Paper BI+AS-MoM2
Bacterial Adhesion to Immobilized Liquid Layers under Dynamic Conditions

Monday, November 7, 2016, 8:40 am, Room 101A

Immobilized liquid (IL) layers are an emerging technology shown to prevent bacterial biofouling of surfaces. In this work, we show how in one class of IL-coated materials, infused polymers, bacterial adhesion can be strongly dependent on growth conditions. Samples grown with Escherichia coli under more relevant dynamic conditions showed significantly increased colony-forming unit counts compared to the same system grown under static conditions. Direct visualization of the surfaces suggested that this was due to a disturbance of the IL layer when exposed to shaking conditions, which allowed more bacteria to remain on the surface after an initial rinse. However, no incorporation of the bacteria into the oil layer was detected. To further investigate the extent of this adhesion, we used sequential removal cycles to gauge the relative adhesion strength of the remaining surface-bound E. coli. Through this method, we found that despite no initial difference in adherent CFUs compared to control samples with no IL layers, IL samples did reduce overall adhesion of the bacteria even after incubation under dynamic conditions. Further tests on a flagella-deficient strain of E. coli revealed that while flagella play a significant role in adhesion to IL layers, they are not the sole adhesion mechanism for this species. Finally, tests on two other clinically-relevant species of bacteria, Staphylococcus aureus and Pseudomonas aeruginosa, using similar methods revealed clear species-dependent differences in adhesion after growth under dynamic conditions. These results shed new light on the interaction of bacteria with IL layers, and demonstrate the importance of both relevant growth conditions and thorough analysis to obtaining clear results in these systems.