Toxin-producing fungi

Mycotoxin are toxic metabolites of fungi when ingested by man or animals may cause disease. The most important are trichothecenes, ochratoxin, aflatoxin, and fumonisins. Those mycotoxins are produced by the genera of Fusarium, Aspergillus and Penicillium. They have been found worldwide mainly in cereal grains such as corn, wheat, barley, rye, rice and feedstuff comprised of corned base or cereal products. Trichothecene (TCT) mycotoxins are chemical group of metabolites contains T-2 toxin, HT-2 toxin, diacetoxyscirpenol (DAS), fusarenone x, deoxynivalenol (DON) and nivalenol (NIV) which are all produced by Fusarium fungi. The main toxic effect of TCT appears to be a primary inhibition of protein synthesis followed by a secondary disruption of DNA an RNA synthesis of cells those lining the gastrointestinal tract, skin, and lymphoid cell. Ochratoxin can be produced by several Aspergillus predominant A. alutaceus and Penicillium fungi. Aflatoxins are produced by storage fungi of the genus Aspergillus particularly A. flavus and A. parasiticus. Fumonisins are produced by the group of Fusarium, the most important is F. moniliforme. Some other mycotoxins which are toxic to fowl should be mentioned. Cyclopiazonic acid, the neurotoxin, produced by the genera of Penicillium and Aspergillus. It affects on the central nervous system. Citrinin, produced by Penicillium citrinum, some other species of Penicillium and Aspergillus, has been shown to create servere renal damage in pigs, rats and dogs. Ergot alkaloids contain in the sclerotia of Clavisep spp. Two forms of toxicity in mammals are a gangrenous form with necrosis and sloughing of the extremities and convulsive form characterized by ataxia, tremors and convulsion. Fusarochromanone, isolated from Fusarium equiseti, has been shown to increase the incidence of dyschondroplasia in broilers. Fusaric acid, a phytotoxin, is produced mainly by Fusarium moniliforme. It inhibits one of the enzymes involved in the biosynthesis of norepinephrine. No overt toxicosis in poultry but possible toxic interaction between Fusarium toxins. Moniliformin is also a phytotoxin, produced mainly by strains of F. moniliformin. It is highly toxic for chicken and has been proposed to play a role in the "spiking mortality syndrome" in chicken. Zearalenone, produced by Fusarium roseum, is potent estrogenic properties and can cause vulvovaginitis in young female swine.