|Pantke, C; Obst, M; Benzerara, K; Morin, G; Ona-Nguema, G; Dippon, U; Kappler, A: Green Rust Formation during Fe(II) Oxidation by the Nitrate-Reducing Acidovorax sp. Strain BoFeN1, Environmental Science and Technology, 46(3), 1439-1446 (2012), online: 22.12.2011, doi:10.1021/es2016457 [Link]|
Green rust (GR) as highly reactive iron mineral potentially plays a key role for the fate of (in)organic contaminants, such as chromium or arsenic, and nitroaromatic compounds functioning both as sorbent and reductant. GR forms as corrosion product of steel but is also naturally present in hydromorphic soils and sediments forming as metastable intermediate during microbial Fe(III) reduction. Although already suggested to form during microbial Fe(II) oxidation, clear evidence for GR formation during microbial Fe(II) oxidation was lacking. In the present study, powder XRD, synchrotron-based XAS, Mössbauer spectroscopy, and TEM demonstrated unambiguously the formation of GR as an intermediate product during Fe(II) oxidation by the nitrate-reducing Fe(II)-oxidizer Acidovorax sp. strain BoFeN1. The spatial distribution and Fe redox-state of the precipitates associated with the cells were visualized by STXM. It showed the presence of extracellular Fe(III), which can be explained by Fe(III) export from the cells or extracellular Fe(II) oxidation by an oxidant diffusing from the cells. Moreover, GR can be oxidized by nitrate/nitrite and is known as a catalyst for oxidation of dissolved Fe(II) by nitrite/nitrate and may thus contribute to the production of extracellular Fe(III). As a result, strain BoFeN1 may contribute to Fe(II) oxidation and nitrate reduction both by an direct enzymatic pathway and an indirect GR-mediated process.
Prof. Tillmann Lüders: Aktiv im Untergrund - die Bedeutung der Mikroben für die Grundwasserqualität
Inside the fog: towards an improved forecasting of nocturnal fog by using turbulence-resolving simulations
Umweltseismologie und ihre Bedeutung zur Abschätzung geomorphologischer Risiken
Bittersüßer Wohlgeschmack: "Kolonialpflanzen"
Ausstellungseröffnung: Farben-Pflanzen-Pflanzenfarben - Malerei von Angelika Gigauri
Stoichiometric controls of C and N cycling
Flying halfway across the globe to dig in the dirt – a research stay in Bloomington, USA
EGU – interesting research and free coffee
Picky carnivorous plants?