Morphological and structural aspects of the extremely halophilic archaeon Haloquadratum walsbyi

• Published in: PloS one Vol. 6; no. 4; p. e18653
• Main Authors: Sublimi Saponetti, Matilde, Bobba, Fabrizio, Salerno, Grazia, Scarfato, Alessandro, Corcelli, Angela, Cucolo, Annamaria
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 29.04.2011; Public Library of Science (PLoS)
• Subjects: Animals; Archaea; Archaea - physiology; Atomic force microscopy; Biochemistry; Biology; Cell Shape; Cell surface; Coastal waters; Drying; Evolution, Molecular; Genomes; Giant protein; Halobacteriaceae - genetics; Halobacteriaceae - physiology; Haloquadratum walsbyi; Lakes; Microorganisms; Microscopes; Microscopy; Microscopy, Atomic Force - methods; Microscopy, Fluorescence - methods; Microscopy, Phase-Contrast - methods; Morphology; Mucins - chemistry; Mucins - physiology; Oscillometry - methods; Periodic variations; Periodicity; Phylogeny; Physics; Physiological aspects; Physiology; Proteins; Reproducibility of Results; Salt lakes; Salterns; Salts; Skewed distributions; Sodium Chloride - chemistry; Studies; Surface boundary layer; Water Microbiology
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0018653

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.