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146 GENERATING GRAIN SPAWN
developed spore-mass inoculation techniques to
an industrial level. Only recently have Western
mycologists recognized that a large community of
spore matings behaves quite differently than
paired individuals. San Antonio and Hanners
(1984) are some of the first Western mycologists
to realize that grain spawn of Oyster
mushrooms could be effectively created via
spore-mass inoculation.
The most aggressive strains out-race the least
aggressive strains to capture the intended habitat.
Recent studies have shown that these
aggressive strains over-power and invade the
cellular network of competing strains. Dr. Alan
Rayner (1988) in studies at the University of
Bath, described this form of genetic theft as
"non-self fusions" between genetically different
mycelial systems within the same species.
This ability to adapt has made fungi one of the
most successful examples of evolution in the
biological arena.
Spore-mass fermentation techniques are not
yet widely used by North American or European
cultivators. Concern for preserving strain
stability, lack of experience, equipment, and intellectual
conflict are contributing factors. In
mushroom culture, intransigence to new ideas has
prevailed, often because the slightest variation
from the norm has resulted in expensive failures.
Liquid Inoculation
Techniques: Mycelial
Fragmentation and
Fermentation
This method differs from the spore-mass inoculation
techniques in that the starting
material is dikaryotic mycelium, not spores. In
short, the cultivator chops up the mycelium into
thousands of tiny fragments using a high speed
blender, allows the mycelium to recover, and
transfers dilutions of the broth into jars or bags
of sterilized grain. I prefer this technique as it
quickly generates high quality spawn, eliminating
several costly steps. Once perfected, most
spawn producers find grain-to-grain transfers
obsolete. The time not spent shaking the spawn
jars frees the cultivator to attend to other chores.
Most importantly, high-quality spawn is realized
in a fraction of the time of the traditional
methods. Step-by-step methods are described
in the ensuing paragraphs .The ambient air temperature
recommended throughout this process
is 750 F. (24° C.).
Step l.A vigorous, non-sectoring culture incubated
in a 100 x 15 mm. petri dish is selected.
This parent culture is subcultured by transferring
one-centimeter squares from the mother
culture to ten blank petri dishes. In effect, ten
subcultures are generated. The cultures incubate
until the mycelia reaches approximately 1
cm. from the inside peripheral edge of the petri
dish, more or less describing a 80 mm. diameter
mycelial mat.
Step 2. When the cultures have achieved the
aforementioned growth, use the following formula
to create a liquid culture media: After
mixing and subdividing 750 ml. of the broth
into three 1500 ml. Erlenmeyer flasks, the vessels
are placed within a pressure cooker
and sterilized for 1-2 hours at 15 psi (252° F.
=121° C.)*
* With experience, the cultivator will likely want larger
vessels for fermentation. I prefer a 5000-7000 ml.
squat glass flask, into which 2250 ml. of liquid
culture media is placed, sterilized, and inoculated
with 750 ml. of liquid inoculum. When the liquid
volume exceeds 5000 ml. additional measures are
required for adequate aeration, such as peristaltic
pumps pushing air through media filters. The surface
area of the liquid broth should be at least 110mm.!
2000 ml. for sufficient transpiration of gases and
metabolic by-products.
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