Next, the upper layer of the surface was scratched from the five slices, resuspended in 25 ml of PBS and centrifuged for 2 min at 4000 rpm. The supernatant was transferred to 15 ml killing buffer and further processed as described above. RNA isolation and quantitative real-time PCR Cell cultures were grown Stattic in vitro in LB broth until the desired optical densities were achieved. An aliquot containing

15 × 109 CFU (equivalent of 15 ml OD600 of 1.0) was transferred to 15 ml killing buffer and centrifuged for 20 min at 4000 rpm. The supernatant was decanted and the pellet frozen at -80°C for further RNA extraction. Total RNA was isolated by acid phenol/chloroform extraction [53]. The obtained RNA was treated with DNAse (Ambion/Life Technologies, Darmstadt, Germany) and subsequently checked for purity by gel electrophoresis and determination of the A260/A280 and A260/A230 ratios using a Nanodrop ND-2000 selleck compound spectrophotometer (Thermo Fischer Scientific). High quality RNA was reverse transcribed and amplified with the OneStep

RT-PCR Kit according to the manufacturer’s protocol (Qiagen, Hilden, Germany). Template RNA (5 ng) was used in a standard 25-μl qRT-PCR reaction with specific primers (see Additional file 6). As negative control, RNA samples without reverse transcriptase were included to detect possible DNA contaminations. For analysis, a Mastercycler ep realplex 2 gradient S (Eppendorf, Hamburg, Germany) was used. Cycling parameters included a 15 min initial denaturation at 95°C to activate the DNA polymerase followed by 40 cycles consisting of 15 sec at 95°C, 30 sec at 55°C and 30 sec at 72°C. The final step consisted of 1 min at 95°C and 30 sec at 55°C. A melting curve analysis with a temperature ramp from 25°C to 95°C in 20 min was performed at the end of each run to determine specificity of amplified qPCR products. Each sample was analyzed for gene expression in triplicate. Quantification of mRNA transcripts was performed by the comparative Ct method. Briefly, the Ct values of the samples of interest were compared with a non-treated sample. All Ct values

were normalized to the housekeeping gene recA, which shows constant expression at different ODs and medium compositions PRKACG as well as similar amplification efficiency to the target genes [55]. The comparative Ct Sapanisertib ic50 method was calculated by , where ΔCt was normalized to the endogenous housekeeping gene recA. Subsequently, fold-changes between the samples were determined based on the calculated Ct method. Expression of the BaeR protein Expression of BaeR was achieved by using the vector pBAD24 where the expression is controlled by the PBAD promoter and araC. Therefore, we cloned baeR under control of the arabinose inducible promoter (pBAD24.baeR) and transformed the plasmid into E. amylovora wild-type cells. Protein expression was induced by adding 1% L-arabinose when cultures reached an OD600 of 0.5.