“(Un)Friendly Fungi and Resourceful Yeasts”
Contributed by Isabel Warner
You’d think fungi would be fun-guys, but many of our moldy friends don’t have our best interests at heart. That is, if they had a heart.
Some particularly un-fun fungi-s include two from the Aspergillus family, flavus
The risk of contamination occurs on both ends of the supply chain for many grains, nuts, and cereal crops. Products can become contaminated when mold invades the initial crop supply, or when conditions allow growth in stored foodstuffs. Contamination is difficult to mitigate, and can result in a large loss of product for manufacturers, not to mention health hazards for consumers. And this isn’t an issue confined to wet, warm climates; countries from every continent struggle with these contaminants in their food supply.
These mycotoxins aren’t compounds to sneeze at, either. Zearalenone is known to cause spontaneous abortions in swine, and reproductive malfunctions ranging from birth defects in fetuses to structural malformations in adults. It’s a potent agonist for both the traditional estrogen receptor and the G-protein coupled estrogen receptor, which is the underlying cause for its significant and systemic ability to alter the reproductive system.
Both mycotoxins are carcinogens and hepatogens, as well. They are capable of forming DNA adducts, in which they bind to DNA and prevent its participation in normal cellular functions. This can result in micronuclei formation or polyploidy, when chromosomes segregate irregularly during cell division, which can ultimately result in tumorigenesis. Additionally, both have shown an ability to induce tumorigenesis specifically in the liver, and high amounts in the diet can cause acute liver damage in both humans and animals.
But ecosystems have a way of maintaining balance, and where these two fungi produce particularly nasty toxins, a handful of yeasts have developed a way to metabolize or prevent them. Pichia pastoris and Trichosporon mycotoxinivorans have developed ways that allow them to prevent or degrade aflatoxins and zearalenone, respectively, and research shows that they’re pretty good at it. In trials, spraying trees with Pichia pastoris had a 97% success rate of reducing the amount of A. flavus that was able to grow compared to trees that were not sprayed. Additionally, T. mycotoxinivorans treatment of Zearalenone contaminated solution was 100% effective at degrading the toxin into less harmful metabolites, such as carbon dioxide.
This highlights the importance of studying both pathways within and relationships between organisms, and how, like Pandora’s box, even when things seem out of control, there is still hope (and a solution) if we’re willing to look for it.
Cross posted at https://eeeeesobel.wordpress.com