Briefly, 8 mL of overnight culture was washed twice in phosphate-buffered saline and resuspended VE-821 concentration in 235 μL of Suspension Buffer with RNase A + 15 μL of lysostaphin (Dr. Petry Genmedics, Reutlingen, Germany) (0.5 mg mL−1). Then, it was left incubating at 37 °C

for 15 min. After the treatment, 250 μL of lysis buffer was added. The restriction endonuclease HindIII (Roche Diagnostics) was used to digest plasmid DNA according to the manufacturer’s protocol. The digested DNA was analyzed by electrophoresis in 1.8% agarose gel (Serva, Heidelberg, Germany) in 1× TAE buffer at 5 V cm−1. 2-Log DNA Ladder (New England Biolabs, Ipswich, MA) was used as DNA molecular weight marker. Ethidium bromide staining and UV irradiation were employed for DNA visualization.

The complete nucleotide sequence of the 3 kb cryptic plasmid present in strain 07/235 was determined by Sanger capillary sequencing. All sequencing steps were performed by Eurofins MWG Operon (Ebersberg, Germany). Plasmid-borne resistance genes were detected by PCR using primers for the β-lactamase gene blaZ (Martineau et al., 2000), tetracycline resistance gene tetK (Ng et al., 2001), and cadmium resistance gene cadD (primers cadD-F GGATATTAGGTTTATTGGGTT Z-VAD-FMK supplier and cadD-R CGCCACAACTTGCTATCGTA). Each reaction mixture (25 μL) contained 1× PCR buffer, 0.2 mM dNTP, 1.5 mM MgCl2, 0.2 mM of each primer, 1 U Taq DNA polymerase (Invitrogen Life Technologies, Carlsbad, CA), and 10 ng of template plasmid DNA. Initial denaturation of DNA

at 94 °C for 5 min was followed by 30 amplification cycles (94 °C for 30 s, 55 °C for 30 s, 72 °C for 45 s), ending with a final extension phase at 72 °C for 4 min. PCR products were separated by electrophoresis as was plasmid DNA. Bacteriophage integrase types and morphogenesis gene types corresponding to serological groups of prophages in the genomes of the strains were identified by multiplex PCR as described previously (Kahánková et al., 2010). The test for β-lactamase production was made using nitrocefin disk assay according to the manufacturer’s recommendations (Erba Lachema, Brno, Czech Republic). DNA from phage particles was isolated as described (-)-p-Bromotetramisole Oxalate previously (Doškař et al., 2000). RNase A (Serva) and DNase I (Sigma, St Louis, MO) were added to the samples to final concentration 1 and 5 μg mL−1, respectively, to remove contaminating exogenous bacterial DNA. qPCR experiments were performed on the Applied Biosystems 7300 Real-Time PCR System (Applied Biosystems, Foster City, CA). Each reaction mixture (25 μL) contained 12.5 μL 2× FastStart Universal SYBR® Green Master (Rox) (Roche Diagnostics), 900 nM of each primer, and 10 ng of template DNA. For the standard, the amount of template DNA ranged from 10 ng to 0.1 pg in 10-fold fashion.