Most mushrooms produce spores. When a mushroom spore germinates, the mycelium that emerges from the spore generally has one nucleus per cell, and we refer to this as hyphae, or monkaryotic mycelium. When hyphae that emerged from two individual spores of the same species cross paths, if they’re compatible, they join together to exchange DNA between them. The resulting mycelium generally has two or more nuclei per cell, and is referred to as dikaryotic mycelium. This mycelium, formed from two separate hyphae, is the very definition of a strain.
Since it only takes two spores to make a strain, you can easily see how many strains can potentially differentiate when you use an inoculating loop to swipe thousands of spores from a sporeprint onto a Petri dish of agar media. The process of strain isolation involves transferring these individual growths, or sectors away from each other, so that each can be expanded and fruited to determine the best performing strains. Strains with the desired characteristics will then become part of your permanent collection, stored long-term in test tubes as master culture slants.
The full release of our DVD “Let’s Grow Mushrooms!” demonstrates this process visually, showing you the Petri dish cultures before and after the transfers.
Enjoy the clip. Remember, this is only a sample clip pieced together from several sections of this chapter.
Marc R Keith