GROWING GOURMET - Anto2ni.it

Contaminants localized
to point of transfer
Contaminants appear
equally over the surface
of agar media
Media evaporates, cracks,
before colonization is
complete
GRAIN CULTURE
Grain spawn contaminates
before opening, before
inoculation
Mycelium does not grow Too dry
Culture contaminated
Scalpel contaminated
Airborne contamination
Contaminated media-
Insufficient sterilization
Hands upstream of
cultures during inoculation
in airstream of laminar
flow hood
Humidity too low
Culture in airstream
Bacteria endemic to grain
Contaminants enter during
cool-down
Bacterial contamination
TROUBLESHOOTING 447
PROBLEM CAUSE SOLUTION
Isolate new culture.
Flame sterilize scalpel longer.
Filter air & use good sterile
technique.
Increase sterilization time.
Keep hands downstream of
inoculation site.
Increase lab rH to 50% or wrap
petri dishes with tape or
elastic film.
Place cultures outside of
airstream.
Soak grain overnight to
trigger endospores into
germination, making them
susceptible to heat
sterilization.
Filter air during cool-down
or open pressure vessel at 1 psi
in clean room.
Over-sterilized. Cook 1-2
hours at 15 psi.
Reduce surface area or porosity
of filter media.
Soak grain spawn overnight.
Boil grain in a cauldron before
sterilization.
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