Volume 18, Issue 5 p. 606-618
ORIGINAL ARTICLE

Micro- and nano-scale mineralogical characterization of Fe(II)-oxidizing bacterial stalks

Ruggero Vigliaturo

Corresponding Author

Ruggero Vigliaturo

Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA, USA

Correspondence

Ruggero Vigliaturo, Department of Earth and Environmental Science, University of Pennsylvania, 240 S. 33rd Street, Philadelphia, PA 19104-6316, USA.

Email: ruggero.vigliaturo@gmail.com

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Alessandra Marengo

Alessandra Marengo

Department of Earth Science, University of Torino, Torino, Italy

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Erica Bittarello

Erica Bittarello

Department of Earth Science, University of Torino, Torino, Italy

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Ileana Pérez-Rodríguez

Ileana Pérez-Rodríguez

Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA, USA

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Goran Dražić

Goran Dražić

Department for Materials Chemistry, National Institute of Chemistry, Ljubljana, Slovenia

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Reto Gieré

Reto Gieré

Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, PA, USA

Center of Excellence in Environmental Toxicology, University of Pennsylvania, Philadelphia, PA, USA

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First published: 27 May 2020
Citations: 5

Abstract

Neutrophilic, microaerobic Fe(II)-oxidizing bacteria (FeOB) from marine and freshwater environments are known to generate twisted ribbon-like organo-mineral stalks. These structures, which are extracellularly precipitated, are susceptible to chemical influences in the environment once synthesized. In this paper, we characterize the minerals associated with freshwater FeOB stalks in order to evaluate key organo-mineral mechanisms involved in biomineral formation. Micro-Raman spectroscopy and Field Emission Scanning Electron Microscopy revealed that FeOB isolated from drinking water wells in Sweden produced stalks with ferrihydrite, lepidocrocite and goethite as main mineral components. Based on our observations made by micro-Raman Spectroscopy, field emission scanning electron microscopy and scanning transmission electron microscope combined with electron energy-loss spectroscopy, we propose a model that describes the crystal-growth mechanism, the Fe-oxidation state, and the mineralogical state of the stalks, as well as the biogenic contribution to these features. Our study suggests that the main crystal-growth mechanism in stalks includes nanoparticle aggregation and dissolution/re-precipitation reactions, which are dominant near the organic exopolymeric material produced by the microorganism and in the peripheral region of the stalk, respectively.

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