3a). All four of these inhibitory compounds reduced the biomass by over 80% at the highest concentration (25 mM), with decanol, dodecanol and decanoic acid showing no significant differences between their concentration-dependent inhibitory profiles across the range tested. Biomass inhibition by octanoic acid was not observed until ≥1.6 mM. The three most effective exogenous inhibitory compounds were tested against preformed mature selleck chemical A. fumigatus biofilms. The biomass of A. fumigatus biofilms was shown to be reduced by all three compounds in a concentration-dependent manner, with decanol showing a reduction across the entire concentration range tested,

whereas both decanoic acid and dodecanol did not reduce the biomass significantly until concentrations of 1.6 mM were applied. All

three agents reduced the biomass by ≥85% at 25 mM (Fig. 3b). The pulmonary cavity of CF patients is a unique environment impacted by a complex microbial ecology. However, to date, relatively little is known about bacterial–fungal cross kingdom interactions within the CF lung. Cell-to-cell signalling is thought to play an important role in determining the ability of particular pathogens to compete with each other for space and nutrients and may contribute to the ability of microorganisms to persist within the CF pulmonary cavity. The data presented herein are suggestive that an antagonistic relationship exists between A. fumigatus and P. aeruginosa, which is influenced through the Mannose-binding protein-associated serine protease PS-341 nmr release of small diffusible extracellular molecules. Pseudomonas aeruginosa and A. fumigatus are frequently isolated from CF patients. Typically by the age of 18, up to 80% of CF patients are infected with P. aeruginosa, whereas the incidence of A. fumigatus is somewhat variable in CF patients (Bakare et al., 2003; Valenza et al., 2008). This study demonstrated that P. aeruginosa significantly impedes A. fumigatus growth. This is in agreement with reports from elsewhere describing antagonistic properties for bacteria isolated from clinical pulmonary samples (Kerr et al., 1999; Yadav et al., 2005). However,

investigation of the antifungal properties of bacterial CF lung pathogens against a panel of fungi, including A. fumigatus, showed that P. aeruginosa clinical isolates were shown to be unable to completely inhibit A. fumigatus (Kerr, 1994a, b). In agreement, our data showed that once filamentous biofilms had been produced, the inhibitory capacity of P. aeruginosa was significantly restricted, with coaggregation upon hyphae observed throughout A. fumigatus biofilms. Recent studies report a similar phenomenon, where P. aeruginosa and C. albicans were shown to exhibit a degree of mutual inhibition within the biofilm (Bandara et al., 2010b), suggesting that these mixed species consortia play a role in the pathobiology of the CF lung.