title: Nanoscale structural and mechanical properties of nontypeable Haemophilus influenzae biofilms.
abstract: Nontypeable Haemophilus influenzae (NTHI) bacteria are commensals in the human nasopharynx, as well as pathogens associated with a spectrum of acute and chronic infections. Two important factors that influence NTHI pathogenicity are their ability to adhere to human tissue and their ability to form biofilms. Extracellular polymeric substances (EPS) and bacterial appendages such as pili critically influence cell adhesion and intercellular cohesion during biofilm formation. Structural components in the outer cell membrane, such as lipopolysaccharides, also play a fundamental role in infection of the host organism. In spite of their importance, these pathogenic factors are not yet well characterized at the nanoscale. Here, atomic force microscopy (AFM) was used in aqueous environments to visualize structural details, including probable Hif-type pili, of live NTHI bacteria at the early stages of biofilm formation. Using single-molecule AFM-based spectroscopy, the molecular elasticities of lipooligosaccharides present on NTHI cell surfaces were analyzed and compared between two strains (PittEE and PittGG) with very different pathogenicity profiles. Furthermore, the stiffness of single cells of both strains was measured and subsequently their turgor pressure was estimated.
authors.affiliation: Center for Nanomedicine, Department of Medicine (Pulmonary and Critical Care Section), University of Chicago, 5841 S Maryland Ave., I-505, Chicago, IL 60637, USA. ftarce@uchicago.edu
authors.forename: Fernando Terán
authors.initials: FT
authors.lastname: Arce
authors.forename: Ross
authors.initials: R
authors.lastname: Carlson
authors.forename: James
authors.initials: J
authors.lastname: Monds
authors.forename: Richard
authors.initials: R
authors.lastname: Veeh
authors.forename: Fen Z
authors.initials: FZ
authors.lastname: Hu
authors.forename: Philip S
authors.initials: PS
authors.lastname: Stewart
authors.forename: Ratnesh
authors.initials: R
authors.lastname: Lal
authors.forename: Garth D
authors.initials: GD
authors.lastname: Ehrlich
authors.forename: Recep
authors.initials: R
authors.lastname: Avci
mesh_terms: D018441:Biofilms; D004548:Elasticity; D010861:Fimbriae, Bacterial / Q000648:ultrastructure; D006193:Haemophilus influenzae / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D008070:Lipopolysaccharides / Q000737:chemistry; D018625:Microscopy, Atomic Force
chemical_list: D008070:Lipopolysaccharides