ORIGINAL ARTICLE Characterization and genome sequence of Dev2, a new T7-like bacteriophage infecting Cronobacter turicensis Michal Kajsı ´k • Lucia Oslanecova ´ • Toma ´s ˇ Szemes • Michalea Hy ´blova ´ • Andrea Bilkova ´ • Hana Drahovska ´ • Ja ´n Turn ˇa Received: 5 March 2014 / Accepted: 30 June 2014 / Published online: 15 July 2014 Ó Springer-Verlag Wien 2014 Abstract Cronobacter spp. are opportunistic pathogenic bacteria that are responsible for severe infections in neo- nates. Powdered infant formula was confirmed to be the source in some cases. Bacteriophages offer a safe means for eliminating this pathogen. In the present study, we investigated the growth parameters and genome organiza- tion of a new bacteriophage, Dev2, isolated from sewage. The Dev2 phage contains DNA with a length of 39 kb and belongs to the T7 branch of the subfamily Autographivir- inae, with the highest degree of identity to the phage K1F. The host specificity of Dev2 is limited to C. turicensis strains of the CT O:1 serotype. With a lower efficiency, this phage also infects some Salmonella and E. coli strains. The Dev2 phage can inactivate sensitive Cronobacter strains in reconstituted milk formula. The results obtained in this study are an important prerequisite for application of Dev2 in food control. Introduction Cronobacter spp. are opportunistic pathogenic bacteria that can cause serious infections in neonates, including meningitis, necrotising enterocolitis and sepsis, with low frequency but a high lethality rate [14, 26]. Infections in adults also have been reported, in particular among the elderly and immunocompromised patients [11]. Whereas Cronobacter has been isolated from various foods and environments [19, 32], the main vehicle for its transmission in neonatal infections is rehydrated powdered infant for- mula (PIF) [15, 34]. The ubiquitous occurrence of Cro- nobacter strains makes control of this pathogen difficult [13, 35]. One possibility to solve problems involving pathogen contamination in food is utilization of bacteriophages, due to their high specificity and efficiency [12, 29]. However, before application, it is necessary to obtain sufficient information about the biocontrol phages to guarantee their safety and reliability [29, 36]. Presently, several Cronob- acter phages with sequenced genomes have been reported, including nine myoviruses [1, 2, 22–24, 27], two siphovi- ruses [21, 25] and two podoviruses [3]. Phage vB_CsaM_GAP161 belongs to the T4-like group of the family Myoviridae and is able to infect a broad spectrum of Cronobacter strains including representatives of C. sak- azakii, C. malonaticus, C. dublinensis and C. muytjensii. Recently, this phage was also succefully used for phage therapy of C. sakazakii infection in a G. mellonella larvae animal model [2, 4]. Bacteriophage vB_CsaM_GAP31 from the V5-like group of phages is another broad-host- spectrum myovirus. It was able to lyse 11 of 14 tested C. sakazakii strains [1]. A similar phage, Cr3, was described to be specific for C. sakazakii strains expressing bacterial flagella [27]. Virulent phage ESP2949-1 was isolated from sewage on the C. sakazakii ATCC29544 indicator strain and was found to be related to enterophages T1 and TLS from the family Siphoviridae [24]. Two other virulent phages, ES2 and ESSI-2, were isolated on the same M. Kajsı ´k Á L. Oslanecova ´ Á M. Hy ´blova ´ Á H. Drahovska ´(&) Á J. Turn ˇa Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Mlynska ´ dolina 1, 84215 Bratislava, Slovakia e-mail: drahovska@fns.uniba.sk T. Szemes Geneton Ltd., Bratislava, Slovakia A. Bilkova ´ Faculty of Pharmacy, Comenius University, Bratislava, Slovakia 123 Arch Virol (2014) 159:3013–3019 DOI 10.1007/s00705-014-2173-5