Grow mushrooms the EZ way.

How To Make Liquid Culture For Mushroom Cultivation.

Injecting a liquid culture jar for mushrooms

Liquid culture (also known as liquid broth culture or LC) is a sterilized nutritious solution which can be used as a media to grow, store and swap mycelium tissue while growing mushrooms. 

There are several liquid culture recipes to choose from which I will discuss in this guide.

Learning how to make liquid culture is a great skill for people wanting to grow mushrooms for mycology.

It is often the stepping stone for beginner growers who don’t have the sterile technique to perform agar work.

Mushroom growers can create unlimited liquid culture spawn from one LC syringe and use it to inoculate grain jars, and, because liquid culture lasts for months it is perfect for home growers.

By the end of this post you should know how to make at least 3 liquid culture recipes for growing mushrooms and understand what bad liquid culture looks like.

How To Make Liquid Culture?

Liquid Culture Broth is created by adding a nutritious medium into water and sterilising the mix.

For mushroom growing the culture is often enriched with sugars to feed the growing mycelium. 

I have created a table below which covers the most common liquid culture recipes, choose a mixture you wish to use then follow the instructions in this post. 

Recipe Name Nutrient Amount (Grams) Water Percentage (NA:W)
Karo LC 24g 600ml 4%
Honey LC 24g 600ml 4%
LME LC 1g 600ml 0.16667%

 

If you want to create a formula which is not listed in this table then you simply do the following:

(Water X Percentage) / 100 = Nutrient Amount.

OR

(Nutrient Amount / Percentage) X 100 = Water.

Step By Step Guide To Create Liquid Culture

These techniques discussed require you to have and use a pressure cooker, if you don't have one checkout my post about the best pressure cooker for growing mushrooms at home.

We recommend creating multiple jars at one time to improve the chances of creating a clean liquid culture broth.

Requirements

Step 1 – Create Mixture.

Find a glass jar and put a hole in the lid using a screwdriver or something similar.

The hole should be as close to the edge of the lids as possible as show in this picture below.

Small hole in edge of lid for liquid culture

Next, fill the jar with with 600ml of warm water. It is better to use distilled water but realistically tap water will also work fine.

Measure out the amount the amount of nutrient you are going to be using and add it to the jar then give it a quick swirl/mix with a spoon.

Place 2 strips of micropore tape over the hole you created in the lid and screw on the lid to the jar.

Finally, place some foil over the top of the jar and secure it with a rubber.

Jar held in hand with foil over top

Step 2 – Sterilize Jars.

Place the liquid culture jar into your pressure cooker and heat until the pressure reaches 15psi.

Once 15psi is reached leave for 30-40mins to sterilize the culture.

When the time is up, turn off the heat and allow the pressure cooker to cool overnight before moving to the next step.

15psi Sterilizing mushrooms

Step 3 – Inoculate Liquid Culture Mixture

The first thing you want to do is find somewhere to inoculate your mixture. It is possible to do this on a kitchen counter if it is clean however using a still air box is always advised.

  • Collect your butane lighter, liquid culture syringe and micro-pore tape.
  • Wipe down your surfaces and put on gloves and a face mask.
  • Remove the jars from the pressure cooker.
  • Wipe the lid of the jar with alcohol wipes.
  • Pop a piece fo micro-pore tape on top of the jar which you are going to fold down.
  • Shake the needle to spread out the current mycelium.
  • Flame sterilize the needle until it is glowing red.
  • Insert syringe and inject 1cc of liquid culture.
  • Remove the syringe and flip down the micropore tape.
  • Place the jar into incubation temperatures(18-20c or 64-68f).

Step 4 – Wait.

  • Stir the jar daily to prevent clumpy solid mycelium masses (without opening the jar).

Note: Alternatively you can place your jar onto a stirring plate to speed up the process.

Lme liquid culture complete

How To Use Liquid Culture?

  • Sterilize a syringe by filling it, then emptying it with boiling water 3-4 times.
  • Wipe the liquid culture jar lid with Alcohol Wipes.
  • Flame sterilize the needle until glowing red then insert into hole in the lid of the jar.
  • Pull back on the syringe until you have collected some mycelium.
  • While removing the syringe, cover the hole with micropore tape just as the syringe leaves the jar (has to be fast).

Note: If the mycelium clumps are too big for the syringe then pump the syringe inside the jar a number of times to break up the mycelium into small pieces.

What Does Good/Bad Liquid Culture Look Like?

Good Culture

The liquid should be clear and you should be able to see through to the other side of the jar. Inside the liquid, there should be a white clump of mycelium or lots of little clumps.

Bad Culture

Common signs of contamination are if the culture is cloudy and you cannot see through it  (wait a week after inoculation to check this as sometimes the mycelium cleans up the culture), if it releases a foul smell or has a green colour scum on the top of the culture when it is left to settle for a few days.

Normally the best way to find out if the culture is clean is to try it out on grain or agar and see if it contaminates. If you follow sterile technique but the jars are repeatedly being contaminated in the same way it’s likely your jar of liquid culture. 

Why Make Liquid Culture?

  • Faster Growth – Since the medium already contains live mycelium it normally colonises a substrate substantially faster. This gives LC an advantage over spores.
  • Unlimited Mycelium Supply – if you learn how to make liquid culture you can turn 1 LC syringe into an unlimited supply. However, you must take senescence into consideration (so use a master jar).
  • It’s Cheap – making liquid cultures is very cheap and can be done with household ingredients.

Does Making A Liquid Culture Require A Pressure Cooker?

Actually, no, you can sterilize the  liquid culture recipe in a microwave if you don’t have a pressure cooker.

Place your mixture into a microwavable container, the put it inside the microwave for 3 minutes, remove and shake, then place it in for another 3 minutes.

How Long Does Liquid Culture Last?

Liquid Culture can survive at room temperature for 6 months until the nutrients in the solution have been used up.

So you're Liquid culture is good for a decent amount of time suspended in the solution

If you need to your liquid culture to last longer putting it into a refrigerator should allow it to survive for years. 

When to Stir/Shake Liquid Culture?

It is recommended to shake or stir (using a magnetic stirrer like this) at least once a day. 

If you don't do this the mycelium will create a huge blobby mass as seen below. 

This also speeds up the expanding process as there is more surface area for the mycelium to grow off.

I did not shake those Jars so I could highlight what a clean culture would look like (clear).

How Long Does Colonization Take?

Liquid culture usually takes between 7-14 days to accumulate enough mass to be used in an actual inoculation.

It can take longer for the Jar to be completely colonized and the growth to slow down.

Several factors can come into play here such as whether you shake the culture, temperature and Mycelium vigour.

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