Study Of Surface Motility On Surfaces With Different Physicochemical Properties Of Pseudomonas Aeruginosa

Biofilms of Pseudomonas aeruginosa are ubiquitously found on surfaces of many medical devices,which are the major cause of hospital-acquired infections.A large amount of work has been focused on bacterial attachment on surfaces.However,how bacterial cells evolve on surfaces after their attachment is the key to get a better understanding and control of biofilm formation.In this work,we study bacterial surface motilities on substrate surfaces with different physiochemical properties.Using a parallel high-throughput bacterial tracking technique,we develop a method to fully characterize bacterial surface motilities at a single-cell resolution by combining multiple quantitative parameters for both single-cell motility and collective motility of cells.As a result,bacteria move fast in a wider region on PVC with a higher possibility of walking and the trajectories are usually long and zigzag,while there are opposite phenomena observed on platinum.Inexplicably,bacterial speed on gold is smaller than on PC,while bacterial diffusion on PC and gold is similar.Thus the measurements of single-cell motility don't conform to a uniform relation on tested surfaces.But the measurements of collective surface motility show the surface exploration efficiencies are as follow:PVC>PC>glass>gold>platinum at N_s¹00,000,and the capacities of microcolony forming are as follow:PVC<glass<PC<gold<platinum,which show consistent results that gold and especially platinum surfaces have a higher capability in microcolony formation than PVC and PC surfaces,suggesting that metal surfaces may have a higher tendency to be contaminated by bacteria than plastic surfaces.Additionally,bacterial flagellum,type IV pili?TFP?and exopolysaccharides?Psl?have been shown to be important for bacterial attachment.We found that without TFP,bacteria only remain where they are,and cannot crawl across surface.So TFP is necessary for surface motility.Flagellum play a major role in the first adhesion interaction between cell and surface,and make a longer residence time on surface.Psl could greatly promote cell-surface adhesion and biofilm forming.But excess Psl expressed by?P_psl/P_BAD-psl also inhibit cell motility,resulting in aggregation in a certain local point.The results provide insights into how Pseudomonas aeruginosa adopt their motion to surfaces with different physicochemical properties,and would be beneficial for developing new anti-biofouling techniques in biomedical engineering.