salmonis. Piscirickettsia salmonis strain LF-89 (ATCC VR-1361) was maintained routinely on BCG agar plates (10 g L−1 tryptone, 5 g L−1 peptone, 5 g L−1 yeast extract, 5 g L−1 NaCl, 10 g L−1 glucose, 5% sheep blood and 1%l-cysteine) at 23 °C (modified from Mauel et al.,

2008). CDK inhibitor A single bacterial colony was used to inoculate 25 mL of MC5 medium, and the inoculated medium was incubated at 23 °C and 100 r.p.m. of agitation. The composition of the MC5 culture medium will be published shortly (patent pending). Three isolates of P. salmonis collected from Atlantic salmon (Salmo salar) during 2010 from different epizootics in Puerto Montt (Chile) were maintained on the CHSE-214 cell line (ATCC CRL-1681) as been described previously (Rojas et al., 2009). Monolayers

of CHSE-214 cells were routinely propagated at 17 °C in 25 cm2 culture flasks containing minimal essential medium (MEM; Gibco), supplemented with 7.5% heat-inactivated fetal bovine serum and adjusted to pH 7.2 with 10 mM sodium bicarbonate and 15 mM HEPES. Two-day-old P. salmonis LF-89 liquid cultures were centrifuged at 6000 g for 20 min, and genomic DNA was extracted using the AxyPrep™ Multisource Genomic DNA Miniprep Kit (AxyGen Bioscience) according to the manufacturer’s instructions. To obtain DNA from the three isolates of P. salmonis, this website 1 mL of 15-day-old supernatants from CHSE-214 infected cell line was centrifuged at 20 000 g for 15 min. The DNA from the resultant pellets was extracted using the Chelex-100 resin (BioRad) as described previously (Walsh et al., 1991). The DNA

Phosphoribosylglycinamide formyltransferase concentration from all samples was determined by spectrophotometry using a Nanodrop-1000 and the DNA was kept at −20 °C until use. A genomic DNA library of P. salmonis was constructed in the plasmid pBluescript SK (+) (Fermentas). Bacterial genomic DNA (3 μg) was partially digested with Sau3AI (New England Biolabs) for 30 min at 37 °C. The digestion reaction was stopped at 65 °C for 10 min. Following phenol : chloroform extraction and ethanol precipitation, the DNA was resuspended in 15 μL of nuclease-free water (IDT DNA Technologies). The pBluescript SK (+) vector was completely digested with the BamHI restriction enzyme (New England Biolabs) for 12 h at 37 °C and treated for 1 h with alkaline phosphatase (Promega) according to the protocol supplied by the manufacturer. Both digested DNAs were visualized by 1% agarose gel electrophoresis and stained with GelRed™ (Biotium). Finally, 600 ng of digested bacterial DNA and 300 ng of linearized pBluescript SK (+) vector DNA were ligated with T4 DNA ligase (Promega). The ligation mixture was used to transform Escherichia coli TOP10 cells by electroporation. The selection of transformants was performed on Luria–Bertani (LB) agar containing 50 μg mL of kanamycin (Sigma-Aldrich) in the presence of X-Gal (Promega).