A Biological Perspective
What is a Mycotoxin?
• Secondary metabolites (chemicals) of a fungus that produce toxic results in another organism.
• Cytotoxic: disrupt cell structures such as membranes, and processes such as protein, DNA, and RNA synthesis.
• Lack of visible appearance of fungus does not negate presence of mycotoxins. Toxins can remain in the organism after fungus has been removed.
• Less selective in organism selection, can cross plant species barrier.
• Can be heat stable, not destroyed by canning or other
Information About Fungus
• Range from single cells to fruiting bodies that form molds, mushrooms, smuts, and yeasts.
• Absorb nutrients from living or deceased organisms, contain no chlorophyll.
• If multicellular, they have tubular filaments called hyphae that branch out.
• Reproduce using spores.
Modes of Spore Transmission
• Airborne, wind or indoor ventilation systems.
• Attachment to insects of birds, thus transmitted from plant to plant, or animal to animal, etc.
• Via transportation mechanisms such as trucks, crop machinery, etc.
• 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.
Conditions to Encourage
• Relative humidity over 70%.
• Temperatures over 30 degrees Celsius for a period of a few days to a week.
• Stress to the affected plant, such as drought, flood, or insect infestation.
• High moisture content of crop (20% or higher).
• Must occur in conjunction, or fungal growth cycle will cease.
Mycotoxin Chain of Events
Locales of Mycotoxins
• In North America, grain producing areas spread from central Canada to the southern parts of the US.
• These grains are then exported to Asia, the Pacific Islands, South and Central America, Europe, the Middle East, India and Africa.
Brief History of Mycotoxins
• Mycotoxin contamination has affected humans for thousands of years.
• In 7th and 8th century, festival for Roman God Robigus, protector of grain and trees was celebrated to stave off rust and mold.
• Middle Ages had outbreaks of ergotism.
• Only in last 30-40 years have scientists been able to isolate specific toxins from their fungal source.
• Research ideas and methodologies, in this field, change frequently, and data from 20 years ago are considered questionable.
• 300-400 mycotoxins presently identified, with more becoming evident as new isolation techniques are used.
• Most frequent toxins present are aflatoxin, DON, ZEN, fumonisin, and T-2 toxin, to name a few.