Figure 3

Mutant Laden Interfaces. Panels (A & B): Pendant drop elastometry, exponent, n (solid circles), and root mean square displacement d (open circles), vs. interface age for PAO1ΔflgK, PAO1ΔpelA, and PAO1ΔpilC laden interfaces. The line at n = 10⁰ indicates purely diffusive behavior; n < 10⁻¹ indicates an essentially solid elastic film. The PAO1ΔflgK laden interface transforms from diffusive to elastic layers, while colloids at interfaces in contact with the other mutants (PAO1ΔpilC, and PAO1ΔpelA) remain superdiffusive and or diffusive indicating that they retain some fluid character over the course of the experiment. All PAO1 knockouts develop skins on pendant drops, evidenced by wrinkles upon compression. Insets to Panel (B): Typical trajectories traced by a colloidal probe over 3 s at bacteria laden interfaces at early (~10² seconds) and late (~8 × 10⁴ seconds) interface ages. Scale bars, 1 micron, are the same for all trajectories. Panels (C & D): Pendant drop elastometry, exponent, n, and d, vs. interface age for PA14ΔflgK, PA14ΔpelA, and PA14ΔpilC laden interfaces; the PA14ΔpilC alone shows evidence of shear stress supporting film formation on the pendant drop; however, interfaces in contact with these mutants remain superdiffusive or diffusive through very late interface ages. Insets to panel (D): Typical trajectories traced by a colloidal probe over 3 s at bacteria laden interfaces at early (~10² seconds) and late (~8 × 10⁴ seconds) interface ages. Scale bars, 1 micron, are the same for all trajectories.