title: High-resolution topography of the S-layer sheath of the archaebacterium Methanospirillum hungatei provided by scanning tunneling microscopy.
abstract: The inner and outer surfaces of the sheath of Methanospirillum hungatei GP1 have been imaged for the first time by using a bimorph scanning tunneling microscope (STM) on platinum-coated or uncoated specimens to a nominal resolution in height of ca. 0.4. nm. Unlike more usual types of microscopy (e.g., transmission electron microscopy), STM provided high-resolution topography of the surfaces, giving good depth detail which confirmed the sheath to be a paracrystalline structure possessing minute pores and therefore impervious to solutes possessing a hydrated radius of greater than 0.3 nm. STM also confirmed that the sheath consisted of a series of stacked hoops approximately 2.5 nm wide which were the remnants of the sheath after treatment with 2% (wt/vol) sodium dodecyl sulfate-2% (vol/vol) beta-mercaptoethanol (pH 9.0). No topographical infrastructure could be seen on the sides of the hoops. This research required the development of a new long-range STM capable of detecting small particles such as bacteria on graphite surfaces as well as a new "hopping" STM mode which did not deform the poorly conducting bacterial surface during high-resolution topographical analysis.
authors.affiliation: Department of Microbiology, College of Biological Science, University of Guelph, Ontario, Canada.
authors.forename: T J
authors.initials: TJ
authors.lastname: Beveridge
authors.forename: G
authors.initials: G
authors.lastname: Southam
authors.forename: M H
authors.initials: MH
authors.lastname: Jericho
authors.forename: B L
authors.initials: BL
authors.lastname: Blackford
mesh_terms: D001105:Archaea / Q000648:ultrastructure*; D002462:Cell Membrane / Q000648:ultrastructure; D008854:Microscopy, Electron; D016252:Microscopy, Scanning Tunneling / Q000379:methods; D010984:Platinum
chemical_list: D010984:Platinum