Agar plates (enriched with fruit juice)
MATERIALS
Reagents
32 g agar
16.6 g sucrose
300 mL fruit juice (apple or grape)
Equipment
Beaker
Graduated cylinder
Hot plate
Petri dishes (5 cm)
Pipettes
Scale
METHOD
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1. Combine the first three ingredients. Add H2O to 1 L.
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2. Boil the ingredients while stirring on a hot plate at high setting (the solution will foam and rise; it may be necessary to take it off the heat and put it back a couple of times before fully dissolving the agar).
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3. Cool to touch.
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4. Prepare a mixture of propionic acid:phosphoric acid (9:1). Add 5 mL of this to the cooled mixture and stir.
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5. Pour into 5-cm Petri dishes. Keep the lids off the plates for 10 min.
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6. Cover and store the plates at 4°C.
