Genetic basis of phenotypic tolerance in Pseudomonas aeruginosa.

Pseudomonas aeruginosa is a ubiquitous Gram-negative bacterium and also an important nosocomial pathogen and the major pathogen chronically colonizing the lungs of cystic fibrosis patients. It is known for its high resistance to many antibiotics and for its capacity of adaptation to stress conditions. The aim of the FWO project was to get a better insight into the mechanisms of persistence of P. aeruginosa after antibiotic treatment as well as into the mechanisms involved in resistance to different stresses. The FWO project G.0299.07 project is a collaborative project coordinated by prof. Jan Michiels (CMPG/KULeuven) and our group. The KULeuven group studies the physiology and the genes involved in the persister phenotype. SCVs are slow growing phentypic variants that typically are more resistant to antibiotics and can revert to wild-type phenotype. We are investigating such a gentamycin-resistant SCV from P. aeruginosa (PhD of Q. Wei). In both cases profound phenotypic changes were observed including defective iron uptake and plating efficiency for the oxyR mutant as well as other phenotypic changes suggesting a disruption of quorum sensing (Vinckx et al., 2008), and absence of the production of the PQS quorum sensing molecule in the SCV mutant this research combines physiological characterization, transcriptomic, a,d proteomic analysis and is ongoing. We expect to submit two other publications based on these results in a near future.