How To Make Liquid Culture For Mushroom Cultivation. (2024)

In this post, we're going to break down how to make liquid culture, why it's a game-changer for growing mushrooms fast and what a good or contaminated liquid culture looks like (with photos).

Liquid culture, or LC broth, is a blend of water and some basic sugars. It's is used to expand mycelium before you introduce it to grain spawn. There's a variety of recipes out there for liquid culture, and I'll walk you through how to make 3 of them today.

Over my years of dabbling in mushroom cultivation, I've whipped up more batches of liquid culture than I can count. Trust me, even a small misstep like drilling the hole in the wrong spot on the jar lid can lead to losing half your precious culture. So, stick with me as I guide you through the essential do's and don'ts of making liquid culture – because getting it right makes all the difference.

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.

I believe these are the best ingredients since they create a clear culture which can be easily analysed.

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.

OR
Follow the links in the table which contain a more detailed table for each technique.

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

Requirements

• Pressure Cooker (pressure cookers for mushroom cultivation).
• Micro-pore tape/polyfill (here is a discussion on gas exchange lids, however for this tutorial micropore tape will do).
• Liquid Culture Syringe
• Nutrient (Honey, LME, Karo).
• Butane Torch (seriously get one of these it makes flame sterilizing needles very very easy, the needle will glow red in seconds).
• Jars
• Alcohol
• Stirring plate (this will speed up the process).

Create the Liquid Culture Jar.

Grab a 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, if you put it in the centre it will be difficult to tilt and remove all the liquid culture.

Next, fill the jar with 600ml of warm water. Some people like to use distilled water but realistically tap water is perfectly fine and probably adds nutrients.

Measure out the amount of nutrient (24g for me) 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.

Sterilize the Liquid Culture Jar.

Place the liquid culture jar into your pressure cooker and sterilize at 15psi.
It should take around 30-40mins to sterilize the culture and remove all contaminants.
When the time is up, turn off the heat and allow the pressure cooker to cool overnight before moving to the next step.

Inject the Liquid Culture Jar.

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).

Wait 7-14 days.

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.

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.

• 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.

No, Liquid culture does not need gas exchange. The mycelium is submerged in a liquid solution therefore there is no need to for air exchange holes to be placed in your lid.

I am not sure exactly how the mycelium breaths in this situation however it most likely has something to do with absorbing the oxygen which makes up H2O (water).

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.

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.

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).

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.