Antibiofilm activity of species from the cystic fibrosis lung microbiota against .

It is increasingly recognized that interspecies interactions may modulate the pathogenicity of during chronic lung infections. Nevertheless, while the interaction between and pathogenic microorganisms co-infecting the lungs has been widely investigated, little is known about the influence of other members of the lung microbiota on the infection process. In this study, we focused on investigating the impact of species isolated from the sputum of people with cystic fibrosis (pwCF) on biofilm formation and virulence factor production by . Screening of a representative collection of species recovered from clinical samples showed that several members of this genus (8 out 10 isolates) were able to significantly reduce biofilm formation of PAO1, without impact on growth. Among the tested isolates, the strongest biofilm-inhibitory activity was observed for and , which caused a reduction of up to 90% in the total biofilm biomass of several isolates from pwCF. In addition, a strain-specific effect of on the ability of to produce proteases and pyocyanin was observed, with significant alterations in the levels of these virulence factors detected in LasR mutant strains. Overall, these results suggest that non-pathogenic bacteria from the lung microbiota may regulate pathogenicity traits of , and possibly affect the outcome of chronic lung infections.