Liquid culture solutions containing adequate amounts of nutrients provide young mycelium with the tools it needs to adapt and be resilient during its spawn run.
Thorough sterilization of liquid culture recipes is of utmost importance when working in an open or enclosed environment (like a laminar flow hood) so as to minimize airborne contaminants.
Ingredients
Growers often experiment with various liquid culture recipes until they find one that suits them, playing around with ingredients until finding one they find satisfactory. However, too many extra ingredients could cloud the solution and mask contamination risks.
Liquid culture recipes typically consist of distilled water mixed with light malt extract or honey as the added nutrient, then inoculated with spores before placing the culture in a suitable jar (ideally an airport (also called grain spawn) jar that provides access for inserting syringes without risk of airborne contaminants).
Once a jar has been sterilized, it must be stirred regularly to introduce oxygen and break apart any clumps of mycelium to ensure even colonization. Many growers opt for using a magnetic stirrer while some growers even opt for simply stirring with a glass marble before sterilization for similar effect.
Sterilization
Liquid culture is well known for quickly colonising substrates and needing less upkeep than spores; it also requires less maintenance. Unfortunately, liquid culture does have its drawbacks such as contamination; to minimise these risks it’s essential that a sterile working space and equipment be maintained when conducting liquid culture experiments.
Some cultures include additives to regulate acidity or stabilize sugars, helping prevent caramelization during sterilization. Experimenting with different combinations is recommended until finding one that fits best for your liquid culture recipe.
Once your nutrient solution has reached its optimal results, sterilize your chosen container. This could range from a glass jar or plastic spawn bag with injection ports (for oyster mushrooms) or wood chips; other growers use special “airport” lids with self-healing injection ports and air exchange filters that make inoculation with syringe easier; such lids are even available for mason jars – providing a convenient option for smaller-scale liquid cultures.
Incubation
As liquid cultures do not form on a horizontal plane like agar does, contamination can be difficult to spot and spread over time. To minimize potential issues with liquid cultures it is necessary to have a sterile working environment and clean equipment in place in order to minimize contamination risks.
An easy liquid culture recipe comprises distilled water mixed with honey or light malt extract (LC). This solution should contain no more than 4% sugar to prevent mycelium growth from being inhibited or killed off altogether. Supplements can also be added such as protein, lipids, starches, minerals or vitamins for optimal growth of mycelium colonies.
To inoculate a new medium with your LC, utilize aseptic techniques to transfer spore colonies from their original containers into fresh nutrients solutions. A syringe is recommended because it offers easy control and minimizes contamination; when using needles instead it must first be sterilized over a flame until its red glow returns before use. Having multiple sets of syringes handy will also come in handy in case multiple batches need inoculating simultaneously.
Monitoring
Regularly inspect the jars for signs of mycelium growth. It typically takes 2-7 days for visible clumps of mycelium to form and up to several weeks until full colonization has taken place, depending on species and conditions.
Regular agitation of liquid cultures is vital in breaking up and dispersing mycelial mass throughout. A magnetic stir bar or clean glass marble may be used to gently shake the jars. When not immediately used, store in the refrigerator to slow mycelial metabolism and prolong shelf life.
Maintaining a productive mushroom liquid culture is an integral component of home cultivation. If your liquid culture becomes cloudy, changes color or smells strange, it could contain bacteria or mold and needs to be disposed of to avoid spreading to other cultures. With time and care, mastering liquid culture may provide more efficient ways of creating and inoculating grain substrate and agar media substrates.