The Mushroom Lifecycle
The fungal kingdom is divided into several sub groups, or phyla, each with its own unique lifecycle and characteristics. One of these groups, known as the basidiomycetes, includes all of the species one is likely to try cultivating (e.g. Oysters, Shiitake, Reishi). It is recommended that you come to understand the saprophytic (decomposing) basidiomycete lifecycle before beginning your hand at cultivation or remediation. This will certainly help you to not only understand what aspects of nature you are trying to mimic throughout your cultivation trials but will also (hopefully) result in greater successes and lower rates of contamination from competitor molds and bacteria that are trying to eat the mushroom’s food you are providing.
We begin with the spore. Spores prolifically develop on a microscopic layer of fertile (spore-producing) tissue known as the hymenium, This tissue develops in mature mushrooms on the surface of structures called gills, teeth, or pores, which themselves are often found underneath the cap of a mushroom. A given mature mushroom can produces millions, or even billions, of spores in a single day, all of which are ejected from the mushroom at an incredibly high force to enter their surrounding environment. When a given spore lands in a suitable habitat, it quickly germinates, producing a single-cell filament, or hypha (plural hyphae), which begins to grow through its substrate, or food source, in search of a genetic mate. Like the sperm and egg of animals, spores contain only half the genetic information of their parent and thus need to join with the hypha of another spore in order to be genetically whole.
Once the spore does encounter a mate, the two hyphae fuse into a joined network, which is then referred to as mycelium. This mycelium now has all the genetic information it needs to successfully grow through its environment and ultimately produce mushrooms. As the mycelium grows through its substrate, this thread-like structure continuously branches in all directions, forming an incredibly dense network (imagine a web with clearances smaller than any woven structure humans can produce) in the search for water and food. In the case of the decomposing fungi, as the mycelial tips encounter organic matter they exude a mixture of complex enzymes upon this material in order to convert this complex matter into forms the fungus can use as food. The main energy source for these fungi is the long chain-like molecule of cellulose (the fibrous stuff that makes up the walls of plant cells). Saprotrophs have developed an array of enzymes that can readily snip this long chain in to simpler, shorter carbohydrates that the fungus can then absorb and metabolize. Some saprophytes have even adapted to break down lignin, the highly complex compound that makes wood hard and rigid, something few things on Earth are able to accomplish. As the fungus is producing these degrading enzymes it is also releasing various metabolites to protect itself from surrounding competitors in the environment. Being only one cell thick, the mycelium has no outer barrier to infection and thus has evolved to defend itself from harmful bacteria and fungi in its substrate through the use of its own anti-biotic and anti-fungal compounds. These are some of the compounds that fungi produce that are medicinally beneficial to humans, as our bodies use them in a similar manner.
If the fungus runs out of resources or a change in environmental conditions arise (e.g. a temperature drop & increase in humidity), the mycelium will be triggered to produce a mushroom (that is, to “fruit”) and will start to accumulate in to numerous tiny pinheads, or primordia. These primordia will soon develop into a mature fruiting bodies (what we commonly refer to as the mushroom) after a few days, at which point they will begin to drop millions of spores and continue the lifecycle anew.