(461e) Bacterial Locomotion at Evolving Oil-Water Interface Prior to Elastic Film Formation

We study the motion of Pseudomonas aeruginosa at the interface between oil and bacterial suspensions. While the behavior of microbes during the formation of biofilms on solid surfaces is well studied, the behavior of bacteria during formation of films at fluid interfaces is not known. Film formation is thought toinitiate with bacteria adhesion in both cases. Here, we focus on the motion of Pseudomonas aeruginosa PAO1and PA14 at early stage of the film formation. The velocity, reorientation, and dispersion coefficient of thebacterial cells trapped on the interface are studied over time. Furthermore, the concentration profiles ofbacterial suspensions below the interface are measured. Pseudomonas aeruginosa PA14DpelA, which does not restructure the interface, is chosen as the control strain. Pseudomonas aeruginosa PA01, however, secretes polysaccharides and surfactants and consequently evolves the microscopic mechanics of the interface. We study the effect of these rheological changes on the locomotion of the bacteria and investigate the effect of the interfacial viscosity and viscoelasticity on the bacterial trajectories.