title: A new and efficient method to obtain benzalkonium chloride adapted cells of Listeria monocytogenes.
abstract: A new method to obtain benzalkonium chloride (BAC) adapted L. monocytogenes cells was developed. A factorial design was used to assess the effects of the inoculum size and BAC concentration on the adaptation (measured in terms of lethal dose 50 -LD50-) of 6 strains of Listeria monocytogenes after only one exposure. The proposed method could be applied successfully in the L. monocytogenes strains with higher adaptive capacity to BAC. In those cases, a significant empirical equation was obtained showing a positive effect of the inoculum size and a positive interaction between the effects of BAC and inoculum size on the level of adaptation achieved. However, a slight negative effect of BAC, due to the biocide, was also significant. The proposed method improves the classical method based on successive stationary phase cultures in sublethal BAC concentrations because it is less time-consuming and more effective. For the laboratory strain L. monocytogenes 5873, by applying the new procedure it was possible to increase BAC-adaptation 3.69-fold in only 33 h, whereas using the classical procedure 2.61-fold of increase was reached after 5 days. Moreover, with the new method, the maximum level of adaptation was determined for all the strains reaching surprisingly almost the same concentration of BAC (mg/l) for 5 out 6 strains. Thus, a good reference for establishing the effective concentrations of biocides to ensure the maximum level of adaptation was also determined.
authors: Instituto de Investigaciones Marinas, Eduardo Cabello, 6. 36208 Vigo, Pontevedra, Spain.
authors: Paula
authors: P
authors: Saá Ibusquiza
authors: Juan J R
authors: JJ
authors: Herrera
authors: Daniel
authors: D
authors: Vázquez-Sánchez
authors: Adelaida
authors: A
authors: Parada
authors: Marta L
authors: ML
authors: Cabo
mesh_terms: D000220:Adaptation, Biological; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001431:Bacteriological Techniques / Q000379:methods*; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000302:isolation & purification*
chemical_list: D000900:Anti-Bacterial Agents; D001548:Benzalkonium Compounds