How To Make A Mushroom Liquid Culture

This guide will show you how to make your very own mushroom liquid cultures. You will then be able to expand out mycelium of your chosen mushroom to further your mycology endeavors.

This is what we are going to be making:

What is a mushroom liquid culture?

A liquid culture is a type of mushroom culture that is grown in a liquid medium instead of on solid agar plates. It is commonly used in the cultivation of mushrooms and other fungi for commercial, research, or hobby purposes.

In a liquid culture, mushroom spores or mycelium are added to a nutrient-rich liquid medium such as malt extract or potato dextrose broth. You then incubate under controlled conditions (for example temperature, light, and humidity). The mycelium grows and spreads throughout the liquid. You can then use your culture to inoculate substrates to grow more mushrooms.

Why use a mushroom liquid culture?

One of the advantages of using a liquid culture is that it can easily be scaled up or down depending on the size of the production. Liquid cultures also allow for efficient use of space as the liquid can be stored in jars and takes up less room than innoculated substrate.

Liquid cultures are commonly used in the production of gourmet and medicinal mushrooms, such as shiitake, oyster, and reishi, as well as in the research of fungal biology and genetics. They are also popular among hobbyists who want to grow their own mushrooms at home.

We stock a large range of gourmet and medicinal liquid cultures. These can be used for innoculation or expanded further using this guide.

What materials do I need to make a liquid culture?

To create a liquid culture, you will need:

A nutrient-rich liquid medium (Sterilized water with a nutrient added – more on this below!)
A sterile mason jar with a lid that has a hole in the top.
Micropore tape
Mushroom spores or mycelium
A sterile syringe or inoculation loop
A magnetic stirrer (optional) A magnetic stirrer can be a helpful tool when making liquid culture for mushroom cultivation. The stirrer helps to distribute the spores or mycelium evenly throughout the liquid medium and can also promote faster growth of the mycelium.
A sterile scalpel (only neccessary if using agar or a spore print)

A simple way of making a breathable lid for your mason jar

Take your mason jar lid and drill a hole in the middle of it. This should be about 6mm across. You can then cover this hole with 2 layers of micropore tape which acts as a filter and breathable hole for your mycelium. There are more sophisticated ways of doing this but the aforementioned is quick, easy, cheap and works!

What can I use to inoculate my liquid medium?

To inoculate a liquid medium for mushroom liquid culture, you can use various sources of mushroom mycelium:

Spores: Spores are a common choice for inoculation. They can be obtained from a mature mushroom’s spore print and introduced directly into the liquid medium using a sterile scalpel.
Mycelium: You can obtain mycelium from a culture grown on agar or a solid substrate. A small piece of this mycelium can then be transferred into the liquid medium using a sterile technique.
Liquid Culture Syringe: If you already have a mushroom liquid culture, you can use a small amount of the liquid culture (containing mycelium) and transfer it into the nutrient-rich liquid medium using a sterile syringe.
Liquid Culture Slurry: You can create a slurry by blending mycelium with sterilised water. This slurry, containing mycelial fragments, can then be added to the fresh liquid medium

How to make a nutrient-rich liquid medium for your culture

I want to preface this guide on making a nutrient-rich liquid medium by giving the most straight forward solution (no pun intended). Put 2-4 grams of sugar such as honey or karo per 100ml of distilled water and sterilise. If you want to get fancier – read on!

Ingredients:

Light Malt Extract (LME) or Malt Extract Agar (MEA): Provides carbohydrates and nutrients.
Sugar: A simple sugar for energy.
Yeast Extract: Contains vitamins, minerals, and amino acids (optional)
Peptone: A source of nitrogen and amino acids (optional)
Water: Distilled or sterilized water to prevent contamination.

Steps:

Prepare Your Ingredients: Measure the components based on a recipe or a predetermined ratio. Typical ratios might include 2g LME, 1g dextrose, 0.1g yeast extract, and 0.1g peptone per 100ml of water.
Mix Ingredients: Add the measured amounts of LME, dextrose, yeast extract, and peptone to the distilled water. Stir thoroughly to dissolve the components completely.
Magnetic Stirrer: Add the magnetic stirrer if using.
Sterilize: Once dissolved, sterilize the liquid medium by autoclaving or pressure cooking at 15 psi (123°C) for around 15 minutes. The longer you sterilise over 15 minutes the higher the chance that your sugars will caramelise rendering your medium useless for mycelium cultivation.
Cooling and Storage: After sterilization, let the liquid medium cool down to room temperature in a sterile environment, such as a laminar flow hood or a SAB. Once cooled (takes around 4 hours), it’s ready to use for inoculation.

Inoculation

6. Inoculation: To inoculate use aseptic techniques to infuse the liquid medium with the desired mushroom culture. This can be done by transferring a small piece of mycelium or spores into the liquid medium using a sterile syringe or other sterile tools as previously discussed.

7. Incubation: Seal the jar (using your breathable lid) with the inoculated liquid medium and place in a warm, dark place suitable for your specific mushroom strain. Monitor for signs of growth (such as mycelium spreading through the liquid) over the coming days or weeks.

8. Mycelium Distribution: If you have used a magnetic stirrer you can simply put your jar on the stirrer plate and give it a whizz for a few seconds – minutes. Ideally this should be done once a day until the culture is ready. Otherwise you will have to manually swirl the culture being careful not to get your lid wet (you don’t want the solution to touch your breathable filter).

And there you have it!

What do I do with my mushroom liquid culture once it is ready?

Once your mushroom liquid culture is ready (usually takes about 2 weeks), you can use it in various ways depending on your intended purpose. Examples are inoculating new substrates, expanding your culture, or conducting experiments. Here’s a general guide on how to use mushroom liquid culture:

Inoculating Substrates:

Prepare Substrate: Start by having your chosen and suitable substrate ready.
Sterilize Equipment: Ensure all equipment and surfaces are clean and sterilized before starting the inoculation process.
Inoculation Process: Use a sterile syringe to withdraw the liquid culture. Now you can inject the liquid culture into your prepared substrate. The amount needed depends on the volume of the substrate and the concentration of the liquid culture.
Incubation: Once inoculated, place the substrate in a suitable environment (correct temperature, humidity, and darkness) for the specific mushroom species to allow mycelium growth. You can periodically monitor for signs of colonization without any contamination.

Transferring to New Medium:

Prepare Fresh Medium: If you want to expand your liquid culture, prepare a fresh batch of nutrient-rich liquid medium.
Inoculate New Medium: Use aseptic techniques to transfer a portion of the existing liquid culture into the fresh medium. This process can be repeated to increase the volume of your liquid culture.
Incubation: Allow the new medium to incubate until the mycelium grows and spreads throughout the liquid culture.

Maintenance and Storage:

Regular Checks: Periodically check your liquid culture for signs of contamination or unusual growth.
Storage: Store any unused liquid culture in a refrigerated environment to prolong its viability. Make sure to follow proper storage procedures to maintain the culture’s health.

Remember, maintaining sterile conditions throughout these processes is crucial to prevent contamination and ensure successful growth of your mushroom cultures. Working in a clean environment and sterilizing equipment are key to successfully cultivating mushroom liquid cultures.

How to tell if my mushroom liquid culture is contaminated

This subject warrants an article all of it’s own so that’s exactly what we have done! Have a read of “how to tell if my mushroom liquid culture has gone bad“.