Perhaps this will be the year when
you devote a corner of your garden to growing your own portabellas,
criminis, shitakes, shaggy manes, Lepiotas, oysters, enokitakes.
In this column we will give a basic outline of mushroom cultivation
techniques and try to answer your questions about cultivation.
Each article will briefly cover a different aspect of mushroom
cultivation:
- Growth on Agar
- Growth on Grain
- Growth on Compost
- Pests and Diseases Plus Culture
Maintenance
- Growth on Logs
I hope cultivation corner will provide stimulus and help you
establish your own cultivation corner. Happy hunting and growing!
I. Growth on Agar:
The first phase of mushroom cultivation is the isolation of
a pure culture of mycelium. Nutrient agar provides the medium
on which this takes place. The two most commonly used nutrients
agars for mushroom cultivation are Potato Dextrose (Yeast) Agar
(PD(Y)A) and Malt-Extract Agar (MEA). Potato Dextrose (Yeast)
Agar is most often used for tissue culture and Malt-Extract Agar
is usually the medium of choice for spores.
PD(Y)A should be sterilized for 45 minutes at 15 pounds pressure.
MEA should be sterilized for 30 minutes at 15 pounds pressure.
Sterilization of MEA for more than 30 minutes can lead to caramelization
of the malt sugars. Most mushrooms prefer a neutral to slightly
acid pH. That is a pH of 5.5 to 7.0. These two recipes should
result in medium within this pH range without further adjustment.
Petri dishes, baby bottles and baby food jars all make good containers
for agar.
Potato Dextrose (Yeast) Agar (PD(Y)A):
Potato Water 1 liter
Dextrose 10 grams
Nutritional Yeast or Yeast Extract 1-3 grams (optional) Agar-
agar 20 grams Potato water is prepared by boiling a large, washed
but not peeled, thinly sliced potato in water for one hour. The
potato water is strained, brought to one liter of volume and
the other ingredients then added prior to sterilization. Malt-Extract
Agar (MEA) Malt- extract 15 grams. Agar-agar 20 grams
Water 1 liter Optional: Potassium biphosphate 0.1 gram and Calcium
carbonate 0.1 gram Inoculation of Agar for Culture Isolation:
Mycelia can be gotten from spores or tissue culture. Tissue cultures
may be taken from any clean portion of the mushroom using a sterilized
exacto knife or surgical blade. Spores may be started form pieces
of gill tissue, spore prints, or direct spore drops onto to agar
made by placing a portion of the mushroom with the gills toward
the agar surface on the roof (cap, top,) of the petri dish using
a touch of Vaseline.
Commonly used spore isolation techniques include:
A. Streak Method:
Spores are transferred to one portion of the agar plate which
is then streaked across with an inoculation loop to another
portion of the plate in order to separate individual spores
and make the single colonies available for isolation.
B. Dilution
Method:
Spores are soaked in cooled sterilized distilled water for several
hours. Stir an inoculation loop in the spore solution and streak
the petri dish, or using a sterile eyedropper put a drop of the
spore solution onto the petri dish and spread. Agar to agar inoculations
can be easily done using sterile technique with an exacto knife,
surgical blade or an inoculating loop.
Once a pure culture of mycelium has been isolated, it is allowed
to take over the agar dish. With mycelium grown from single spores
it will be necessary to co-incubate two monokarotic cultures
in order to generate the dikaryotic culture needed to yield mushrooms.
This can be done by inoculating two pure spore cultures onto
the same agar plate, or by placing the two cultures into the
same jar of grain. If mycelium has been isolated by tissue culture
of a carpophore, you are now ready for transfer to grain media.
Next: Growing Mushrooms on Grain
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