title: Bacteriophages with potential to inactivate Salmonella Typhimurium: Use of single phage suspensions and phage cocktails.
abstract: The aim of this study was to compare the dynamics of three previously isolated bacteriophages (or phages) individually (phSE-1, phSE-2 and phSE-5) or combined in cocktails of two or three phages (phSE-1/phSE-2, phSE-1/phSE-5, phSE-2/phSE-5 and phSE-1/phSE-2/phSE-5) to control Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) in order to evaluate their potential application during depuration. Phages were assigned to the family Siphoviridae and revealed identical restriction digest profiles, although they showed a different phage adsorption, host range, burst size, explosion time and survival in seawater. The three phages were effective against S. Typhimurium (reduction of ∼2.0 log CFU/mL after 4h treatment). The use of cocktails was not significantly more effective than the use of single phages. A big fraction of the remained bacteria are phage-resistant mutants (frequency of phage-resistant mutants 9.19×10(-5)-5.11×10(-4)) but phage- resistant bacterial mutants was lower for the cocktail phages than for the single phage suspensions and the phage phSE-1 presented the highest rate of resistance and phage phSE-5 the lowest one. The spectral changes of S. Typhimurium resistant and phage-sensitive cells were compared and revealed relevant differences for peaks associated to amide I (1620cm(-1)) and amide II (1515cm(-1)) from proteins and from carbohydrates and phosphates region (1080-1000cm(-1)). Despite the similar efficiency of individual phages, the development of lower resistance indicates that phage cocktails might be the most promising choice to be used during the bivalve depuration to control the transmission of salmonellosis.
authors.affiliation: Department of Biology and CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: Carla
authors.initials: C
authors.lastname: Pereira
authors.affiliation: Department of Biology and CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: Catarina
authors.initials: C
authors.lastname: Moreirinha
authors.affiliation: STAB VIDA-Investigação e Serviços em Ciências Biológicas, Madan Parque, 2825-182 Caparica, Portugal.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Lewicka
authors.affiliation: STAB VIDA-Investigação e Serviços em Ciências Biológicas, Madan Parque, 2825-182 Caparica, Portugal.
authors.forename: Paulo
authors.initials: P
authors.lastname: Almeida
authors.affiliation: STAB VIDA-Investigação e Serviços em Ciências Biológicas, Madan Parque, 2825-182 Caparica, Portugal.
authors.forename: Carla
authors.initials: C
authors.lastname: Clemente
authors.affiliation: Department of Biology and CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: Ângela
authors.initials: Â
authors.lastname: Cunha
authors.affiliation: Department of Chemistry & QOPNA, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Ivonne
authors.initials: I
authors.lastname: Delgadillo
authors.affiliation: Departamento de Microbiología e Parasitología, CIBUS-Facultad de Biologia, Universidade de Santiago de Compostela, Campus Vida s/n, 15782 Santiago de Compostela, Spain.
authors.forename: Jésus L
authors.initials: JL
authors.lastname: Romalde
authors.affiliation: CIIMAR/CIMAR-Centro de Investigação Marinha e Ambiental, Rua dos Bragas, 289, 4050-123 Porto, Portugal.
authors.forename: Maria L
authors.initials: ML
authors.lastname: Nunes
authors.affiliation: Department of Biology and CESAM, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal. Electronic address: aalmeida@ua.pt.
authors.forename: Adelaide
authors.initials: A
authors.lastname: Almeida
mesh_terms: D000818:Animals; D049872:Bivalvia / Q000382:microbiology; D058507:Host Specificity / Q000235:genetics* / Q000276:immunology; D050296:Microbial Viability; D009154:Mutation; D012483:Salmonella Phages / Q000254:growth & development / Q000472:pathogenicity*; D012486:Salmonella typhimurium / Q000235:genetics / Q000276:immunology / Q000821:virology*; D012623:Seawater / Q000737:chemistry; D017906:Siphoviridae / Q000254:growth & development / Q000472:pathogenicity*
keywords: Bacterial-phage inactivation; Phage cocktails; Phenotypic resistance; Salmonella Typhimurium; Salmonellosis