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3M Petrifilm SALX Collaborative Study
July 2013
OMA-2013-July-XXX
DRAFT DOCUMENT
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Spread the diluent over the entire 3M Petrifilm SALX Plate growth area before
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the gel is formed. Do not slide the spreader across the film (figure D).
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5.7.6
Remove the spreader and leave the 3M Petrifilm SALX Plate undisturbed for at
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least 1 minute.
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5.7.7
Place 3M Petrifilm SALX Plate on a flat surface for at least 1 hour at room
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temperature (20-25°C / <60% RH), protected from light, to allow the gel to form.
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Hydrated 3M Petrifilm SALX Plates can be stored at room temperature (20-25°C
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/ <60% RH) for up to 8 hours before use if protected from light,. If hydrated 3M
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Petrifilm SALX Plates will not be used within 8 hours, seal them in a plastic bag,.
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protected from light and store at -20 to -10°C for up to 5 days.
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5.7.8
After 3M Petrifilm SALX Plates are removed from storage, allow them to warm
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to room temperature before use.
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5.8
Plate Inoculation
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5.8.1
Remove the enrichment medium from the incubator and agitate contents by
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gentle hand massage.
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5.8.2
Use a sterile 10 µL loop (3 mm diameter) to withdraw each sample. Use a
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smooth loop (one that does not have jagged edges and is not distorted) to
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prevent the gel surface from breaking.
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5.8.3
Open the 3M Petrifilm SALX Plate and streak onto the gel (figure E). Perform a
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single streak to obtain isolated colonies (Figure 1).
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Figure 1:
Streaking pattern on the 3M Petrifilm SALX Plate
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5.8.4
Roll down the top film to close the 3M Petrifilm SALX Plate.
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5.8.5
Using a gloved hand (while practicing good laboratory practices to avoid cross
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contamination and/or direct contact with the plate), gently apply a sweeping
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motion with even pressure onto the top film to remove any air bubbles in the
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inoculation area (figure F).
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5.9
Plate Incubation
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5.9.1
Incubate plates at 41.5 ± 1.0°C for 24 hours ± 2 hours in a horizontal position
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with the colored side up in stacks of no more than 20 plates.
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OMAMAN-08/Collaborative Study Protocol
March 2014
Expert Review Panel Use Only
AOAC Research Ins itute
Expert Review Panel Use Only