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Thermal resistance of wild‐type and antibiotic‐resistant Listeria monocytogenes in meat and potato substrates
Author(s) -
Walsh D.,
Sheridan J.J.,
Duffy G.,
Blair I.S.,
McDowell D.A.,
Harrington D.
Publication year - 2001
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1046/j.1365-2672.2001.01284.x
Subject(s) - listeria monocytogenes , food science , listeria , microbiology and biotechnology , heat resistance , antibiotic resistance , biology , heat shock , heat shock protein , chemistry , antibiotics , bacteria , materials science , gene , biochemistry , genetics , composite material
Aims: This study aimed to elucidate the relationship, if any, between the acquisition/possession of antibiotic resistance in strains of Listeria monocytogenes and the resistance of such strains to heat stress. Methods and Results:D ‐values calculated using a linear survival model were used to compare the heat resistance of two wild‐type (WT) and two antibiotic (streptomycin)‐resistant (AR) mutant strains of L. monocytogenes measured in minced beef and potato substrates at 55°C, with and without prior heat shock at 48°C. In both minced beef and potato, no significant differences ( P < 0·05) between D ‐values of AR and WT strains were noted. Heat shock did not significantly increase D ‐values of WT or AR strains in minced beef, while in potato slices, D ‐values in almost all cases were significantly higher in samples which had received heat‐shock treatment. In minced beef, the use of a non‐selective/overlay recovery medium did not result in higher D ‐values for any strains, while in potato, significantly higher ( P < 0·05) D ‐values were obtained in most cases. Conclusions: The presence or absence of antibiotic resistance genes did not modulate the heat resistance of the strains examined in this study. Significance and Impact of the Study: The study demonstrated that heat shock, and the type of media used to determine bacterial numbers during heat processing, can significantly affect the D ‐values obtained.