Utilizing a nutrient-rich liquid medium allows growers to avoid contamination that could harm the culture. To start, you will require a sterile workspace; wipe down surfaces and tools with alcohol cleaning solutions before working under a laminar flow hood, if applicable.
Make a mason jar or media bottle ready by sterilizing it in a pressure cooker, adding a magnetic stir bar sterilised in boiling water and a 10ml syringe equipped with 16 or 18 gauge needle.
Ingredients
Liquid cultures for mushrooms consist of living mycelium suspended in lightly nutritious water. A standard recipe involves 500 milliliters of filtered, non-chlorinated water combined with 10 grams of honey or light malt extract for rapid mycelial growth. This affordable mix offers rapid mycelial expansion.
This basic recipe can be modified for specific mushroom species to maximize colonization rates, with sugars such as brown cane sugar being substituted and additives such as peptone or yeast added as necessary to promote optimal growth. Experimentation is key in developing an effective liquid culture recipe as different sugar ratios have different impacts on mycelium formation.
To create a liquid culture, start by sterilizing its containers – this should preferably be done with a pressure cooker following manufacturer guidelines. Mason jars are often preferred due to being inexpensive and readily available – plus featuring two-piece screw-on lids safe for pressure cooker use. For added convenience consider investing in “airport lids,” which have self-healing injection ports as well as filters to facilitate air/gas exchange.
Storage
For optimal spore production and inoculation of spawn, it is critical that liquid cultures remain at room temperature. Furthermore, daily stirring (using either magnetic stirrers or spoons) of each jar or shaker should take place to prevent mycelium clumping together and becoming too thick.
As part of your liquid culture recipe, it is also recommended to create a clean working environment by wiping down tools and surfaces before each procedure. A laminar flow hood can help sterilize jars of liquid culture more efficiently; additionally, labels should contain essential information, including creation date and strain data to avoid confusion or mix-ups between batches of culture created at different times.
Preparation
Liquid culture (LC) is a fast-growing medium that allows spores or mycelium to quickly expand in volume. LC also cuts incubation times down, requires less space than agar and doesn’t suffer the same contamination issues that agar does when contamination happens.
Assuring the cleanliness and sterilization of jars and lids is of utmost importance for successful mycelial culture. A magnetic stir plate or glass marble can be placed at the center of each jar to agitate mycelium evenly across its entirety.
Dextrose or malt extract solutions tend to work best as these sugars are easily metabolized by mycelium for fast and healthy growth. Honey can sometimes be used, though its caramelization during sterilization could prevent its clear application as a solution.
Working in a clean and closed environment is of utmost importance, such as using a laminar flow hood. Be sure to clean all tools and surfaces using 70% isopropyl alcohol to disinfect them thoroughly, keeping an eye out for changes in color or clumping that could indicate potential contamination with competing organisms.
Testing
Mastering liquid culture can be a rewarding journey for mushroom cultivators. This approach allows growers to scale up operations while increasing yields and decreasing colonization times.
Mycelial cultivation can be challenging and requires an extremely clean working environment and exact techniques; even the slightest mistake can kill or stunt mycelia growth.
For maximum effectiveness, use a light malt extract (LME) recipe of 1g LME per 600ml water. Other sugars such as honey may also be included but may interfere with mycelium growth.
Before using a jar of liquid culture (LC), make sure it and any tools intended to use with it have been sterilized in an sterile environment or laminar flow hood. Any cloudiness, color changes or unpleasant odors in the LC are signs of contamination that should not be used – however this process may take several attempts before your final result can be used to inject into agar plates or create grain spawn.