GROWING GOURMET - Anto2ni.it

134 GENERATING GRAIN SPAWN
Figure 107. Cutting mycelium from the nutrient
agar medium.
ing a sterilized scalpel. Prior to this activity, the
space where the transfers are to take place has
been aseptically cleaned. The hopeful spawn
maker has showered, washed, and adorned
newly laundered clothes. Immediately prior to
doing any set of inoculations, the cultivator
washes his hands and then wipes them with 80%
rubbing alcohol (isopropanol). If working in
front of a laminar flow hood, the freshest, sterilized
material is kept upstream, with the
mycelium directly downstream. The cultivator
prioritizes items on the inoculation table by degree
and recentness of sterility. The same
attention to movement that was used to inoculate
nutrient-filled petri dishes in Chapter 12 is similarly
necessary for successful production of grain
spawn. Attention to detail, being aware of every
minute movement, is again critical to success.
Steps for Generating Grain
Spawn Masters
Step 1. Visually ascertain the purity of a
mushroom culture, selecting a petri dish culture
showing greatest vigor. Ideally, this culture
should be no more than two weeks old, and
there should be a margin of uncolonized media
along the inside peripheral edge. This
uncolonized zone, approximately 1/2 inch (1.
30 cm.) in diameter, can tell the cultivator
whether or not any viable contaminant spores
have recently landed on the media. Once the
mycelium has reached the edge of the petri dish,
any contaminant spores, should they be present,
lie dormant and invisible upon the mushroom
mycelium only to wreak havoc later.
Step 2. Although the contents within maybe
sterilized, the outer surface of the pressure
cooker is likely to be covered with contaminants
which can be transferred via hand contact.
Therefore, the outside of the pressure cooker
should be thoroughly wiped clean prior to the
sterilization cycle. Open the pressure cookerin
the laboratory clean room. Ideally, the pressure
cooker has formed a vacuum in cooling. If the
pressure cooker in use does not form a vacuum,
outside air will be sucked in, potentially contaminating
the recently sterilized jars. The
pressure cooker should be placed in the clean
room directly after the sterilization cycle and
allowed to cool therein. (I usually place a paper
towel saturated with isopropanol over the
vent valve as an extra precaution, to filter the air
entering the pressure cooker.) Another option
is to open the pressure cooker in front of a laminar
flow bench at the moment atmospheric
pressure is re-achieved. Remove the sterilized
grain jars from the pressure cooker. Place the
grain-filled jars upstream nearest to the laminar
flow filter. Then sterilize the scalpel by
flaming until red hot.
Step 3. Directly cut into the petri dish culture
(The blade cools instantly on contact.) Drag the
blade across the mycelium-covered agar, creat-
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