|Miot, J; Benzerara, K; Obst, M; Kappler, A; Hegler, F; Schädler, S; Bouchez, C; Guyot, F; Morin, G: Extracellular Iron Biomineralization by Photoautotrophic Iron-Oxidizing Bacteria, Applied and Environmental Microbiology, 75(17), 5586 (2009), online: 10.07.2009, doi:5591 [Link]|
Iron oxidation at neutral pH by the phototrophic anaerobic iron-oxidizing bacterium Rhodobacter sp. strain SW2 leads to the formation of iron-rich minerals. These minerals consist mainly of nano-goethite (α-FeOOH), which precipitates exclusively outside cells, mostly on polymer fibers emerging from the cells. Scanning transmission X-ray microscopy analyses performed at the C K-edge suggest that these fibers are composed of a mixture of lipids and polysaccharides or of lipopolysaccharides. The iron and the organic carbon contents of these fibers are linearly correlated at the 25-nm scale, which in addition to their texture suggests that these fibers act as a template for mineral precipitation, followed by limited crystal growth. Moreover, we evidence a gradient of the iron oxidation state along the mineralized fibers at the submicrometer scale. Fe minerals on these fibers contain a higher proportion of Fe(III) at cell contact, and the proportion of Fe(II) increases at a distance from the cells. All together, these results demonstrate the primordial role of organic polymers in iron biomineralization and provide first evidence for the existence of a redox gradient around these nonencrusting, Fe-oxidizing bacteria.
Iron, sulfur and a pinch of antimony - new perspectives on secondary mineral pathways and metalloid mobility
Intensify or diversify? How agriculture affects biodiversity and ecosystem processes in European farmland
The meat of the Anthropocene: Food, capital and the globalisation of industrialised animal killing
Auf ins Neue! Winterspaziergang im ÖBG
Konzert: Musikalischer Jahresbeginn mit den Rockin`Dinos
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?