Signs of Spring 10: Fungi

Fungal mycelia. Photo by R, Hile. Wikimedia Commons

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In order to really appreciate fungi we need to understand at least an overview of their general structure. Most fungi are complex, multicellular organisms that grow in thread-like strands called “mycelia.” The mycelia interweave themselves around the fungus’ habitat components and secrete digestive enzymes and absorb digested food products and other nutrients. Fungi can be quite large (the largest organism on Earth, in fact, is a soil dwelling, honey fungus (Armillaria solidipes) in Oregon that has spread out over an area of 3.7 square miles and weighs an estimated 605 tons! It is also may be over eight thousand years old!).

Fungi inhabit many different types of habitats. Some (like the honey mushroom) live in soil while others live in close associations with other complex organisms. Plants often have specific fungi associated with their roots. These fungi are called “mycorrhizae” and for many plants they are absolutely essential for the plant roots to work properly and for the plant to survive and grow! Other types of fungi can be found in and on plant leaves and inner tissues. These fungi may be important symbionts in the plant’s metabolism, or they may be potential pathogens or decomposing agents when the plant dies or begins to senesce. Fungi can also be found on and in animals (including humans) and are a part of the animal’s microbiome. Fungal microbiome cells are much less numerous than bacterial microbiome cells, but recent research suggests that they may have very specific and very significant physiological functions.

Morel mushroom. Photo by M. Smiley, Wikimedia Commons

Fungi were once classified with the plants, but a more modern approach puts them in a group (or set of groups!) all by themselves. This large group classification can then be broken down using a variety of features and characteristics including mechanisms of reproduction. Some fungal groups make spore producing, reproductive structures called mushrooms. For many people, these mushrooms (which quite literally are the tiniest tip of the fungal “iceberg!”) are the only visible and only recognizable parts of all of the fungi that surround them!

Fungi are extremely old and extremely complex organisms. They synthesize a wide variety of primary and secondary chemicals that have enabled them to survive and thrive in their environments and in their symbiotic relationships. The robustness of fungal chemistry has led some researchers to refer to them as “pharmaceutical factories” that may be sources of untold types of new drugs that could contribute to human health.

A research group at Penn State just published an article describing the concentration of two anti-oxidant chemicals (ergothioneine and glutathione) in thirteen species of edible mushrooms (Food Chemistry, October 15, 2017) . These anti-oxidants may, if they can survive the digestive processes and be absorbed into the blood stream intact, help the body to control damaging free radical chemcials that are generated in every cell of the body as a consequence of energy metabolism.

Free radicals have been implicated as causative or contributory agents in variety of neurodegenerative disorders (like Parkinson’s and Alzheimer’s diseases), in many types of cancer and in the overall process of aging. In a recent Penn State Newswire story related to the Food Chemistry article, Dr. Robert Beelman  (professor emeritus of food science, Penn State University) pointed out that in countries where these anti-oxidant rich mushrooms are traditionally consumed (like France and Italy) there is a lower incidence  of both Parkinson’s and Alzheimer’s diseases than in the United States (where these mushrooms are not traditionally eaten).

Boletus edulis. Photo by Dezidor, Wikimedia Commons

Not all mushrooms have the same levels of anti-oxidants, but all mushrooms tested did have significant levels of them. Further, the concentrations of ergothioneine and glutathione are correlated with each other (mushrooms with high concentrations of one also have high concentrations of the other), and cooking does not affect the molecular structure or anti-oxidant properties of either chemical. Wild porcini mushrooms (Boletus edulis), by the way, had the highest levels of anti-oxidants in this study.

Another glimpse into the chemical potential of mushrooms comes from a 20012 review article in 3Biotech by S. Patel and A. Goyal. Twenty genera of mushrooms and the chemicals that they produce are discussed in this article. Many of these chemicals (which range from polysaccharides, to proteins, to fats) have already shown to be efficacious in treating conditions like diabetes, allergies, high blood cholesterol, kidney diseases, and disorders of the immune system. Some of these chemicals also had novel anti-bacterial (i.e. “antibiotic”) and anti-oxidant properties! Some of these chemicals also via their impacts on steps in cell replication may have use as chemotherapy agents in the treatment of cancers.

The authors encourage more intense evaluation and exploration of wild and exotic mushroom species for their possible novel chemical constituents. They also note the long history of the use of mushrooms in traditional medical practices from a wide variety of cultures.

Which then gets us to wild mushrooms.

Over the years I have had a number of friends who hunted and harvested wild mushrooms. Many of the mushrooms collected in the wild cannot be grown in mushroom farms because they are generated by mycorrhizal fungi or grow out of recently deceased trees! I have always hesitated, though, to join in the hunt for two divergent reasons: 1. The fear of making a mistake and picking and gobbling down some poisonous mushroom variety, and 2. An ecological concern that removing the mushrooms (and all of their reproductive spores) from an ecosystem would seriously impact the local viability of the species.

Now, Reason #1 can be minimized by only harvesting extremely recognizable types of mushrooms and by going out with someone who is experienced with mushrooms. Reason #2, though, is a very compelling brake on wild mushroom harvesting (so mushroom people, leave some ‘shrooms behind!).

There are four species of mushroom that I would feel comfortable picking and eating:

1. 

   Puffball. Photo by Grindlemutter, Wikimedia Commons

   Puffballs: puffballs look like their name, rounded, globe-like sometimes extremely large. You find them usually in late summer or fall in open woods or pastures (they are soil dwelling fungi). The only thing that might look like a puffball is an early stage “death cup” mushroom (clear enough name for you?), but if you cut into the puffball the inside with be a homogenous white (you will see the forming stalked mushroom inside the death cup).

2. Morels (pictured above): I have written about morels before (see Signs of Summer 2, 2015)). They are extremely popular, high quality mushrooms that look like little pine cone trees or cylindrical brains. They are very distinctive looking. They can be found in April or May usually near old elm trees (they are mycorrhizae fungal associated especially with elm roots). They are also hollow inside and this feature can be used to make absolutely sure that you have a morel.
   

   Chanterelle. Photo by User.Strobilomyces, Wikimedia Commons

   3. Chanterelles: chanterelles are yellow to orange, trumpet-shaped mushrooms that grow singly or in clumps. They are found in summer and in fall and are associated with many types of trees (both a variety of hardwoods and conifers). They are, like the morels, mycorrhizal on the tree roots but are not nearly as selective about their trees as morels.

   4. Chicken of the woods: chicken of the woods mushrooms are also yellow to orange and, like the chanterelles, very brightly colored. Chicken of the woods grows on dying to

   

   Chicken of the woods. Photo by Gargoyle888, Wikimedia Commons

   dead trees (especially oaks). This fungus is breaking down the old tree’s organic materials and, via its mushroom, sending out its spores on to find anew home to linger in.

This past summer I was given two bags of freshly collected chanterelles by a generous friend. I found a really great recipe for preparing them and enjoyed them very much. I also spotted,while on a bike ride, a fallen oak tree covered with chicken of the woods mushrooms but let that one go its natural course. It is hard to pick and choose when the mushrooms are so delicious!