Poster: Eurobiofilms 2011, Kopenhagen, 06.07.-08.07.2011

Titel: Sodium hypochlorite stimulates biofilm formation in Pseudomonas aeruginosa

Autoren: Nikola Strempel, Jörg Overhage

Zusammenfassung: Pseudomonas aeruginosa is a ubiquitous motile Gram-negative bacterium that plays an important role as an opportunistic pathogen in infectious diseases. This bacterium is able to adapt to various environments due to the size and complexity of its genome as well as the sophisticated and coordinated regulation of gene expression mediated by a large number of regulatory elements. Recently, it has been shown that P. aeruginosa forms resistant biofilms in order to survive stressful environmental conditions e.g. growth in the presence of antimicrobial agents such as antibiotics or biocides. To investigate the stress response of P. aeruginosa PAO1 to sodium hypochlorite, a disinfectant which is commonly used in hospitals and drinking water treatment, we analyzed bacterial growth and biofilm formation in the presence of free chlorine at different concentrations. In static attachment and biofilm assays, free chlorine at subinhibitory concentrations of 2 µg/ml (w/v) led to a two-fold increase in early biofilm formation after two hours of incubation compared to the non-treated controls. The altered biofilm structure and composition caused by sodium hypochlorite treatment was further studied by fluorescence microscopy under static conditions as well as in continuous flow cell experiments. To identify the underlying mechanisms including regulatory genes involved in this enhanced biofilm forming response to sublethal concentrations of chlorine, microarray analyses and mutant screening were performed.