Proteomic approach to Pseudomonas aeruginosa adaptive resistance to benzalkonium chloride

This study aimed to assess the membrane modifications in Pseudomonas aeruginosa after continuous exposure to increasing doses of benzalkonium chloride (BC). Two different concentrations were used, 0.9 and 12.0 mM. Proteomic investigations revealed that the range of the outermembrane proteome alterations following continuous exposure is very low, i.e. about 10% and BC concentration dependent. Adapted cells revealed different expressions of key proteins frequently reported as involved in acquired resistance mechanisms. Porins (OprF and OprG) and lipoproteins (OprL and OprI) were underexpressed when the higher adaptation concentration (12 mM) was used. Some of thesemembrane alterations have been described as involved in the acquired resistance to antibiotics, suggesting possible commonmechanisms between these two types of resistance.The authors would like to acknowledge the financial support from IBB-CEB and Fundacao para a Ciencia e Tecnologia (FCT) and European Community fund FEDER, through Program COMPETE, in the ambit of the Project PTDC/SAUESA/64609/2006/FCOMP-01-0124-FEDER-00702 and Idalina Machado PhD Grant (SFRH/BD/31065/2006)