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Bacteriophage Mixture Inactivation Kinetics against E scherichia Coli O 157: H 7 on Hard Surfaces
Author(s) -
Viazis Stelios,
Labuza Theodore P.,
DiezGonzalez Francisco
Publication year - 2015
Publication title -
journal of food safety
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 43
eISSN - 1745-4565
pISSN - 0149-6085
DOI - 10.1111/jfs.12160
Subject(s) - kinetics , bacteriophage , chemistry , escherichia coli , polyethylene , agar , nuclear chemistry , microbiology and biotechnology , chromatography , biology , bacteria , biochemistry , physics , organic chemistry , genetics , quantum mechanics , gene
This study determined the effect of previously described phage cocktail ( BEC 8) on the inactivation kinetics of a mixture of E scherichia coli ( EHEC ) O 157: H 7 strains on food processing surface materials: stainless steel chip ( SSC ), ceramic tile chip ( CTC ) and high‐density polyethylene chip ( HDPEC ). EHEC strains were combined and spot‐inoculated on surfaces in dried or liquid form and BEC 8 was applied and incubated at 12, 23, 30 and 37C. EHEC survival was determined on tryptic soy agar. D values ranged from 3.9 min at 37C to 46.7 min at 12C. Z values calculated for SSC , CTC and HDEPC resulted in 26.1, 23.7 and 26.7C for dry cells, respectively, and 23.2, 23.7 and 24.5C for liquid cells, respectively. There was a significant difference in the rate of bacterial inactivation between lower (12 and 23C) and higher temperatures (30 and 37C). These results indicated that BEC 8 killed EHEC on hard surfaces rapidly following first‐order kinetics. Practical Applications The effect of a previously described phage cocktail ( BEC 8) on the inactivation kinetics of a mixture of E scherichia coli ( EHEC ) O 157: H 7 strains applied on hard food processing surface materials was studied. The results indicated that phages killed EHEC on hard surfaces relatively rapidly following a predictable rate. However, one must consider the long times to achieve a 5‐log reduction when initial cell counts are high. It would take approximately 2–4 h for a 5‐log cfu reduction of liquid cells at 23C. Both the time length and the temperature of application must fit within the industry time scales.