most of these substances, as well as the possible competitive advantage they may confer in the life cycle of respective fungal producers, have not yet been fully explored. Nevertheless, recent evidence points to some of these toxins as aggressiveness factors in the attack on plant tissue by mycotoxin-producing fungal pathogens. This is the case for some of the Mycotoxins produced by Fusarium spp. in cereals (Snijders, 1994). Whatever be the biological/ecological role of Mycotoxins in the biology of their fungal producers, they represent a serious health hazard worldwide, since they reach the consumer's desk as contaminants of plant-derived and animal-derived products, such as eggs, milk, dairy products and meat, as a consequence of feed contamination (Moss, 1996a). Mycotoxins display great chemical diversity and approximately 400 of these fungal metabolites are currently considered to be toxic (Moss, 1996a; Sweeney and Dobson, 1998). They encompass a large and heterogeneous group of substances exhibiting acute, sub-acute, and chronic toxicity in animals and humans. Fungal species that are able to synthesize Mycotoxins are present in all major taxonomic groups. Some of these compounds are carcinogenic, mutagenic and teratogenic. Further, Mycotoxins reduce the quality and acceptability of agricultural products, decrease the nutritional quality of foods and dramatically decrease the viability of plant seeds.
eBook - PDFFood Mycology
A Multifaceted Approach to Fungi and Food
- Jan Dijksterhuis, Robert A. Samson, Jan Dijksterhuis, Robert A. Samson(Authors)
- 2007(Publication Date)
- CRC Press(Publisher)
121 Chapter 7 Why do fungi produce Mycotoxins? Naresh Magan and David Aldred Applied Mycology Group, Biotechnology Centre, Cranfield University, Silsoe, Bedford MK45 4DT, U.K. INTRODUCTION Fungi are ubiquitous in nature and have evolved over time to colonise a wide range of ecosystems. Part of this evolution process has been the development of the ability to produce a range of extracellular chemicals known as secondary metabolites. Many fungi have been responsible for the production of very useful secondary metabolites with pharmaceutical use (e.g., penicillin, cyclosporin, the statin group) as well as those which are considered to be toxic. This group is known collectively as my-cotoxins . Two of these are classed as 2B car-cinogens (aflatoxin, ochratoxin). Others such as the trichothecenes, zearalenone, patulin and fumonisins are important agents in relation to contamination of human food and animal feed. Secondary metabolites may be defined as those products produced by microorganisms (and other “lower” organisms) that are not directly essential for growth (Betina, 1994). They may therefore be further defined as those metabolic products that have no known role in the “internal economy of the producer” (Wil-liams, 1994). This contrasts with primary me-tabolism which may be defined as: “a summa-tion of the interrelated enzyme catalysed reac-tions which are essential to growth by provid-ing energy, synthetic intermediates and key macromolecules” (Betina, 1989). Secondary metabolites, including mycotox-ins, have previously been considered to be somewhat “exotic” and poorly understood chemical substances. An understanding of this enigmatic group of chemicals is especially important in the case of the Mycotoxins, be-cause of the special threat they can pose in the human food production chain.
eBook - ePubFungi
Applications and Management Strategies
- Sunil K. Deshmukh, J. K. Misra, Jalpa P. Tewari, Tamas Papp, Sunil K. Deshmukh, J. K. Misra, Jalpa P. Tewari, Tamas Papp(Authors)
- 2018(Publication Date)
- CRC Press(Publisher)
CHAPTER 14 Mycotoxins: Fungal Secondary Metabolites with Toxic PropertiesP.M. Canoa , O. Puelb and I.P. Oswald*ABSTRACT
Fungi are frequent contaminant of foodstuffs worldwide. According to environmental conditions and their own physiological particularities, they can develop on living plants in the field or during pre-harvest period as well as during storage in case of drying failure or re-moistening. During their evolution, the filamentous fungi have become one of the most important sources of secondary metabolites. Many of these secondary metabolites display properties interesting for pharmaceutical or food industry. But other metabolites, named Mycotoxins, have several detriment effects on both human and animals. The variety of biological activities of fungal secondary metabolites is directly related to the large diversity of these metabolites in terms of chemical structures. This chemodiversity is largely due to the variety of not only “backbone” enzymes like polyketide synthases (PKS), isoprenyl disphosphate synthases, non ribosomal peptide synthetases (NRPS) and dimethylallyltryptophane synthases (DMATS) but also the tailoring enzymes involved in their biosynthesis. Mycotoxins can thus be classified into four main categories: polyketides, terpenes, non ribosomal peptides and hybrids.This chapter presents a detailed overview of some of the most representative Mycotoxins of each of these categories with a special attention to Mycotoxins that are regulated in a great number of countries: aflatoxins, fumonisins, ochratoxins, patulin, zearalenone and trichothecenes. For the non ribosomal peptides category, gliotoxin and ergot alkaloids have been chosen for their relevance in terms of occurrence and toxicity. This chapter includes information on the current understanding of the mechanisms of their toxinogenesis and summarizes their toxicological effects.
- Chandra, Ram(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
The term mycotoxin was coined in 1962 in the aftermath of an unusual veterinary crisis near London, England, during which approximately 100,000 turkey poults died (Blout, 1961 and Forgacs, 1962). When this mysterious turkey X disease was linked to a peanut (groundnut) meal contaminated with secondary metabolites from Aspergillus flavus (aflatoxins), it sensitized scientists to the possibility that other occult mold metabolites might be deadly. Soon, the mycotoxin rubric was extended to include a number of This ebook is exclusively for this university only. Cannot be resold/distributed. previously known fungal toxins (e.g ., the ergot alkaloids), some compounds that had originally been isolated as antibiotics (e.g ., patulin), and a number of new secondary metabolites revealed in screens targeted at mycotoxin discovery (e.g ., ochratoxin A) (Bennett and Klich, 2003). Fungal spoilage of crops can have serious economic consequences and commodities may be contaminated with toxic fungal secondary metabolites known as Mycotoxins. Human exposure to Mycotoxins may result from consumption of plant derived foods that are contaminated with toxins, the carryover of Mycotoxins and their metabolites into animal products such as milk, meat and eggs or exposure to air and dust containing toxins (Jarvis, 2002; CAST, 2003). Human food can be contaminated with Mycotoxins at various stages in the food chain and the three most important genera of mycotoxigenic fungi are Aspergillus, Fusarium and Penicillium . The principal classes of Mycotoxins produced by these genera are: aflatoxins (Aspergillus ), ochratoxins (Aspergillus and Penicillium ) and trichothecenes and fumonisins (Fusarium ). The disease resulting from mycotoxin exposure is a mycotoxicosis (Bryden, 2007). Animal and human health problems related to food products contaminated with toxic metabolites produced by fungal growth have long been recognized.
eBook - PDF- M. Breitenbach, R. Crameri, S. B. Lehrer, T. A. E. Platts-Mills(Authors)
- 2002(Publication Date)
- S. Karger(Publisher)
Biological conver-sion products of Mycotoxins are also called Mycotoxins. Mycotoxins have recently been the subject of many reviews [3–5]. Toxic metabolites produced by mushrooms and yeast are not included in this review and have been reviewed by Chu [4]. In this chapter, a comprehensive review has been provided of the most significant Mycotoxins, their fungal origin and their toxic effects. The reader will hopefully be able to appreciate the diversity of Mycotoxins that have been examined thus far, and will understand the need for research on several of these toxins that exhibit the potential for harmful effects on animals and humans. After cessation of an active growth phase, fungi are known to produce numer-ous organic compounds called secondary metabolites, which are not required for the growth of the producing fungus. Mycotoxins are low-molecular-weight, nonproteinaceous compounds derived primarily from amino acids, shikimic acid or malonyl CoA, and their effect in animals and humans can be significant. Mycotoxins are generally produced in the mycelia of filamentous fungi, but can accumulate in specialized structures of fungi such as conidia or sclerotia as well as in the environment surrounding the organism. Fungal species that produce Mycotoxins are very diverse. However, some Mycotoxins are only produced by a single fungal species or even by specific strains of a fungal species or a number of fungal species. The toxic effects of Mycotoxins are as diverse as the fungal species that make these toxins. Some Mycotoxins have acute toxic effects while others have toxic effects after long-term exposure (chronic effects). Mycotoxicosis Mycotoxins can elicit acute toxic, mutagenic, teratogenic and carcino-genic effects, as well as estrogenic effects on animals.
eBook - PDF- Ivana Dvorackova(Author)
- 1989(Publication Date)
- CRC Press(Publisher)
Chapter 1 Mycotoxins AND HUMAN DISEASES 1 I. HISTORY OF DISEASES DUE TO Mycotoxins IN MAN The history of the role of Mycotoxins in human diseases has been known since the ancient times, but scientific interest and systematic research in Mycotoxins was not aroused until some 25 years ago. Mycotoxins may be defined as toxic compounds produced by certain fungi growing on and contaminating feed and food. Fungi that produce Mycotoxins are usually classified as molds. In defining the role of Mycotoxins in medical science, a difference must be made between fungal metabolites elaborated under laboratory conditions — known as antibiotics — which are toxic to lower forms of life, such as bacteria, and those which occur naturally in the environment and are toxic to higher forms of life, including animals and even man himself. Whereas the discovery of antibiotics 40 years ago brought a remarkable advance in medicine, the naturally occurring Mycotoxins present a great number of socioeconomic, agricultural, and veterinary problems. The worldwide research on Mycotoxins has made remarkable progress in recent years, but there still remain bewilderingly complex problems regarding their involvement in human health, although the health risk of certain fungi for man has been known for a long time. Probably, the first mycotoxicosis to have been recognized in man was ergotism. This has its origin in the ingestion of rye and other grains contaminated with the mold Claviceps purpurea} The first historical report of an epidemic of ergotism is known from Sparta in 450 BC.2During the Middle Ages, the disease was known in Europe as “St. Anthony’s Fire” or the “Holy Fire”, and periodic outbreaks of ergotism resulted in thousands of deaths.
eBook - PDFFood Safety Chemistry
Toxicant Occurrence, Analysis and Mitigation
- Liangli (Lucy) Yu, Shuo Wang, Bao-Guo Sun, Liangli (Lucy) Yu, Shuo Wang, Bao-Guo Sun(Authors)
- 2014(Publication Date)
- CRC Press(Publisher)
The chemical and biochemical mechanisms for mycotoxin formation are also discussed using grains as examples. 10.1 COMMON Mycotoxins IN FOODS Mycotoxins are low-molecular weight toxic secondary metabolites that are pro-duced by fungi, including many important pathogenic and food-spoilage species of Aspergillus , Fusarium , and Penicillium . These toxins have been recognized as causal factors associated with sickness and death among animals and humans. The chemical toxicity and associated diseases, collectively termed mycotoxicoses, indirectly result from the ability of fungi to infect crop species, thereby contami-nating the foods ingested by both livestock and humans. Pathogenesis by the fungi usually occurs either before or after harvest, under preferred growth conditions, such as high moisture and optimal temperature. Seven categories of Mycotoxins that include AFs (AFB1), fumonisins (fumonisin B1 [FB1]), ochratoxins (OTA), zearalenone, DON, T-2 toxin, and citreoviridin affect food safety significantly. Mycotoxins produced by diverse fungi have different chemical structures and dif-ferent pathways metabolized by human and animal, which result in different tox-icities (Figure 10.1). 4 10.1.1 A FLATOXIN AFs are derived from A. flavus , parasitic Aspergillus, and Aspergillus nomius. Under appropriate temperature and humidity conditions, AFs may frequently contaminate improperly stored nuts (especially peanuts), grains, meals, and other foods. Discovered after an outbreak of the Turkey X disease in England in 1960, the naturally occurring AFs were classified as carcinogenic to humans by the World Health Organization’s (WHO) International Agency for Research on Cancer (IARC) (Group 1). 10.1.1.1 Physical and Chemical Characteristics The common structure feature of the four major AFs is a dihydrodifurano or tet-rahydrodifurano group fused to a substituted coumarin group (Figure 10.2). AFs with molecular weights 312–346 and melting points 200–300°C are soluble in
- Hussaini Anthony Makun(Author)
- 2013(Publication Date)
- IntechOpen(Publisher)
Section 2 Public Health Impact of Mycotoxins Chapter 3 © 2013 Omar, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Mycotoxins-Induced Oxidative Stress and Disease Hossam El-Din M. Omar Additional information is available at the end of the chapter http://dx.doi.org/10.5772/51806 1. Introduction Mycotoxins are pharmacologically active mold metabolites produced in a strain-specific way that elicit some complicated toxicological activities [1] . More than 300 secondary metabolites have been identified while only around 30 have true toxic properties [2] . The chemical structures of Mycotoxins vary significantly, but they are low molecular mass organic compounds [3] . Mycotoxins are small and quite stable molecules which are extremely difficult to remove and enter the food and feed chain while keeping their toxic properties [4] . So, the occurrence of Mycotoxins is regulated by legal limits in all developed countries [5] . Mycotoxin contamination of the feed and food is a global problem because more than 25% of world grain production is contaminated by Mycotoxins [6] . The synthesis of Mycotoxins by moulds is genetically determined and closely related to primary metabolic pathways, such as amino acid and fatty acid metabolism. However, the actual toxin production is modulated by environmental factors such as substrate composition and quality, humidity and temperature. The occurrence of Mycotoxins in animal feed exhibits a geographic pattern, for example Aspergillus species meet optimal conditions only in tropical and subtropical regions, whereas Fusarium and Penicillium species are adapted to the moderate climate. Worldwide trade with food and feed commodities results in a wide distribution of contaminated material [7] .
eBook - PDFFruit and Cereal Bioactives
Sources, Chemistry, and Applications
- Özlem Tokuşoğlu, Clifford A Hall III, Özlem Tokusoglu, Clifford A Hall III(Authors)
- 2011(Publication Date)
- CRC Press(Publisher)
253 © 2011 by Taylor & Francis Group, LLC 12 Mycotoxic Bioactives in Cereals and Cereal-Based Foods Anuradha Vegi Introduction Mycotoxic bioactives are secondary metabolites synthesized by toxigenic fungal species. A wide variety of Mycotoxins are produced by various fungi, often a single fungal species can synthesize more than one type of the mycotoxic bioactive under optimal conditions. These fungi and their Mycotoxins pose a seri-ous threat to not only the plant species such as cereals on which they survive and grow, but also are toxic to animal and human health who consume mycotoxin-contaminated cereal-based foods. The detrimental effects of these toxic bioactives to plants and animals have been researched extensively. Some of the toxigenic fungal species and a variety of Mycotoxins that they produce in some cereals and cereal-based foods will be discussed in this chapter. The mycotoxin presence during some cereal-based CONTENTS Introduction ............................................................................................................................................ 253 Mycotoxigenic Fungi in Cereals and Cereal-Based Foods .................................................................... 254 Mycotoxigenic Fusarium Species in Cereals ................................................................................... 254 Mycotoxigenic Aspergillus in Cereals .............................................................................................. 254 Penicillium Species in Cereals .......................................................................................................... 255 Mycotoxins in Cereals and Cereal-Based Foods ................................................................................... 255 Aflatoxins ..........................................................................................................................................
eBook - PDF- (Author)
- 2002(Publication Date)
- Elsevier Science(Publisher)
6.4. Dietary Modification Modifications to diets, such as use of agents for absorption, distribution and metabolism of Mycotoxins, can affect the toxicity of Mycotoxins. Dietary additives including anti-carcinogenic 188 substances [185,186,187] and chemoprotective agents [188,189,190,191,192] have been found to inhibit the carcinogenic effects of aflatoxins in test animals by preventing formation of aflatoxin-DNA adducts [ 193]. Antioxidants such as vitamin C and E reduced the toxic effects of ochratoxin A [194,195], whereas ascorbic acid provided protection against aflatoxins [196]. The toxic effects of ochratoxin have also been reduced by aspartame because it competitively prevents the binding of ochratoxin to serum albumin [197]. The introduction of hydrated sodium calcium aluminasilicates in diets of animals has reduced the toxicity of various Mycotoxins [such as aflatoxins] to animals because these and related compounds (HSCAS or NOVASIL) have a high affinity for Mycotoxins [198,199,200,201,202] that prevents the absorption of Mycotoxins by animals. Other absorbants that have been tested for Mycotoxins such as T-2 toxin included zeolite, bentonite and superactive charcoal. 7. CONCLUSION Mycotoxins are natural products (secondary metabolites) produced by fungi that evoke a toxic response in higher vertibrates and other animals when fed at low concentrations; some Mycotoxins may also be phytotoxic or antimicrobial. Mycotoxins, however, are not grouped with antibiotics, compounds which also may be produced by fungi with microorganisms as the target species. Also, poisonous metabolites produced by mushrooms and yeasts are not included in this group. Mycotoxin production is associated with fungal development, even though, often there is no positive correlation between fungal growth in a commodity and the toxin levels detected in that commodity. Presumably these compounds play some role in the ecology of the fungus, but their function has not been clearly defined.
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