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Extracellular iron biomineralization by photoautotrophic iron-oxidizing bacteria.

ABSTRACT: 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 (alpha-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.

SUBMITTER: Miot J

PROVIDER: S-EPMC2737918 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature

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Extracellular iron biomineralization by photoautotrophic iron-oxidizing bacteria.

Miot Jennyfer J Benzerara Karim K Obst Martin M Kappler Andreas A Hegler Florian F Schädler Sebastian S Bouchez Camille C Guyot François F Morin Guillaume G

Applied and environmental microbiology 20090710 17

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 (alpha-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. Th ...[more]

PMID: 19592528

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Dataset Information

Extracellular iron biomineralization by photoautotrophic iron-oxidizing bacteria.

Publications

Extracellular iron biomineralization by photoautotrophic iron-oxidizing bacteria.

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