Characterization of Interfacial Films of Mucoid and Nonmucoid Pseudomonas Aeruginosa Isolates.

Fluid interfaces are energy rich environments ideal for the self-assembly of micro/nano sized particles and film formation by biological entities. The formation of such films appears to be a dynamics process, in which cells respond to the entrapment and the existing interfacial energies by forming a film appropriate to their survival. We hypothesize that cells subjected to continuous interfacial stress adapt and evolve to exhibit phenotypic changes essential to their survival. In this study, we investigated the interfacial properties of films formed by non-mucoid (PANT) and mucoid (PASL) strains of P. aeruginosa isolated from CF (Cystic Fibrosis) patients. Under constant strain, PANT forms a conserved viscoelastic film exhibiting similar response under compression and tension whereas PASL exhibits more relaxation under compression than tension. Microscopic analysis revealed that interfacial films of PASL retained an intact cellular morphology compared to PANT, which include large number of lysed cells. This indicates that mucoid coating of PASL plays an important role in protecting the bacteria from interfacial stresses. Transcriptional profiling demonstrated that the gene expression under interfacial confinement is distinct to mucoid and non-mucoid cells suggesting that phenotypic differences in cells alter their behavior at fluid interfaces.