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: To further explore the ecological impact of the rheological differences caused by Pel and Psl of P. aeruginosa, species integration within a dual-species biofilm comprised of P. aeruginosa and Staphylococcus aureus was investigated. Alg+ Pel+ Psl+P. aeruginosa cells and S. aureus formed biofilms comprised of two distinct layers. In the lower layer, P. aeruginosa and S. aureus were integrated into mixed-species microcolonies. In the upper layer, P. aeruginosa dominated the biofilm, forming monospecies biofilms that capped the microcolonies (Fig. 7A). Alg+ Pel− Psl+P. aeruginosa cells did not associate with S. aureus and formed separate microcolonies at the substratum. P. aeruginosa also dominated the upper part of the biofilm, forming a monospecies biofilm layer on top of the microcolonies from both species (Fig. 7B). Alg+ Pel+ Psl−P. aeruginosa cells associated with S. aureus to form a mixed-species biofilm with a less prominent monospecies P. aeruginosa cap (Fig. 7C). Alg+ Pel− Psl−P. aeruginosa cells were unable to associate with S. aureus and could only form small clusters of monospecies P. aeruginosa cells. The amount of S. aureus biofilm was minimal when grown in the presence of Alg+ Pel− Psl−P. aeruginosa (Fig. 7D). Thus, Pel was required for integration of P. aeruginosa into mixed-species biofilms, while Psl promoted species segregation and monospecies biofilms. P. aeruginosa outcompeted S. aureus without the two polysaccharides.
Affiliation: BioSystems and Micromechanics IRG, Singapore-MIT Alliance for Research and Technology, National University of Singapore, Singapore.