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Mycotoxins
1. Mycotoxins are toxic metabolites produced by filamentous fungi under certain environmental conditions that can contaminate foods like cereals, fruits, and vegetables. 2. Major mycotoxins include aflatoxins, ochratoxins, fumonisins, and patulin. Aflatoxins are produced by Aspergillus species and are carcinogenic, while ochratoxins and fumonisins can cause liver and kidney damage. 3. Mycotoxins are detected using extraction and clean-up methods followed by analytical techniques like chromatography, immunoassays, and PCR to identify mycotoxin-producing fungi. Detection methods help ensure food and feed
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Mycotoxins
- 1. Mycotoxins By AbdulrahmanMohammed L-2012-V-21-D
- 2. Contents • Introduction • Types of mycotoxins • Pathogenesis • Signs and symptoms of mycotoxicoses • Methods of detection in food and feed
- 3. Introduction • Mycotoxinsare toxic secondary metabolites produced under appropriate environmental conditions by filamentous fungi species, mainly Aspergillus, Penicillium, Fusarium, Alternaria etc (Zinedine et al., 2007; Oancea and Stoia, 2008 and Turner et al., 2009). • Contamination with mycotoxins has been reported in a large number of commodities, such as cereals, legumes, fruits, vegetables, wine and beer. Mycotoxins exert a broad range of toxic properties (Table 1) and represent an economic and health risk. • Diseases produced by mycotoxins are difficult to diagnose: Very few mycotoxins produce overt signs of poisoning or other symptoms. They are bizarre molecules with molecular weight 50 - >500.
- 4. Introduction… come from: 1. Moisture in crops – inadequate drying 2. Contamination during handling, storage and processing of foods • Such small molecules induce no response in human immune system ! • Major danger of mycotoxin in diet is our inability to detect them biologically
- 5. Types of mycotoxins • Produced by: Aspergillus, Penicillium, Fusarium, Alternaria etc. • Common Members of the Mycotoxin Family are: Aflatoxins Fumonisin Ochratoxins Patulin • Three major genera of molds; Aspergillus, Penicillium, and Fusarium are of significant interest in food safety for production of mycotoxins. • Mold contamination can occur in the field as well as during harvest, processing, transportation and storage. Mycotoxins are highly stable and are difficult to destroy by traditional food processing conditions
- 7. Fungi Substrate Mycotoxin Aspergillus flavus Maize, groundnut, oilseed, cotton seed Aflatoxin Aspergillus parasiticus Maize, groundnut, oilseed, cotton seed Aflatoxin Aspergillus nomius Maize, groundnut, oilseed, cotton seed Aflatoxin Aspergillus ochraceus Barkey wheat Ochratoxin Aspergillus carbonerius Grapes wine coffee Ochratoxin Fusarium oxysporum Wheat barley maize Fumonisins Fusarium sp. Wheat barley maize T-2 toxin Penicillium verrucosum Wheat barley maize Ochratoxin Claviceps purpurea Rye Ergot alkaloids Stachybotrys hay satratoxins
- 9. ROSEANU et al.,2010
- 10. Three generalmechanisms of mycotoxin action are described as mutagenic, teratogenic, or carcinogenic During the mutagenic action, toxin binds to DNA, especially the liver mitochondrial DNA resulting in point mutation addition or substitution in DNA and affect liver function (hence hepatotoxic). Teratogenic action leads to birth defects the carcinogenic effect cause irreversible defects in cell physiology resulting in abnormal cell growth and metastasis. In recent years, the importance of mycotoxins has been highlighted for their potential use as weapon for bioterrorism. Pathogenesis
- 11. Signs and Symptoms • Mycotoxins can cause acute disease manifested by kidney or liver failure or chronic disease including carcinoma, birth defects, skin irritation, neurotoxicity, and death. • Edema of legs and feet • Abdominal pain • Vomit • Acute hepatitis • Convulsion • Cirrhosis • Carcinoma of liver • Fever • Jaundice • Acute necrosis • Malaise
- 12. 1. Aflatoxin Aflatoxinis the name for a group of toxins (poisonous chemical compounds) that are produced by two fungi called Aspergillus flavus and Aspergillus parasiticus.
- 13. Aflatoxin cont.. Fourprimary aflatoxins, named B1, B2, G1 and G2 plus two additional metabolic products, M1 and M2. The case with aflatoxin toxicity and carcinogenicity has been established for aflatoxin - induced mutagenic activity and DNA damage. Aflatoxin (Aspergillus flavus toxin) is produced by Aspergillus flavus and A. parasiticus Aflatoxins occur in different chemical forms; B1,B2, G1, G2, and M1. The allowable toxin limits are 20 ppb in nuts . Allowable limit in meats, corn, and wheat is also 0.5 ppb. The acute lethal dose for adult human is thought to be 10–20 mg. The primary target organ for aflatoxin is the liver.. Aflatoxin causes gross liver damage, resulting in liver cancer (hepatocarcinogen). It can also cause colon and lung cancer. classified aflatoxin B1 as a group I carcinogen.
- 14. Aflatoxicosis Aflatoxicosis isprimarily a hepatic disease.
- 15. Aflatoxin B1 andTumor Induction
- 16. Aflatoxin B1 andTumor Induction
- 17. 2. Ochratoxin Aspergillusochraceus and several other species including Penicillium spp. produce seven structurally related secondary metabolites called ochratoxin Ochratoxin is found in a large variety of foods including wheat, corn, soybeans, oats, barley, coffee beans, meats and cheese. Barley is thought to be the predominant source. Ochratoxin is hepatotoxic and nephrotoxic and a potent carcinogen.
- 18. 3. Fumonosins Fumosinsare produced by Fusarium verticillioides, F. proliferatum, and F. nygamai. Fusarium verticillioides under ideal conditions can infect corn Corns, tomatoes, asparagus, and garlic are the major source of fumonosins. Fumonosins are highly water soluble and they do not have any aromatic Fumonosins are highly stable to a variety of heat and chemical processing treatments. The toxins are reported to cause esophageal cancers in humans.
- 19. 4. Patulin Patulinis produced by Penicillium clariform, P. expansum, P. patulum and by Aspergillus spp. Bread, sausage, fruits (apricots, grapes, peaches, pears, and apples), and apple juice are the major source for this toxin. Patulin is needed in high dosage to show pathogenesis. It is a carcinogenic toxin and is reported to be responsible for subcutaneous sarcoma. The allowable daily intake limit is 0.4 mg kg−1 body weight.
- 20. Mycotoxicosis Severity 1.Type of mycotoxin. 2. Exposure duration and dose. 3. Age. 4. Nutritional status and health of individual. 5. Synergistic effect with other chemicals or mycotoxins. 6. Primary target organs. • liver, lungs, kidney, and nervous, endocrine, immune systems
- 21. Methods of mycotoxindetection in food and feed Analytical procedure for mycotoxin determination
- 22. Methods of mycotoxindetection in food and feed cont…. • The vital step for a right choice of detection procedure is the extraction and clean-up methods to remove the mycotoxins from the type of matrices. • 1.Pretretment methods used: • depend on chemical structures of the mycotoxins and the biological matrix. These include: liquid-liquid extraction (LLE), supercritical fluid extraction (SFE), solid phase extraction (SPE), solid phase microextraction (SIME) etc. • SPE, based on chromatographic columns, is by far the most popular technique currently used for analysis of fumonisin, aflatoxin B1, patulin, ochratoxin in food and feed.
- 23. Methods of detectionin food and feed cont… • 2. Detection methods: CHROMATOGRAPHIC TECHNIQUES • Thin layer chromatography (TLC) • Gas chromatography (GC) • High performance liquid chromatography (HPLC) PHYSICO-CHEMICAL METHODS • Capillary electrophoresis (CE) BIOLOGICAL METHODS • Biosensors IMMUNOLOGICAL METHODS • Immunoaffinity column-based analysis (IAC) or • enzyme-linked immunosorbent assay (ELISA)
- 24. Detection of mycotoxinproducing fungi • 1. Conventional methods • Aspergillus, Penicillium, Fusarium and Alternaria, species that often contaminate foodstuffs and feedstuffs. • Each genus comprises many species. • Identification and enumeration of aflatoxigenic Aspergillus (Bothast and Fennel 1974). • Aspergillus can grow in czapek, sabouraud dextrose or yeast extract sucrose (Difco). • Addition of methyl-b-cyclodextrin (Wacker, Munich) (Fente et al. 2002) or of a combination of methyl-b-cyclodextrin plus bile salts (0.6% Na-deoxycholate) (Rojas-Dura´n et al. 2007) enhances the natural fluorescence of aflatoxins, allowing detection of aflatoxigenic colonies after 3 days (Fente et al. 2002) or 36 h (Rojas-Dura´n et al. 2007a, b) of incubation.
- 25. Detection of mycotoxinproducing fungi cont…. A non-aflatoxigenic strain (a, b) and aflatoxigenic strain (b, c) of A. niger visualized under visible light (a, b) and under 365 nm UV light (c, d). The rim of the white ring around the colony of the aflatoxigenic strain displays faint blue fluorescence (Rojas-Dura´n et al. 2007). With permission of TR Rojas-Dura´n
- 26. Detection of MycotoxigenicFungi by PCR • 1. Aflatoxins. • At least 25 genes are involved in the biosynthesis of AFs and its regulation (Bhatnagar et al. 2006). Primers pertaining to sequences of afl-2, aflD, aflM and aflP, (apa-2, nor-2, ver-2, omt-2, respectively) (Shapira et al. 1996; Geisen 1996; Chen 2002) have been used to detect and identify aflatoxigenic strains of A. flavus and A. parasiticus among isolated colonies, or in DNA extracts from in foodstuff and feedstuff.
- 28. • Other Mycotoxins: • A real-time PCR assay for ochratoxigenic Aspergillus includes primers pertaining to the b-ketosynthase domain of a polyketide synthase from A. carbonarius (Selma et al. 2007). • The PSK4 gene of Fusarium graminearum is involved in the synthesis of fumonisins and can be used to detect Fusaria that produce zearalenone (Lysøe et al. 2006). • PCR methods for the detection of fungi that produce aflatoxins, T2 toxin and DON, fumonisins and patulin (Niessen, 2007) are also available.
- 29. References • M.Rai and A. Varma (eds.), Mycotoxins in Food, Feed and Bioweapons. Pp21- 37.Springer‐Verlag Berlin Heidelberg 2010. • Anca Roseanu, Luiza Jecu, Mihaela Badea, Robert W. Evans. Mycotoxins: An Overview On Their Quantification Methods. ROM. J. BIOCHEM., 47, 1, 79–86 (2010). • Sarah De Saeger(ed). Determining mycotoxins and mycotoxigenic Fungi in food and feed. Pp.427.Wood Head Publishing Limited, Cambrige. 2011. • Hans P. vanEgmond & Walter H. Paulsch. Determination of mycotoxins. Pure &AppI. Chem., Vol. 58, No. 2, pp. 315—326, 1986. • Ludwig Niessen. PCR-based diagnosis and quantification of mycotoxin producing fungi. International Journal of Food Microbiology 119 (2007) 38–46