Enterococcus faecalis OG1RF control vs. treatment with vancomycin

Transcriptional profiling to investigate the effect of drug treatment on the E. faecalis cells. For microarray analysis, E. faecalis OG1RF was grown in FMC medium supplemented with 10 mM glucose to an optical density at 600 nm (OD600) of 0.3 and the cultures were divided in 3 aliquots. One aliquot was collected by centrifugation and immediately frozen (untreated control cells). The other aliquots were treated for 30 or 60 min with 1.25 X the minimum inhibitory concentration (MIC) of vancomycin (10 μg ml-1). After an exposure time of 30 or 60 minutes, each of these cultures was also centrifuged and the pellets frozen. RNA was then isolated from each pellet for microarray analysis. This process was repeated 3 additional times, for a total of four replicates of each condition. RNA was extracted from four replicate samples of each condition of interest (control cells grown to OD600 = 0.3 in FMC medium supplemented with 10mM glucose, then treated with vancomycin for 30 or 60 minutes) and labeled with Cy3. For each replicate, labeled RNA was hybridized to slides along with Cy5-labeled reference RNA, extracted from E. faecalis OG1RF cells grown in BHI medium to mid-log.