Samples from a sewage plant Steinhof in Braunschweig, Germany were centrifuged for 5 min at 4100 × g (Biofuge Fresco, Heraeus). Ten ml of the supernatant was mixed with 5 ml of a P. aeruginosa overnight culture and incubated in 50 ml LB broth at room

temperature. After an incubation of 48 h, the cells were sedimented by centrifugation at 4100 × g (Biofuge fresco) for 10 min and the supernatant was transferred to a clean tube. To kill the remaining bacteria, several this website drops of chloroform were added to the supernatant and the emulsion was mixed for 30 s. To separate the phages, appropriate dilutions of the phage lysate were spotted onto bacterial lawns of top-agar plates. Top-agar Selleckchem CA3 plates were produced by adding approximately 5 × 108 cells/ml of P. aeruginosa from an overnight LB broth to 3.5 ml of LB top-agar CX-5461 nmr (0.75%). The inoculated top-agar was overlaid on an LB agar plate and allowed to solidify. After incubation at 37°C for 10 to 16 h, zones of lysis were monitored. Single plaques, derived from a single phage, were separated by stinging with a pipette tip into the plaque followed by resuspending the phages in SM buffer (100 mM NaCl, 8 mM MgSO4, 50 mM Tris-HCl, pH 7.5). Five consecutive

single plaque isolates were processed for a pure culture, which was verified by electron microscopy. The resulting phage lysate was concentrated for further analysis using polyethylenglycol and stored at 4°C. Electron microscopy The morphology of the phages was determined by negative staining with 2% uranyl acetate (pH 4.8) and transmission electron microscopy. Phages were allowed to absorb onto a thin carbon film, prepared on mica,

from a liquid sample for different time points, washed in TE buffer (10 mM TRIS, 2 mM EDTA, pH 6.9) and distilled water. Phages were oxyclozanide negatively stained by floating the carbon film for appr. 15 sec on a drop of 2% aqueous uranyl acetate. Then, the carbon film was picked up with copper grids (300 mesh), blotted semi-dry with filter paper (Macherey-Nagel, MN615, 90 mm, Düren, Germany) and subsequently air dried. Samples were examined in a Zeiss EM910 transmission electron microsope at an acceleration voltage of 80 kV and calibrated using 30 nm gold particles at a magnification of 63.000. Images were recorded digitally with a Slow-Scan CCD-Camera (ProScan, 1024 × 1024, Scheuring, Germany) with ITEM-Software (Olympus Soft Imaging Solutions, Münster, Germany). Brightness and contrast were adjusted with Adobe Photoshop CS3. Determination of host range of phage JG004 To determine the phage host range, top-agar plates with the potential host lawn were prepared. Top-agar plates were produced by adding approximately 5 × 108 cells/ml of P. aeruginosa from an overnight LB broth to 3.5 ml of LB top agar (0.75%). Ten μl of a phage stock solution were spotted on the top-agar plate and incubated at 37°C for 12 to 16 h.