title: Persistent and non-persistent strains of Listeria monocytogenes: A focus on growth kinetics under different temperature, salt, and pH conditions and their sensitivity to sanitizers.
abstract: This study aimed to investigate the effect of different conditions, including temperature (37 °C, 22 °C, and 4 °C), NaCl concentrations (2.5%, 4%, and 8%), and acidity (pH = 5), on the growth response of persistent and non-persistent isolates of Listeria monocytogenes. The resistance to two common sanitizers (benzalkonium chloride and hydrogen peroxide) was also investigated. A selected group of 41 persistent and non-persistent L. monocytogenes isolates recovered from three cheese processing plants during a previous longitudinal study was assembled. Average lag time was similar for persistent and non-persistent isolates grown at 37 °C, 22 °C and 4 °C but significantly shorter (p < 0.05) for persistent isolates grown at 2.5%, 4% and 8% NaCl, and at pH 5. Average growth rates were significantly higher (p < 0.05) for persistent than for non-persistent isolates when grown at 22 °C, 2.5%, 4% and 8% NaCl, and at pH 5. These results suggest that persistent strains may be better adapted to grow under stressful conditions frequently encountered in food processing environments than non-persistent strains. No relation between persistence and resistance to the tested sanitizers was found.
authors.affiliation: Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal.
authors.forename: R
authors.initials: R
authors.lastname: Magalhães
authors.affiliation: Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal.
authors.forename: V
authors.initials: V
authors.lastname: Ferreira
authors.affiliation: Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal.
authors.forename: T R S
authors.initials: TR
authors.lastname: Brandão
authors.affiliation: Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal.
authors.forename: R Casquete
authors.initials: RC
authors.lastname: Palencia
authors.affiliation: Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal.
authors.forename: G
authors.initials: G
authors.lastname: Almeida
authors.affiliation: Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina, Laboratório Associado, Escola Superior de Biotecnologia, Rua Arquiteto Lobão Vital, Apartado 2511, 4202-401 Porto, Portugal. Electronic address: pcteixeira@porto.ucp.pt.
authors.forename: P
authors.initials: P
authors.lastname: Teixeira
mesh_terms: D001548:Benzalkonium Compounds / Q000494:pharmacology; D002611:Cheese / Q000382:microbiology; D015169:Colony Count, Microbial; D004202:Disinfectants / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008089:Listeria monocytogenes / Q000737:chemistry / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism; D012965:Sodium Chloride / Q000378:metabolism; D013696:Temperature
chemical_list: D001548:Benzalkonium Compounds; D004202:Disinfectants; D012965:Sodium Chloride; D006861:Hydrogen Peroxide
keywords: Growth; Hydrogen peroxide; Listeria monocytogenes; Microtiter plate assay; Persistent; Quaternary ammonium compounds; Sanitizers; Stress; Temperature