Obstacle of Surface-Deposited Microparticles to Bacterial Motility and Adhesion

Microparticles abundant in marine and aquatic environments can readily deposit on surfaces and influence the biofouling development there. So far, the impacts of micrometer scale particles on bacterial adhesion, including most sediments and cellular debris, remain unclear. By using digital holographic microscopy for real-time 3D bacterial tracking, we have investigated the interaction of Pseudomonas aeruginosa (PAO1) near surface deposited with particles having diameter of 0.5 to 8.0 μm sparsely distributed on the glass substrate. It reveals that the bacterial adhesion is reduced for all the particle-decorated surfaces compared with flat surface and shows size dependence with minimum adhesion on surfaces deposited with 5.0 μm particle. In addition, the near-surface motions of PAO1 are greatly changed by the microparticles. PAO1 speeds up with more continuous climbing and leveling as it approaches the particle. Flow simulation demonstrates that a deposited particle alters the local flow depending on its size, where a 5.0 μm particle has the shortest-range flow disruption. Anyhow, the hydrodynamic interaction between particles and bacteria is responsible for the near-surface bacterial motions. The present study provides a basis for designing marine antifouling materials.