baumannii expression properties that augment the organism’s ability to transition from exponential to stationary phase, as opposed to strain-dependent characteristics. Moreover, characterizing conserved biological processes may, in turn, provide rationale for developing strategies PI3K inhibitor for the therapeutic intervention of A. baumannii infections. Accordingly, each strain was cultured in LB medium, aliquots were removed during each growth phase, and RNA

was isolated and subjected to microarray analysis. The results presented here are refined to only those changes in gene expression that are conserved across both strains; individual strain expression properties are provided in Supporting Information, Table S1. Results revealed that the gene expression profiles of exponential- and stationary-phase A. baumannii differ dramatically and these differences are relatively well conserved

across the two strains studied. A total of 502 ORFs were determined to exhibit at least a twofold increase (t-test; P ≤ 0.05) in expression during exponential as opposed to stationary phase of growth regardless of the strain studied. Most of these genes belonged to distinct clusters of orthologous functional groups that are related to aspects of cell growth (Fig. 1). For instance, genes associated with amino acid metabolism (n = 43), translation (n = 93), cell wall/envelope selleck screening library biogenesis (n = 43), nucleotide transport (n = 28), transcription (n = 22), and replication (n = 21) were upregulated during exponential as opposed to stationary phase growth. Conversely, the mRNA levels of 175 genes were upregulated during stationary as opposed to exponential phase

in both strains. Of these, the majority were associated with energy production and conversion (n = 23), lipid transport all and metabolism (n = 15), and post-translational modification (n = 11). As described below, a more elaborate analysis of the data indicated that several genes that are likely to contribute to the organism’s ability to cause disease were found to be differentially expressed in a growth phase-dependent manner. Acinetobacter baumannii possesses the ability to survive on common hospital surfaces for weeks at a time, due in part to its ability to tolerate desiccation and form biofilms, subsequently providing a means for the organism to persist in the environment and act as a source for bacterial transmission to susceptible patients (Wendt et al., 1997; Jawad et al., 1998; Espinal et al., 2012). Our microarray data provided potential insight with regard to the biological systems that may contribute to the organism’s ability to form biofilms. More specifically, two members of the trehalose metabolic pathway, trehalose-6-phosphate synthase (A1S_0803), and trehalose-6-phosphate phosphatase (A1S_0804) were among the most highly upregulated stationary phase genes.