GROWING GOURMET - Anto2ni.it

446 TROUBLESHOOTING
PROBLEM CAUSE SOLUTION
AGAR CULTURE
Media will not solidify Not enough agar
Insufficiently mixed
Add more agar> 20 grams/liter.
Agitate before pouring.
Bacteria
Increase sterilization time to at
least 30 minutes at 15 psi.
Spores will not germinate Inviable spores Obtain fresher spores.
Soak in 5 cc. of sterilized.
water for 48 hours.
Place one drop of spore
solution per petri dish.
Improperly formulated media See page 90.
Spores germinate with
mold contaminants
("powdery mildews")
Contaminated spores Isolate & transfer "white
spots" from one another to
new media dishes. Always
move mycelium away from
competitors.
Spores germinate with
bacterial contaminants
("slime")
Contaminated spores Use antibiotic media. (1/15 -
1/20 g/liter of gentamycin
sulfate). "Sandwich" spores
between two layers of antibiotic
media. Isolate mycelium
when it appears on top surface.
Mycelium grows then Poor Media Formulation See page 90.
dies back
Over-sterilized Media Sterilize for less than 1 hour
at 15 psi.
Poor strain
Acquire new strain.
Contaminants appear
along inside edge of
petri dish
Contamination airborne in
laboratory
Filter lab air, clean lab. Look
for source.
Wrap edges of petri dishes
with tape or elastic film after
pouring & inoculation.
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