Structural model for the biogenic Mn oxide produced by Pseudomonas putida

By M. Villalobos, B. Lanson, A. Manceau, B. Toner, G. Sposito. 2006

330 citations recorded by the source corpus.

Abstract X-ray diffraction (XRD) and Mn K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy were combined to elaborate a structural model for phyllomanganates (layer-type Mn oxides) lacking 3D ordering (turbostratic stacking). These techniques were applied to a sample produced by a common soil and freshwater bacterium (Pseudomonas putida), and to two synthetic analogs, δ-MnO2 and acid birnessite, obtained by the reduction of potassium permanganate with MnCl2 and HCl, respectively. To interpret the diffraction and spectroscopic data, we applied an XRD simulation technique utilized previously for well-crystallized birnessite varieties, complementing this approach with single-scattering-path simulations of the Mn K-edge EXAFS spectra. Our structural analyses revealed that all three Mn oxides have an hexagonal layer symmetry with layers comprising edgesharing Mn4+O6 octahedra and cation vacancies, but no layer Mn3+O6 octahedra. The proportion of cation vacancies in the layers ranged from 6 to 17%, these vacancies being charge-compensated in the interlayer by protons, alkali metals, and Mn atoms, in amounts that vary with the phyllomanganate species and synthesis medium. Both vacancies and interlayer Mn were most abundant in the biogenic oxide. The diffracting crystallites contained three to six randomly stacked layers and have coherent scattering domains of 19.42 Å in the c* direction, and of 60.85 Å in the a-b plane. Thus, the Mn oxides investigated here are nanoparticles that bear significant permanent structural charge resulting from cation layer vacancies and variable surface charge from unsaturated O atoms at layer edges.

Subfields: Geochemistry and Petrology, Molecular Biology, Paleontology

View Paper: https://www.semanticscholar.org/paper/1a56d8fdb5aa576d780afe676baf54b467e98474

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In Geochemistry and Petrology

1. N. Geoffroy
2. A. Manceau
3. M. Marcus
4. B. Lanson
5. F. Panfili
6. S. Fakra
7. Sylvain Grangeon
8. M. Lanson

In Paleontology

1. N. Geoffroy
2. A. Manceau
3. B. Lanson
4. M. Marcus

Citations in the corpus

• Formation of Zn-Ca phyllomanganate nanoparticles in grass roots (2008, methodology): “Their profiles are controlled by the structure factor and can thus be used for structural determinations (Villalobos et al., 2006; Drits et al., 2007), as shown below.”
• Removal of Manganese(II) from Acid Mine Wastewater: A Review of the Challenges and Opportunities with Special Emphasis on Mn-Oxidizing Bacteria and Microalgae (2019, background): “The majority produced are amorphous nano-particulates [115], with high specific surface area and low isoelectric point [88].”
• Natural speciation of Ni, Zn, Ba, and As in ferromanganese coatings on quartz using X-ray fluorescence, absorption, and diffraction (2007, methodology): “The proportions of vacant Mn sites derived from chemical analysis are minimum values, because interlayer Mn could not be measured, and we know that this ion is often present (Lanson et al., 2000; Villalobos et al., 2006).”
• Structure of nanocrystalline phyllomanganates produced by freshwater fungi (2010, background): “…of randomly stacked layers of edge-sharing (Mn4+O6)8– octahedra (Giovanoli 1980), is the main biogenic Mn oxide (Jürgensen et al. 2004; Bargar et al. 2005; Webb et al. 2005; Villalobos et al. 2006; Lanson et al. 2008), possibly with tectomanganates, such as todorokite (e.g., Tebo et al. 2004).”