Mushroom Liquid Culture

What is Mushroom Liquid Culture?

Liquid Culture is a sterile mixture of water and one of a few specific sugars. (we will tell you how to make liquid culture below). The purpose of this nutritious mixture is to develop mycelium growth, once it has been inoculated with mushroom spores.

You could think of liquid culture as mycelium floating in a nutrient broth. Liquid culture makes inoculating substrates easier. Once the mycelium has established itself in the nutritious, sugary broth, the mycelium-rich mixture can be inoculated onto a substrate of your choice or stored as a living mushroom culture.

What are the advantages of using Mushroom Liquid Culture?

• The risk of contamination is lower
• According to Liquid Culture Shroomery, using liquid culture reduces incubation time
• Limitless mycelium growth – once mycelium starts developing, it doesn’t stop

What are the disadvantages of using Mushroom Liquid Culture?

• A sterile working environment is essential
• Better suited for advanced mushroom cultivation
• You can’t see contamination in liquid culture. You will only know your mixture is contaminated when you use it.

What you will need:

• Grain spawn jar, also known as an airport jar
• Pressure cooker
• 10ml syringes
• Needles (Note: the bigger the number, the smaller the needle. We recommend 18 gauge)
• One of the following sugars, to mix with water: organic honey, corn syrup, corn sugar, light malt extract, dextrose (glucose).

Sucrose (household sugar) should not be used. For this guide, we chose honey.

What is the best sugar to water ratio?
A ratio of 4% is best.
This equates to 4cc, 4ml, or 1 teaspoon of honey per 100ml of water.
A 3% to  5% ratio is fine, but be aware, too much sugar (10% and more) is harmful to mycelium.

A step-by-step guide to making your own mushroom liquid culture:

1. Carefully measure and mix the sugar you choose with water in the jar. Warm water will help the sugar dissolve quickly, but it is optional.
2. Put the lid on the jar.
3. Cover the top of the jar with aluminum foil and put it in a pressure cooker.
4. Cook at 15 psi for no longer than 15-20 minutes. Over-cooking the sugar will lead to caramelization, which will result in poor to no mycelium growth.
5. Allow the pressure cooker to cool off naturally before removing the jar. Be careful. The jar will be very hot.
6. Allow the jar and contents to reach room temperature.
7. Add some mother culture to your liquid culture. (more on where you can buy your mother culture below).

Important Note:
If you are not using an airport jar, don’t remove the lid until you are ready to inoculate your substrate and replace the lid as soon as you are done.  This will prevent airborne contaminants from entering the jar and ruining your mycelium.

How to add mother culture to your liquid culture

Once your jars have cooled after being in the pressure cooker, you can add a few ccs of mother culture. Shake the mother culture briskly to break up the mycelium.

If you are using a syringe needle for the first time, it should be sterile. If not, use a lighter or candle to sterilize the needle by holding it in the flame until it is red hot. Careful now! Use an alcohol wipe to cool the needle down.

Insert the needle through the self-healing injection hole in your airport jar lid and inject 1 to 2ml of liquid culture into the jar. Repeat if you have more than one jar.

What to do with a jar of mushroom liquid culture

Simply leave it on the shelf and wait for it to grow. Most mushroom cultures grow best at around 77°F (25 °C). Any variation in this temperature will cause them to grow more slowly.

Do not disturb the jars for 4 to 5 days. During this time, the mycelium enters its growth stage, and you will see it grow as it consumes the sugar. After the initial resting period, you should swirl the culture every couple of days to break up the mycelium and introduce oxygen into the culture.

When the mycelium has grown and almost fills the jar, vigorously agitate the liquid culture to break the mycelium up as much as possible. When you are ready to inoculate your substrate, transfer the culture to agar, or share some with your friends, tilt the jar so that the liquid reaches the injection port and, with a sterile syringe and needle, suck the culture into the syringe until it’s full.