title: Growth of untreated and radiation-damaged Listeria as affected by environmental factors.
abstract: The growth of untreated Listeria monocytogenes 4ab No. 10 and that of the surviving fraction of its population treated with 0.8 kGy gamma rays was investigated in a microtitreplate system at incubation temperatures between 3 degrees C and 35 degrees C in Tryptic Phosphate Broth (TPB) or Brain Heart Infusion Broth (BHIB) media containing NaCl between 0.25 to 16.75% (w/v), and acidified with citrate-phosphate buffers to pH values between 4.63 and 7.06. The initial viable count was 3 x 10(3)/ml. Time periods to visible growth were recorded. Radiation survivors showed increased salt- and pH-sensitivities and increased minimum temperature for growth in TPB-based media. Adverse effects of sub-optimal environmental factors (reduced water activity, pH and temperature) and radiation injury were much less pronounced in BHIB-based media. Polynomial equations describing the combined effects of hydrogen ion and salt concentrations on the detectable growth at 30 degrees C were constructed for quantitative assessment of interactions. The results demonstrate that combining environmental stresses with low-dose irradiation can control growth of L. monocytogenes.
authors.affiliation: Department of Refrigeration and Livestock-Products Technology, University of Horticulture and Food Industry, Budapest, Hungary.
authors.forename: J
authors.initials: J
authors.lastname: Farkas
authors.forename: E
authors.initials: E
authors.lastname: Andrássy
authors.forename: L
authors.initials: L
authors.lastname: Mészáros
authors.forename: D
authors.initials: D
authors.lastname: Bánáti
mesh_terms: D003470:Culture Media / Q000494:pharmacology*; D004307:Dose-Response Relationship, Radiation; D005514:Food Irradiation; D005720:Gamma Rays; D006863:Hydrogen-Ion Concentration; D008089:Listeria monocytogenes / Q000187:drug effects / Q000254:growth & development / Q000528:radiation effects*; D009997:Osmotic Pressure; D013696:Temperature
chemical_list: D003470:Culture Media