(620f) Sticking and Slipping of Active Bacteria on Silanized Glass Surfaces

Bacterial biofilms foul a wide range of engineered surfaces, from pipelines to membranes to biomedical implants, and lead to deleterious costs for industry and for human health. Designing strategies to reduce bacterial fouling requires fundamental understanding of mechanisms by which active and motile bacteria attach to surfaces. Here, we correlate the near-surface motion of Escherichia coli bacteria with transient adhesion and deposition onto silanized glass surfaces. We image bacteria as they flow through a linear channel and attach to the surface using confocal microscopy, and track their position and orientation over time using image processing algorithms. The deposition rate of bacteria on surfaces of varying silane chemistry and chain length does not correlate with surface energy or zeta potential. Instead, we find that a metric based on the degree of near-surface flagella-driven motion is inversely correlated with the rate at which bacteria deposit on these surfaces. On very smooth surfaces these bacteria exhibit mobile adhesion, in which surface-associated cells slip along the surface in the direction of flow, but this behavior cannot be described by colloidal models that predict detachment from hydrodynamic and/or adhesive interactions. We find that E. coli bacteria with and without flagella exhibit mobile adhesion, indicating that this behavior is not driven by these appendages, but cells that express fimbriae do not exhibit mobile adhesion. These experiments suggest that surface-associated motion enabled by surface appendages alters bacterial adhesion to surfaces in the earliest stages of biofilm formation.