Guttation

One of the favorite mushroom phenomena; guttation.

You can think of guttation as “mushroom sweat”.

But these little droplets hold a much deeper story than what meets the eye~

Guttation is the expression of (some but not all) metabolic byproducts from mushroom metabolism that can be seen oozing out of the fruiting body.

Fungi are catabolic: catabolism is the sequences of enzyme-catalyzed reactions by which large molecules in living cells are broken down. Part of the chemical energy released during catabolic processes is conserved in the form of energy-rich compounds, such as ATP. Heat is also produced as proteins, polysaccharides, and lipids are degraded. As oxidation continues, carbon dioxide is produced via the Krebs cycle. Hydrogen atoms / electrons from the intermediate compounds formed during this cycle are then transferred via carrier molecules ultimately to oxygen, forming water. Because mushrooms grow so quickly and their metabolism is working so fast, they produce more water than their cells can hold, which they exude from their growing edge.

To put it simply, fungi consume organic matter from their environment and break it down to produce chemical energy and the metabolic byproducts of heat, water and carbon dioxide. Sound familiar? Its the same process we use!

Due to the complexity of these pathways, these guttation droplets often hold dynamic suites of secondary metabolites specific to the fungus that’s producing them. For example, the guttation of Penicillium species can contain penicillin, since it is a secondary metabolite. Many of the compounds that we consider medicinal in mushrooms (beside beta glucans and chitin which come from the cell wall) are in fact, secondary metabolites.

Fomitopsis ohcracea guttation

This is a photo of guttation being exuded from the growing edge of Fomitopsis ochracea, a close relative of Fomitopsis pinicola, or the red belted conk; an incredible medicinal mushroom and one of my personal favorites due to their widespread abundance in the Pacific Northwest. These two species can look almost identical in the felid and the one tried and true way to distinguish is to hold up a lighter to the surface of the fruiting body: F. pinicola melts while F. ohcracea chars.

F. ohcracea doesn’t have nearly as much published research (if any) for its medicinal compounds/actions as it’s red belted counterpart, but I hypothesize they have similar suites of contituents as their all their Fomitopsis cousins, just as Ganoderma species (Reishi complex) have similar suites of constituents across species.

Every time I see this phenomena happening from a medicinal polypore friend: I can’t help but to take my tongue to the droplets and let some slide into my mouth. The guttation is usually bitter, indicating the presence of secondary metabolites. So remember, stop and smell the roses but also stop and take a moment to taste the mushroom sweat!