title: A spider web strategy of type IV pili-mediated migration to build a fibre-like Psl polysaccharide matrix in Pseudomonas aeruginosa biofilms.
abstract: Bacterial motilities participate in biofilm development. However, it is unknown how/if bacterial motility affects formation of the biofilm matrix. Psl polysaccharide is a key biofilm matrix component of Pseudomonas aeruginosa. Here we report that type IV pili (T4P)-mediated bacterial migration leads to the formation of a fibre-like Psl matrix. Deletion of T4P in wild type and flagella-deficient strains results in loss of the Psl-fibres and reduction of biofilm biomass in flow cell biofilms as well as pellicles at air-liquid interface. Bacteria lacking T4P-driven twitching motility including those that still express surface T4P are unable to form the Psl-fibres. Formation of a Psl-fibre matrix is critical for efficient biofilm formation, yet does not require flagella and polysaccharide Pel or alginate. The Psl-fibres are likely formed by Psl released from bacteria during T4P-mediated migration, a strategy similar to spider web formation. Starvation can couple Psl release and T4P-driven twitching motility. Furthermore, a radial-pattern Psl-fibre matrix is present in the middle of biofilms, a nutrient-deprived region. These imply a plausible model for how bacteria respond to nutrient-limited local environment to build a polysaccharide-fibre matrix by T4P-dependent bacterial migration strategy. This strategy may have general significance for bacterial survival in natural and clinical settings.
authors: State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
authors: Shiwei
authors: S
authors: Wang
authors: Matthew R
authors: MR
authors: Parsek
authors: Daniel J
authors: DJ
authors: Wozniak
authors: Luyan Z
authors: LZ
authors: Ma
mesh_terms: D000464:Alginates / Q000378:metabolism; D000818:Animals; D018441:Biofilms / Q000254:growth & development*; D004783:Environmental Microbiology; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism; D005407:Flagella / Q000235:genetics / Q000378:metabolism; D020723:Glucuronic Acid / Q000378:metabolism; D006603:Hexuronic Acids / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000235:genetics / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017384:Sequence Deletion
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D011135:Polysaccharides, Bacterial; D020723:Glucuronic Acid