Dynamic remodeling of microbial biofilms by functionally distinct exopolysaccharides.
Bottom Line: Conversely, Pel reduced effective cross-linking within the matrix.The wild-type biofilm decreased in effective cross-linking over time, which would be advantageous for the spreading and colonization of new surfaces.The exopolysaccharides were also found to have profound effects on the spatial organization and integration of P. aeruginosa in a mixed-species biofilm model of P. aeruginosa-Staphylococcus aureus.
Affiliation: BioSystems and Micromechanics IRG, Singapore-MIT Alliance for Research and Technology, National University of Singapore, Singapore.Show MeSH
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Mentions: We therefore suggest a new model for P. aeruginosa biofilm remodeling in which Psl is more elastic and acts as stiff wire-like structures to build the initial biofilm architecture and support on-site growth—e.g., the enlargement of existing microcolonies. Pel is more viscous and acts to allow spreading of cells in the matrix, which would be important for expansion during the later stages (Fig. 8). This complements previous studies that have shown that Psl is important for cell attachment (22), biofilm initiation, and microcolony development (20, 40), and Pel is important for pellicle formation (non-surface-attached or floating biofilm morphology) (19). The model presented here is based upon the early creep experiments conducted on P. aeruginosa streamers (8) and suggests that Psl is responsible for constructing the firmly surface-attached streamer head, while Pel designs the loose streamer tail. Recently, a combined optical and atomic force microscopy study has revealed that Psl expression results in cells tilting upwards off the surface, while Pel expression results in P. aeruginosa cells lying flat on surfaces (41). If cell orientation impacts the growth pattern, Psl would direct cells and growth upwards, increasing microcolony height, and Pel would direct cells to grow laterally for the spreading onto new surfaces, consistent with our model.
Affiliation: BioSystems and Micromechanics IRG, Singapore-MIT Alliance for Research and Technology, National University of Singapore, Singapore.