title: Quantitative analysis of amyloid-integrated biofilms formed by uropathogenic Escherichia coli at the air-liquid interface.
abstract: Bacterial biofilms are complex multicellular assemblies, characterized by a heterogeneous extracellular polymeric matrix, that have emerged as hallmarks of persistent infectious diseases. New approaches and quantitative data are needed to elucidate the composition and architecture of biofilms, and such data need to be correlated with mechanical and physicochemical properties that relate to function. We performed a panel of interfacial rheological measurements during biofilm formation at the air-liquid interface by the Escherichia coli strain UTI89, which is noted for its importance in studies of urinary tract infection and for its assembly of functional amyloid fibers termed curli. Brewster-angle microscopy and measurements of the surface elasticity (G(s)') and stress-strain response provided sensitive and quantitative parameters that revealed distinct stages during bacterial colonization, aggregation, and eventual formation of a pellicle at the air-liquid interface. Pellicles that formed under conditions that upregulate curli production exhibited an increase in strength and viscoelastic properties as well as a greater ability to recover from stress-strain perturbation. The results suggest that curli, as hydrophobic extracellular amyloid fibers, enhance the strength, viscoelasticity, and resistance to strain of E. coli biofilms formed at the air-liquid interface.
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Wu
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California.
authors.forename: Ji Youn
authors.initials: JY
authors.lastname: Lim
authors.affiliation: Department of Chemical Engineering, Stanford University, Stanford, California.
authors.forename: Gerald G
authors.initials: GG
authors.lastname: Fuller
authors.affiliation: Department of Chemistry, Stanford University, Stanford, California. Electronic address: cegelski@stanford.edu.
authors.forename: Lynette
authors.initials: L
authors.lastname: Cegelski
mesh_terms: D000388:Air; D000682:Amyloid / Q000378:metabolism*; D018441:Biofilms; D055119:Elastic Modulus; D008854:Microscopy, Electron; D012212:Rheology; D013314:Stress, Mechanical; D013499:Surface Properties; D056689:Uropathogenic Escherichia coli / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure
chemical_list: D000682:Amyloid