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SIMPLE oPSU BROTH‐BAX® PCR‐PICOGREEN® SYSTEM FOR RAPID DETECTION OF LISTERIA MONOCYTOGENES IN PASTEURIZED MILK AND HOT DOGS
Author(s) -
PARAMESWARAN SANGEETHA,
GUYER ROBERT B.,
KNABEL STEPHEN J.
Publication year - 2003
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/j.1745-4565.2003.tb00367.x
Subject(s) - pasteurization , listeria monocytogenes , microbiology and biotechnology , lysis , food science , biology , chemistry , chromatography , bacteria , genetics
ABSTRACT Factors that significantly affect BAX® PCR detection of Listeria monocytogenes from optimized Penn State University (oPSU) broth were identified and optimized. Concentration of PCR product was significantly reduced by BAX™ protease and significantly increased by eliminating the lysis step and directly diluting oPSU broth prior to PCR. A simple oPSU broth‐BAX® PCR‐PicoGreen® (PSU‐BAX‐PicoGreen) system was developed and compared with current methods for detecting low levels of L. monocytogenes in commercial milk and hot dogs. All 30 milk samples inoculated with 10–20 CFU per mL L. monocytogenes were positive by FDA, BAX® and PSU‐BAX‐PicoGreen methods and all 42 uninoculated milk samples were negative by all of the above methods. All 30 hot dog samples inoculated with 10‐20 CFU/g L. monocytogenes were positive by the USDA and PSU‐BAX‐PicoGreen methods, however, 2 hot dog samples gave indeterminate results with the standard BAX® method. All 42 uninoculated hot dog samples were negative by USDA, 9 were indeterminate by BAX® and 2 were positive by PSU‐BAX‐PicoGreen. The PSU‐BAX‐PicoGreen system may provide a simple and accurate method for rapidly screening pasteurized foods for both injured and noninjured L. monocytogenes.