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ENRICHMENT OF SEVERELY AND MODERATELY HEAT‐INJURED LISTERIA MONOCYTOGENES CELLS
Author(s) -
WANG SHUYING,
HITCHINS ANTHONY D.
Publication year - 1994
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.1745-4565.1994.tb00598.x
Subject(s) - listeria monocytogenes , food science , listeria , strain (injury) , microbiology and biotechnology , population , yeast extract , bacteria , biology , chemistry , sodium pyruvate , yeast , tryptic soy broth , biochemistry , fermentation , medicine , anatomy , genetics , environmental health
Recovery of injured cells of a 90% heat kill of Listeria monocytogenes strain Lm82 in Trypticase soy yeast extract broth (TSBYE) at 30C was determined in enrichment broth and modified enrichment broth. Although the surviving population was heterogeneous with respect to degree of damage, two fractions of surviving cells defined as moderately and severely damaged were considered. Progeny of moderately damaged survivors (NaCl‐sensitive but not enrichment medium‐sensitive) increased about 100‐fold in 5 h; severely damaged cells (enrichment medium‐ and NaCl‐sensitive) did not grow in this time period. Most of the severely damaged cells required 20 h or longer to recover in TSBYE and even longer in TSBYE plus selective agents. Recovery was accelerated either by adding sodium pyruvate or by reducing the oxygen level. The results were used to design a Mark I preenrichment/enrichment protocol based on the U.S. Food and Drug Administration's selective enrichment broth.