Liquid culture jars make an excellent starting point for mushroom cultivation. Quick to sterilize and maintain, they offer consistent nutrition to support mycelium development.
Prep a large glass jar by wrapping in foil and heating in a pressure cooker until pressure reaches 15psi. Ensure all items such as lighter, syringe and substrate-filled spawn bag have been sterilized before adding your mix.
Liquid culture in mushroom growing is a sterilized nutritious solution in which spores are added to create mycelium colonies that will then inoculate substrates for mushroom cultivation.
Liquid culture recipes typically consist of mixing water with honey or light malt extract to provide nutrients to mycelium, in a sealed jar with self-healing injection ports and gas exchange filters for mycelia growth. Airport (commonly referred to as grain spawn) jars are often chosen due to their seal that includes self-healing injection ports and gas exchange filters.
Ideal mycelia growth requires daily stirring with the use of a stir plate for maximum efficiency and minimal damage to liquid mycelial colonies. This agitation should take place daily.
Agar is a solid, nutrient-rich medium used in various cultures. You can purchase premade mixes or components individually; instructions typically accompany either purchase option.
Once a culture is fully colonized on agar, it can be transferred into a jar full of nutrient-rich broth for further expansion into grains or wood chips as an inoculant substrate.
To do this, you will require a sterilized needle or scalpel and flame sterilize it until its blade glows red in an oven. Next, open up your agar plate lid while keeping your hand downstream of it to ensure laminar flow, then quickly cut a small piece of agar using the sterilized blade.
Although Karo syrup is delicious, it does have one major drawback: Clostridium botulinum can lead to botulism – a potentially lethal disease which requires keeping workspace and equipment sterile to prevent contamination. To ensure success in liquid culture environments, keeping these areas sterile is crucial.
To create nutrient-rich mushroom liquid medium, combine Karo, peptone and light malt extract in a pot until thoroughly mixed, before placing each jar in a pressure cooker to sterilize it. Upon sterilization of each jar, an injection syringe with mycelium-inducing spores should be injected directly into each one and left incubate for several weeks until mycelium colonies fill out their respective liquid medium.
Peptone is a protein-based ingredient used in mushroom cultivation. It consists of hydrolyzed proteins from either plant or animal sources combined with water to form an ideal nutritional medium for this fungi culture.
Fungi are often grown in liquid culture on this medium and used as substrate for various tests such as indole detection using Kovacs or Ehlrich reagent, microbial enumeration, and the oxidation-fermentation test for Vibrio species.
As well as its use as a nitrogen source in various nutrient broths for microorganisms, sodium chloride provides nutrients and electrolytes essential to their growth. Once mixed together, this mixture must be sterilized using heat sterilization before being filtered for use.
5. Light Malt Extract
Most beginning home brewers start off using malt extract (see From the Glass, January/February 2016 Zymurgy). Some may use it for timesaving convenience until they learn to mash grain.
Liquid malt extract has several advantages over dry extract in terms of stability. One such advantage is being easy to measure out without using an entire package because its powder form doesn’t need dissolving before measuring is made easier.
To make enough liquid to fill a Petri dish sleeve, combine 1g LME and 500ml water, pressure cook for 30 minutes at 15 PSI and sterilize your jar afterwards.
6. Potato Broth
Potato broth can be an economical and readily accessible way to reduce contamination in liquid culture environments, as it contains both glucose and other sugars which support sporulation if using honey as the liquid culture medium.
Add enough distilled water to bring the volume up to one liter, before stirring in agar powder, dextrose and yeast extract until everything has dissolved completely before sterilizing and long-term storage of your liquid culture.