How to Grow Mushrooms From Spores

A collection of Agaricus Mushrooms

Mushrooms can be grown from spores or from tissue culture. Spore culture results in a genetically diverse mushroom population. Spore culture is useful when isolating and testing new strains. Procedures for growing mushrooms are species-specific. It is assumed that the grower knows how to grow a particular mushroom of interest once sufficient spawn is obtained.

Things You'll Need

• Mushroom spores Malt extract agar (MEA) Petri dishes (plates) Species-suitable substrate Alcohol lamp Inoculating loop Sodium chloride solution (0.9 percent W/V) Pressure cooker Test tubes Erlenmeyer flasks Parafilm or plastic wrap Jars or bags for spawn production

Instructions

Preparing the Materials

1. Prepare 500-1000 ml of MEA in accordance with the manufacturer's instructions.

2. Place the sodium chloride solution in test tubes and the MEA in Erlenmeyer flasks. Do not fill tubes and flasks more than half-full and cap loosely.

3. Sterilize the sodium chloride solution, MEA and Petri dishes (if unsterile) in a pressure cooker at 121 degrees C and 15PSI for 15 to 20 minutes.

4. Remove MEA, sodium chloride solution and Petri dishes from the pressure cooker and allow to cool.

5. When the MEA has cooled enough to handle, but before it solidifies, carefully lift the cover of each Petri dish, pour in 10 to 20 ml of molten MEA.

6. Let MEA plates and sodium chloride cool to room temperature.

Plating the Spores

1. Sterilize the loop in an alcohol flame. Let the wire get red hot, then cool for 5 seconds.

2. Dip the loop into the sodium chloride solution to collect a drop of fluid. Spread the drop over a small area on the spore print (or other source of spores) to create a liquid/spore mixture. Repeat several times, sterilizing the loop in between.

3. Dip the loop into the sodium chloride/spore suspension to collect spores in the loop.

4. Lift the cover of an agar plate just far enough to allow access of the loop.

5. Smear the spore suspension in the loop over the surface of the agar, and recover the plate. Repeat for as many plates as desired (at least five or six).

6. Seal the agar plates with Parafilm or plastic wrap to prevent drying. Incubate the spores at temperature and light conditions suitable for the species.

7. 

   Observe the plates every few days to look for germination. White fuzzy growth (a mycelium) on the agar surface indicates the presence of a fungus (but it might not be a fungus that grew from the spores).

Isolating a Pure Culture

1. Compare the mycelium with published descriptions of the mycelium you are trying to grow.

2. If the mycelium looks as expected, purify the culture by cutting out pieces and transferring to fresh agar plates.

3. Continue cutting out pieces from the leading edge of the expanding colonies until a pure, bacteria-free, isolate is obtained.

Spawn Preparation

1. Cut out and transfer pieces of purified mycelium into jars of sterilized grain or wood chip substrate. The type of substrate used depends on the mushroom species.

2. Incubate the spawn masters in conditions suitable for the species, until the substrate is fully colonized with mycelium.

3. Periodically shake the spawn containers to break up the substrate and speed colonization.

4. Use the spawn masters to inoculate other spawn containers to produce more spawn.

Inoculating the Mushroom Growing Substrate

1. Shake the spawn containers vigorously to break up the spawn.

2. Pour the spawn into bags or trays of mushroom growing substrate.

3. Thoroughly mix the spawn into the substrate by stirring or shaking.

4. Proceed according to published methods for growing out the mycelium and initiating fruiting for the species under cultivation.

Tips & Warnings

• Work quickly when pouring agar or transferring inoculum to reduce contamination. Time and effort can be saved by purchased pre-poured and sterile agar plates. MEA is a good general purpose medium for growing fungi, but another type of medium may be more appropriate depending on the mushroom species.

• Pressure cookers get hot and can cause injury. Follow the manufacturer's maintenance and operation instructions. Sterilized media containers are hot and must be handled with heat resistant gloves to avoid burns and spills. Leave caps and lids of containers being sterilized loose to allow pressure equalization during heating and cooling. All containers to be sterilized must be made of autoclavable material.

References

• Growing Gourmet and Medicinal Mushrooms; 1993, Paul Stamets; Ten Speed Press; Berkeley, CA

Resources

• Mushroom Growing Supplies at Fungi Perfecti