Mushroom Materials Mania!

This foray into mycology has been eye opening for me. Yes, I've always enjoyed eating mushrooms, but what did I really know about them. What features of a mushroom and funguses make them conducive for making a material? What are the potential applications and at what state of development are they at currently? What would be the benefits of using this type of biomass? Well I suppose to begin answering this let's start from the fundamentals.

Illustration of a fungus's structure with mushroom cap and mycelium - by Jason D'Souza

What is a mushroom and fungus?

Ecological Role: Mushrooms are the fruiting body of a fungus, i.e. how a fungus reproduces. Funguses feed on biological matter using a cornucopia of enzymes and acids to breakdown biological matter into their food. They can feed on dead organic matter, be parasitic, or even live symbiotically. Their association with tree roots is called a mycorrhiza. Tree roots may provide carbohydrates to feed the fungus and the fungus breaks down complex organics into key plant nutrients and increases access to key minerals. They are an essential component of many ecosystems since they help recycle carbon.

Structure and Function:
A fungus is essentially a fibrous network of mycelium. Mycelium is the collective name for individual hyphae, a fiber strand that could be considered analogous to a plant's roots. They spread and form an interpenetrating network through the soil/substrate. When they reproduce they do so via mushrooms; that consist of a stem, a cap, and gills for releasing spores. Not all funguses produce mushrooms. The most common edible mushrooms belong to the order agaricales. (Taxonomy: kingdom (fungi), phylum (Basidiomycota), class (Agaricomycetes), order (agaricales), family, genus, species).   

A typical mushroom from the order agaricales [a]

Mushrooms are still foraged for in the wild, but they are also highly cultivated. As you'll see they are capable of making many interesting products that utilize the proteins in their cell walls or the polysaccharides in their mycelium to build light weight materials. If we are just beginning to study mushrooms for their potential industrial applications, imagine what could be gained from studies on other types of fungal fruiting bodies, what potential might they have as well?

Chemical Composition 

Just like how poison ivy causes a chemical reaction to avoid animal predation, funguses have developed a similar approach to protect themselves from predation. As a result, many species of funguses produce mushrooms that are toxic or could have hallucinogenic effects..... This means that funguses are storehouses of unique compounds, which is why practitioners of folk medicine often utilize mushrooms in their practices.

Why Mushrooms?
1) Funguses tend to grow faster than more complex plants, that means that higher yields are possible within a shorter period of time.[1]
2) In terms of harvesting the mushroom, the mycelium is still left intact so the fungus can still continue growing new mushrooms and have a high productivity. Analogous to picking the fruit of a tree, the fruit is harvested while the tree is left intact to continue growing.
3) Farmers that grow mushrooms in conjunction with other crops can reduce their waste (wood shavings, saw dust, husk, sugarcane bagasse, bananna leaves, stems and straw) while producing a product that supplements their income.[1]

Mushrooms Part II: Why they taste amazing, why they're healthy, and why we need more choices in our grocery stores

Part III will be on current and developing  applications of funguses and mushrooms
Their role in medicine, as colourants, in remediation of soils, and applications in producing faux leather and even making insulation. Stay tuned...

References:

1. Risnen, R. Dyes from Lichens and Mushrooms. In Handbook of Natural Colorants; John Wiley & Sons, Ltd: Chichester, UK, 2009; pp. 183–200.