title: Microbial polysaccharides template assembly of nanocrystal fibers.
abstract: Biological systems can produce extraordinary inorganic structures and morphologies. The mechanisms of synthesis are poorly understood but are of great interest for engineering novel materials. We use spectromicroscopy to show that microbially generated submicrometer-diameter iron oxyhydroxide (FeOOH) filaments contain polysaccharides, providing an explanation for the formation of akaganeite pseudo-single crystals with aspect ratios of approximately 1000:1. We infer that the cells extrude the polysaccharide strands to localize FeOOH precipitation in proximity to the cell membrane to harness the proton gradient for energy generation. Characterization of organic compounds with high spatial resolution, correlated with mineralogical information, should improve our understanding of biomineralization mechanisms.
authors.affiliation: Department of Earth and Planetary Science, University of California, Berkeley, CA 94720, USA.
authors.forename: Clara S
authors.initials: CS
authors.lastname: Chan
authors.forename: Gelsomina
authors.initials: G
authors.lastname: De Stasio
authors.forename: Susan A
authors.initials: SA
authors.lastname: Welch
authors.forename: Marco
authors.initials: M
authors.lastname: Girasole
authors.forename: Bradley H
authors.initials: BH
authors.lastname: Frazer
authors.forename: Maria V
authors.initials: MV
authors.lastname: Nesterova
authors.forename: Sirine
authors.initials: S
authors.lastname: Fakra
authors.forename: Jillian F
authors.initials: JF
authors.lastname: Banfield
mesh_terms: D001419:Bacteria / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D018441:Biofilms; D002462:Cell Membrane / Q000378:metabolism; D003460:Crystallization; D005290:Ferric Compounds / Q000737:chemistry*; D005293:Ferritins / Q000737:chemistry* / Q000378:metabolism; D005296:Ferrous Compounds / Q000737:chemistry / Q000378:metabolism; D043372:Gallionellaceae / Q000648:ultrastructure; D019015:Geologic Sediments / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D042743:Leptothrix / Q000648:ultrastructure; D008854:Microscopy, Electron; D008906:Mining; D010084:Oxidation-Reduction; D011108:Polymers; D011135:Polysaccharides, Bacterial / Q000737:chemistry* / Q000378:metabolism*; D018892:Proton-Motive Force; D013052:Spectrometry, X-Ray Emission; D014871:Water Microbiology
chemical_list: D005290:Ferric Compounds; D005296:Ferrous Compounds; D011108:Polymers; D011135:Polysaccharides, Bacterial; C473845:akaganeite; C092844:ferric oxyhydroxide; D005293:Ferritins