Associating Growth-Phase-Related Changes in the Proteome of Acinetobacter baumannii with Increased Resistance to Oxidative Stress

Acinetobacter baumannii is an opportunistic pathogen that has been associated with severe infections and outbreaks in hospitals. At present, very little is known about the biology of this bacterium, particularly as regards mechanisms of adaptation, persistence and virulence. To investigate the growth phase-dependent regulation of proteins in this microorganism, we analyzed the proteomic pattern of A. baumannii ATCC 17978 at different stages of in vitro growth. In this study, proteomics analyses were conducted using 2-DE and MALDI-TOF/TOF complemented by iTRAQ LC-MS/MS. Here we have identified 107 differentially expressed proteins. We highlight the induction of proteins associated with signaling, putative virulence factors and response to stress (including oxidative stress). We also present evidence that ROS (O2− and OH−) and RNI (ONOO−) accumulate during late stages of growth. Further assays demonstrated that stationary cells survive at high concentrations of H2O2 (30 mM), the O2− donor menadione (500 μM)...