GROWING GOURMET - Anto2ni.it

92
CULTURING MUSHROOM MYCELIUM ON AGAR MEDIA
End-Substrate Supplements
3-5 grams sawdust
3-5 grams powdered straw
3-5 grams sugar cane bagasse, etc.
Until some familiarity is established, the purchase
of pre-mixed media from reputable
companies is advised. Be forewarned, however,
that the media designed for the growth of imperfect
fungi, available from large laboratory
supply companies, favors the growth of mold
contaminants over that of mushroom mycehum.
The media for most saprophytes should
be adjusted to a pH of 5.5 to 6.5. Most
saprophytes acidify substrates, so near neutral,
even basic, substrates, become more acidic as
the mushroom life cycle progresses.
Pouring Agar Media
One liter of malt extract agar medium will
pour 20-40 100 x 15 mm. petri dishes, depending
upon the depth of the pour. Before pouring an
agar medium, the table top is thoroughly wiped
clean with an 80% concentration of isopropanol
(isopropyl alcohol). Plastic petri dishes usually
come pre-sterilized and ready to use. Glass petri
dishes should be first washed and sterilized in a
petri dish-holding rack simultaneous to the sterilization
of the agar medium in an autoclavable
flask. Pre-pouring media into glass dishes and
then sterilizing is awkward. Media separation
occurs, and any movement during the sterilization
cycle (or while transferring the pressure
cooker to the clean room) causes the liquifled
media to spill out of the petri-dishes. A huge
mess results. However, this problem can be
avoided if the pressure cooker cools overnight,
for instance, and is then opened the next day. Be
forewarned that if you choose this alternative,
your pressure cooker must either form a vacuum,
safely protecting the media before opening, or be
placed into a HEPA filtered airstream to prevent
contamination entry during cool-down.
Figures 68-69. Pouring malt agar into sterile petri dishes in front of laminar flow hood.
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