title: Morphological and structural aspects of the extremely halophilic archaeon Haloquadratum walsbyi.
abstract: Ultrathin square cell Haloquadratum walsbyi from the Archaea domain are the most abundant microorganisms in the hypersaline water of coastal salterns and continental salt lakes. In this work, we explore the cell surface of these microorganisms using amplitude-modulation atomic-force microscopy in nearly physiological conditions. We demonstrate the presence of a regular corrugation with a periodicity of 16-20 nm attributed to the surface layer (S-layer) protein lattice, striped domains asymmetrically distributed on the cell faces and peculiar bulges correlated with the presence of intracellular granules. Besides, subsequent images of cell evolution during the drying process indicate the presence of an external capsule that might correspond to the giant protein halomucin, predicted by the genome but never before observed by other microscopy studies.
authors.affiliation: Department of Physics and Research Centre NanoMateS, University of Salerno and SPIN-CNR, Fisciano, Italy. m.sublimi@sa.infn.it
authors.forename: Matilde
authors.initials: M
authors.lastname: Sublimi Saponetti
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Bobba
authors.forename: Grazia
authors.initials: G
authors.lastname: Salerno
authors.forename: Alessandro
authors.initials: A
authors.lastname: Scarfato
authors.forename: Angela
authors.initials: A
authors.lastname: Corcelli
authors.forename: Annamaria
authors.initials: A
authors.lastname: Cucolo
mesh_terms: D000818:Animals; D001105:Archaea / Q000502:physiology; D048430:Cell Shape; D019143:Evolution, Molecular; D006216:Halobacteriaceae / Q000235:genetics* / Q000502:physiology*; D018625:Microscopy, Atomic Force / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D008858:Microscopy, Phase-Contrast / Q000379:methods; D009077:Mucins / Q000737:chemistry / Q000502:physiology; D009991:Oscillometry / Q000379:methods; D010802:Phylogeny; D015203:Reproducibility of Results; D012965:Sodium Chloride / Q000737:chemistry; D014871:Water Microbiology
chemical_list: D009077:Mucins; D012965:Sodium Chloride