DNA authentication of wild mushrooms in food products
Mushrooms have been consumed by humans for many thousands of years. While they can be gastronomically valued and nutritionally important, it has long been recognized that only select species of mushrooms are suitable for consumption. Adverse health effects of consuming poisonous mushrooms range from mild illness to death. Many valuable edible mushrooms are unable to be grown commercially, or it is impractical to do so, requiring them to be harvested from the wild. Products containing these wild-collected mushrooms are often sold with the nonspecific and undefined label "wild mushrooms," although in some cases particular species are listed in the ingredients. However, the ambiguity of the definition of "wild mushrooms" in foods makes it impossible to know which species are involved or whether they are truly wild-collected or cultivated varieties. As a consequence, any individual adverse reactions to consuming the mushrooms in these products cannot be traced to the source due to the minimal regula- tions around the harvest and sale of wild mushrooms. For this study, we set out to shed light on what species of fungi are being sold as "wild mushrooms" using DNA metabarcoding to identify fungal contents of various food products acquired from locally sourced grocers and a large online retail site. Twenty-six species of mushroom were identified across 12 food products, ranging from commonly cultivated species to wild species not represented in global DNA databases. One product labeled as "porcini" (a popular wild-collected group of edible mushrooms) was shown to contain potentially toxic species, including an Amanita sp. implicated in causing renal failure. Three of the food products sequenced were found to contain mushroom species that are widely considered as poisonous. This study demonstrates that a large variety of fungi can be sold as "wild mushrooms," even those that are commonly cultivated at industrial scales, and that ingredient labels do not always accurately describe the species included. Of more immediate concern, we demonstrate that poisonous mushrooms are being packaged and sold as food with a large distribution potential.