Mycotoxins Lecture 10 PDF

Mycotoxins Introduction Lecture 10 Mohamed Nasr El-Deen Gomaa Professor of Marine Toxicology  What are Mycotoxins? Low molecular weight compounds produced as fungal secondary metabolites that exert toxic effects on animals and human beings. 300-400 compounds are recognized as myco...

Mycotoxins Introduction Lecture 10 Mohamed Nasr El-Deen Gomaa Professor of Marine Toxicology  What are Mycotoxins? Low molecular weight compounds produced as fungal secondary metabolites that exert toxic effects on animals and human beings. 300-400 compounds are recognized as mycotoxins, many received attention as human threats. The commonly occurring one in food and feed are only 20 compounds Those 20 compounds occurred in food at levels and frequency to be of food safety  What are Mycotoxins? Mold (fungi) produce mycotoxins to destroy their microbial competitors. Mycotoxins are associated with human disease (Mycotoxicosis) and cause acute and chronic effects Mycotoxicosis are resulted from ingestion of contaminated foods but airborne contamination is a problem as well  What is a Mycotoxin Lackof visible appearance of fungus does not means the absence of mycotoxins. Toxins can remain in the organism after fungus has been removed. Less selective in organism selection, can cross plant species barrier. Canbe heat stable, not destroyed by canning or other processes.  Mycotoxins: Mechanisms of Toxicity Cytotoxic Bind to DNA and RNA Alters protein synthesis and functions (e.g. enzymes) Oxidative stress (e.g. lipid peroxidation) Depletes antioxidants Alters cell membrane function and transport Potent mitochondrial toxins (numerous mechanisms)  Modes of Spore Transmission Airborne, wind or indoor ventilation systems. Attachment to insects or birds, Thus transmitted from plant to plant, or animal to animal, etc…. Via transportation mechanisms such as trucks, crop machinery, etc.  Fungal Infection Can occur at any stage in crop production. While in the field. During harvesting. While in silage and storage. Spores can lay dormant for months to years, waiting for positive conditions for germination. Mycotoxins Chain of Events  Conditions to Encourage Fungal Growth and Mycotoxins Production Temperatures over 30ºC for a period of a few days to a week. Stress to the affected plant, such as drought, flood, or insect invasion. Relative humidity RH over 70%. (Water) High moisture content of crop (20% or higher). (Water)  Conditions to Encourage Fungal The Growth optimum Water activity a for w mycotoxins production is 0.98. Reduce aw to 0.95 will reduce both fungal growth and mycotoxin production. The lower fungal growth and mycotoxin production will be at aw of 0.93.  Effect of temperature and water activity (aw) on the growth rate of a strain of Fusarium sp. Fungal growth Water activity a  Mycotoxin Health Hazards Generally lower risk in well developed countries due to improved standards of living. High intake of affected product, usually in conjunction with limited amounts of other food sources. Greatest threat comes from long term exposure due to eating spoiled food or meat from animals fed  Symptoms of Mycotoxicosis 1.Drugs and antibiotics are not effective in treatment. 2.The symptoms can be traced to foodstuffs or feed. 3.Testing of said foodstuffs or feed reveals fungal contamination. 4.The symptoms are not transmissible person to person. 5.The degree of toxicity is subject to persons age (more often in very young and very old),  Mycotoxin Effects on Humans Economic loss due to impaired health of stock animals. Economic loss due to stock animals death. Illness: cold/flu-like symptoms can fatigue include: symptoms, diarrhea, sore throats, dermatitis, headaches, immune nose bleeds, suppression,  Human Health Effects of Mycotoxin Exposure Aflatoxicosis (aflatoxin) Aplastic anemia (bone marrow failure) and bleeding (trichothecenes) Acute pulmonary hemorrhage Cancer (aflatoxins) Birth defects Sick Building Syndrome: Living in moldy indoor environments. Itchy eyes, nausea, fatigue, Headache increased respiratory tract infection Difficulty in concentrating  Chronic exposure of mycotoxins Cancer induction Kidney toxicity (nephrotoxicity) Immune suppression Autism Neurotoxicity Depression Type of mycotoxins, producing fungi, contaminated food, and Mycotoxin Producing toxicity Fungi Contaminated Toxicity food s Aflatoxins Ochratoxi ns T-2 Toxin Vomitoxin (Deoxynivalen ol) Zearaleno ne Fumonisin s  Mycotoxin Effects on Animals Feed refusal. Impaired animal health, resulting in reduced production of eggs, milk, weight gain, etc. Metabolites are passed through the milk in cheese, dry milk, and yogurt. Disease. inflammation of sensitive layers of tissue (laminae) inside the animals’ hoof. Thank you