ERANET (project: BIOMOS) and the Hungarian National Technology Program (projects FAGCNTER and MFCDiagn) also supported this work. The financial supports of HUSRB/1203/214/250 and PTE ÁOK-KA-2013/23 grant are gratefully appreciated. Data. S1. Material and methods. Fig. S1. Genome map of the Erwinia amylovora phage PhiEaH1. “
“Enterococci are among the most notorious bacteria involved in the spread of antibiotic resistance (ABR)

determinants via horizontal gene transfer, a process that leads to increased prevalence of antibiotic-resistant buy 17-AAG bacteria. In complex microbial communities with a high background of ABR genes, detection of gene transfer is possible only when the ABR determinant is marked. Therefore, the conjugative multiresistance plasmid pRE25, originating from a sausage-associated Enterococcus faecalis, was tagged with a 34-bp random sequence marker spliced by tet(M). The plasmid constructed, designated pRE25*, was introduced into E. faecalis CG110/gfp, a strain containing a gfp gene as chromosomal marker. The plasmid pRE25* is fully functional compared with its parental pRE25, occurs at one to two

copies per chromosome, and can be transferred to Listeria monocytogenes and Listeria innocua at frequencies of 6 × 10−6 to 8 × 10−8 transconjugants per donor. The markers on the chromosome and the plasmid enable independent quantification of donor and plasmid, even if ABR genes occur at high numbers in the background ecosystem. Both markers were stable for at least 200 generations, PS-341 supplier permitting application of the strain in long-running experiments. Enterococcus faecalis CG110/gfp/pRE25* is a potent tool for the investigation of horizontal ABR gene transfer in complex environments such as food matrices, biofilms or colonic models. Horizontal transfer of resistance genes and antibiotic-mediated selection pressure leads to a persistence and propagation of antibiotic-resistant bacteria in clinical environments, stock breeding, or in soil (Murray, 1990; Doucet-Populaire et al., 1991; Showsh & Andrews, 1992;

Agerso & Sandvang, 2005; Kazimierczak & Methocarbamol Scott, 2007). Transfer of antibiotic resistance (ABR) determinants can cross the genus barrier and is mainly mediated by conjugative elements such as transposons and plasmids (Shoemaker et al., 2001). Enterococci are Gram-positive, catalase-negative, oxidase-negative members of the functional related group of lactic acid bacteria predominantly encountered in the gastrointestinal tract (GI-tract) of humans and animals. Enterococci harbor a variety of mobile genetic elements such as conjugative plasmids and transposons and therefore the genus Enterococcus is supposed to be a main actor in the spreading of ABR genes (Clewell, 1990). Characterization of the human microbial community has revealed a vast diversity of resistance genes, indicating that the human microbial community acts as a reservoir of ABR genes (Shoemaker et al., 2001; Sommer et al., 2009).