Written By Cole Johnson, DNA Scientist
Many fungal species, such as the yeast Saccharomyces cerevisiae, are widely important for their role in activities such as baking or brewing. Other foods such as soy sauce and cheese contain fungi themselves. Some, like mushrooms and truffles, are sources of food on their own. Among the estimated 1.5 million species of fungi that inhabit earth, about 300 are known to cause illnesses ranging from allergic reactions all the way to life-threatening infections. While this number may seem small, these species of fungus are still able to cause damage and even death in some cases.
An important term to note is IFI, or Invasive Fungal Infections. These infections are the ones that can cause increased disease and mortality. Immunocompromised people have the highest chance of being infected by a fungal-borne food pathogen. Routine testing of manufacturing equipment is important to make sure that there is no opportunity for these infections to occur. Most occurrences of fungal food borne pathogens start from either dairy products or dietary supplements. Nearly all invasive yeast infections that have been linked to food have been connected to dairy products, especially yogurt. Among the yogurt industry, there was a case of a contaminant in Mucor circinelloides which caused over 200 people to have vomiting, diarrhea, and nausea. The manufacturer of the yogurt withdrew all the products once the infection was revealed, but more frequent quality testing could have helped to prevent it.
These pathogens can synthesize secondary metabolites that can be harmful to humans in some cases. The most reported food-borne fungus is Aspergillus flavus. It exists as one of the dominant species found in common stored products, especially grains. It thrives in these conditions as the low water activity and high-temperature environments supply the optimal conditions for growth. This fungus possesses the ability to produce the B aflatoxins, which especially occur in cheeses. This toxin is a carcinogen that can cause cancer and other illnesses in some cases. The true extent of these pathogens is not known, and more research is needed to know their full impact on public health.
Fungal-borne food pathogens may not be as common as bacteria, but it is still important to recognize how they occur and how they can be prevented. By incorporating quality testing into their manufacturing process, companies can work to make sure their products are safe from any fungal pathogens.
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