Isolating Cultures

By Melanie Andromidas
colkage with culture plates, grain spawn and mushrooms

One of the components that play into the complexity of mushrooms is the fact that each spore print, has the capability to grow millions of individual cultures. When grown out on agar, however, sectoring out that many would be a bit of a hassle. Usually, you’ll be able to isolate up to five individual cultures. These cultures can then be grown out on their own plates, put in grain, and ultimately fruited to see which phenotypes, or physical characteristics, they possess. 

Why Would You Isolate a Culture?

There are faster ways to grow high-quality mushrooms, so why would you bother with isolating cultures? Well, take the Elm-Z, bred by Ja Schindler of Fungi for the People, as an example. It’s a spore isolate of Elm-A. In almost all ways they’re exactly the same, but Elm-A thrives in colder temperatures and Elm-Z does well in warmer times. This slight change enables mushroom farmers to grow Elm Oyster mushrooms year-round by rotating between the two. 

Say your favorite mushroom tastes fantastic, but you think it would be higher quality if it had a different texture. Running trials until you find one that has the texture you desire would give you a souped-up version of your favorite. Texture is one of many traits that isolating helps to develop or refine, providing endless possibilities. 

How Do You Isolate Cultures?

Spore streaks starting to grow

The process of sectoring cultures takes time, especially if you’re doing a big stack of dishes all at once, but it’s really not complicated. To start, you need to collect a spore print from your mushroom by placing it gill or pore side down on a piece of clean paper, glass, or aluminum foil, covering it, and leaving it overnight.

Once collected, the spores are caught with an inoculation loop which is used to create streaks across the agar plate, taking care to space them out to help make the sectoring process easier. They’ll then need time to grow enough to see the individual cultures. As they grow, the cultures will develop different looks and grow out mostly from the streaks, so isolating them shouldn’t be too difficult. 

Each new culture will need its own fresh agar plate. Slice a line down the middle of the clean plate with a flame sterilized scalpel to cool it. Cut a small chunk of the culture you’re isolating out and place it mycelium side down along the slit in the agar. Close and seal with parafilm, then repeat until all the cultures are isolated, making sure to sterilize the scalpel between each use. 

To see which phenotypes the cultures possess, they’ll need to be fully grown out all the way from agar dish to fruiting block. Once the mushrooms have fruited, it’ll be time to decide if the phenotypes that developed are ones worth continuing to grow. 

How will Isolating Cultures Change the Future of Mushroom Farming?

Black Pearl Oyster Mushroom
The Black Pearl exploded onto the mushroom scene and became a swift favorite of many.

With the complexity of mushrooms, the mushroom farming world is ever-changing. New strains pop into the market and swiftly gain in popularity. Currently, the Black Pearl King is one such new strain that is dominating the mushroom scene. 

Keep in mind, however, that not all isolated cultures turn out well. Even the ones that do often won’t be where you want them the first try. Find the one closest to what you’re wanting and keep it. Don’t be surprised if it takes several generations to get your desired results. If several of your experiments grow out all the least desirable phenotypes and are therefore unusable, don’t get discouraged. Experimenting with isolating cultures may just lead you to discover the next highly desired strain. 

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