title: Growth of Escherichia coli O157:H7 and Listeria monocytogenes with prior resistance to intense pulsed light and lactic acid.
abstract: Previous study showed that repetitive mild decontamination treatments with intense light pulses (ILP) and lactic acid (LA) can induce increased resistance in surviving pathogenic cells. Research has evaluated the potential of increased resistance to enhance the persistence of resistant variants of Listeria monocytogenes and Escherichia coli O157:H7 under suboptimal growth conditions. Growth of resistant variants and parental strains was determined by optical density (OD) measurements in nutrient broths with different pH values and NaCl concentration, at low temperature. The real lag phase was calculated, and results indicated that intense light pulses (ILP) resistant variants needed longer time to initiate growth compared to their parental strains, for both L. monocytogenes and E. coli O157:H7 when incubated at 7 °C and 10 °C, respectively. These selected variants were of the similar resistance towards heat and low pH (no cross-tolerance). Nevertheless, lactic acid (LA) resistant variant of L. monocytogenes was cross-protected when exposed to low pH, but not when treated with heat.
authors.affiliation: Laboratory of Food Microbiology and Food Preservation, Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent, Belgium. Andreja.Rajkovic@UGent.be
authors.forename: Andreja
authors.initials: A
authors.lastname: Rajkovic
authors.forename: Nada
authors.initials: N
authors.lastname: Smigic
authors.forename: Frank
authors.initials: F
authors.lastname: Devlieghere
mesh_terms: D019453:Escherichia coli O157 / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000494:pharmacology*; D008027:Light; D008089:Listeria monocytogenes / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D050296:Microbial Viability / Q000187:drug effects / Q000528:radiation effects
chemical_list: D019344:Lactic Acid