Micro December 2018

A total of 30 closely related non- E. coli species and 30 isolates of non-coliform species were 1

cultured in Brain heart infusion broth at 37 ± 2°C for 20–24 h. 2

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Isolates from the following sources were used in the study: American Type Culture

Collection (ATCC), Manassas, VA; Q Laboratories Culture Collection (QL), Cincinnati, OH; NITE 4

Biological Resource Center (NBRC), Tokyo, Japan; National Collection of Type Cultures, 5

Salisbury, UK; and 3M Food Safety Center, St. Paul, MN. Inclusivity and exclusivity cultures each 6

were serially diluted in BPBD, randomized, blind-coded and then plated in triplicate onto 3M 7

Petrifilm Rapid E. coli /Coliform Count Plates. For each isolate, a plate was incubated at 32 ± 1°C, 8

35 ± 1°C, and 42 ± 1°C for 18–24 h. Isolates were also plated onto Violet Red Bile (VRB) with 9

VRB plus 4-methyl-umbelliferyl- β -D-glucuronide (MUG) overlay for comparison to BAM Ch. 4 10

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and incubated at the same temperatures for 18–24 h.

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In addition, inclusivity and exclusivity cultures each were serially diluted in PSS, randomized,

blind-coded and then plated in triplicate onto 3M Petrifilm Rapid E. coli /Coliform Count Plates. 13

For each isolate, a plate was incubated at 30 ± 1°C, 37 ± 1°C and 42 ± 1°C for 18–24 h. The 14

coliform inclusivity and exclusivity isolates were also plated onto VRBL agar for comparison to 15

ISO 4832:2006. Plates were incubated at the same temperatures for 24 ± 2 h. The E. coli 16

inclusivity and exclusivity isolates were also plated onto Tryptone Bile X-glucuronide medium 17

(TBX) for comparison to ISO 16649-2:2001. Plates were incubated at 30 ± 1°C, 37 ± 1°C and 44 ± 18

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1°C for 18–24 h.

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Inclusivity/Exclusivity Testing Results

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