Flagella but not type IV pili are involved in the initial adhesion of Pseudomonas aeruginosa PAO1 to hydrophobic or superhydrophobic surfaces.

Over the last decades, surface biocontamination has become a major concern in food industries and medical environments where its outcomes could vary from financial losses to public health issues. Understanding adhesion mechanisms of involved microorganisms is essential to develop new strategies of prevention and control. Adhesion of Pseudomonas aeruginosa, a nosocomial pathogenic bacterium, relies on several bacterial features, among which are bacterial appendages such as flagella and type IV pili. Here, we examine the role of P. aeruginosa PAO1 flagella and type IV pili in the adhesion to abiotic surfaces with various hydrophobicities. Adhesion kinetics showed, that after 60min, flagella increased the adhesion of the strain to surfaces with high hydrophobicity while no effect was observed on hydrophilic surfaces. Flagella of adherent bacteria exhibited specific and conserved pattern on the surfaces that suggested a higher affinity of flagella for hydrophobic surfaces. Based on these results and on previous studies in the literature, we proposed a model of flagella-mediated adhesion onto hydrophobic surfaces where these appendages induce the first contact and promote the adhesion of the bacterial body. These findings suggest that anti-bioadhesive surface design should take into consideration the presence of bacterial appendages.