310 / 350
required for a yeast/mold Performance Tested Method submission, one is included here. The list is
1
abbreviated for the following reasons:
2
•
The antibiotic cocktail in the Petrifilm RYM Count Plate is the same as that for the current 3M™
3
Petrifilm™ Yeast and Mold Count Plate.
4
•
There have been no complaints filed for breakthrough of bacteria on the current plate.
5
•
The organisms selected represent both Gram positive and Gram negative organisms that are likely
6
to be detected if there was breakthrough.
7
8
Exclusivity Testing Methodology
9
The exclusivity portion consisted of quantifying 4 non-target (bacterial) organisms using the Petrifilm
10
RYM Plate method. Non-target (exclusivity) organisms were cultured in Tryptic Soy Broth (TSB) at
11
35 ± 1
o
C for 18 to 22 hours. Ten-fold serial dilutions for each culture were made 0.1%peptone water to
12
achieve a target inoculum of 100-150 CFU/mL. This was performed to verify that the target inoculum of
13
100-150 CFU/ml was achieved. The dilutions were then plated in triplicate onto Petrifilm RYM Plates and
14
into sterile Petri dishes, to which ~20 mL of sterile, tempered Tryptic Soy Agar (TSA) was added. The TSA
15
plates were swirled to mix and allowed to harden at room temperature.
16
The RYM plates were incubated at 25°C and enumerated at 48 and 60 hours. The TSA plates were
17
incubated at 32°C and the colonies enumerated at 48 hours. None of the four non-target organisms
18
were detected on the Petrifilm RYM Plates.
19
20
Table 10.
Exclusivity Organisms
21
Organism
Source
Escherichia coli
ATCC
25922
3M Culture Collection
Bacillus subtilis
ATCC
6633
3M Culture Collection
Aeromonas hydrophila
ATCC 7965
3M Culture Collection
Enterococcus faecalis
ATCC 14506
3M Culture Collection
22
23
Inclusivity/Exclusivity Results
24
The Petrifilm RYM Plate method was used to evaluate 42 target yeasts and molds and 4 non-target
25
organisms. All 42 target organisms produced typical (see colonial morphology descriptions listed in
26
14
AOAC Research Institute
Expert Review Panel Use Only
OMAMAN-16D/ PTM Report
ERP Use Only - December 2014