Schwertmannite formation at cell junctions by a new filament-forming Fe(II)-oxidizing isolate affiliated with the novel genus Acidithrix.
A new acidophilic iron-oxidizing strain (C25) belonging to the novel genus Acidithrix was isolated from pelagic iron-rich aggregates ('iron snow') collected below the redoxcline of an acidic lignite mine lake. Strain C25 catalysed the oxidation of ferrous iron [Fe(II)] under oxic conditions at 25 °C at a rate of 3.8 mM Fe(II) day(-1) in synthetic medium and 3.0 mM Fe(II) day(-1) in sterilized lake water in the presence of yeast extract, producing the rust-coloured, poorly crystalline mineral schwertmannite [Fe(III) oxyhydroxylsulfate]. During growth, rod-shaped cells of strain C25 formed long filaments, and then aggregated and degraded into shorter fragments, building large cell-mineral aggregates in the late stationary phase. Scanning electron microscopy analysis of cells during the early growth phase revealed that Fe(III)-minerals were formed as single needles on the cell surface, whereas the typical pincushion-like schwertmannite was observed during later growth phases at junctions between the cells, leaving major parts of the cell not encrusted. This directed mechanism of biomineralization at specific locations on the cell surface has not been reported from other acidophilic iron-oxidizing bacteria. Strain C25 was also capable of reducing Fe(III) under micro-oxic conditions which led to a dissolution of the Fe(III)-minerals. Thus, strain C25 appeared to have ecological relevance for both the formation and transformation of the pelagic iron-rich aggregates at oxic/anoxic transition zones in the acidic lignite mine lake.
Aquatic Geomicrobiology, Friedrich Schiller University Jena, Jena, Germany.
Jiro F
JF
Mori
The German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.|Aquatic Geomicrobiology, Friedrich Schiller University Jena, Jena, Germany.
Shipeng
S
Lu
Hydrogeology, Friedrich Schiller University Jena, Jena, Germany.
Matthias
M
Händel
Hydrogeology, Friedrich Schiller University Jena, Jena, Germany.
Kai Uwe
KU
Totsche
Department of River Ecology, Helmholtz Centre for Environmental Research-UFZ, Magdeburg, Germany.
Thomas R
TR
Neu
Institute of Physical Chemistry and Abbe School of Photonics, Friedrich Schiller University Jena, Jena, Germany.
Vasile Vlad
VV
Iancu
Institute of Physical Chemistry and Abbe School of Photonics, Friedrich Schiller University Jena, Jena, Germany.
Nicolae
N
Tarcea
Institute of Physical Chemistry and Abbe School of Photonics, Friedrich Schiller University Jena, Jena, Germany.|Institute of Photonic Technology, Jena, Germany.
Jürgen
J
Popp
Aquatic Geomicrobiology, Friedrich Schiller University Jena, Jena, Germany.|The German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany.
Kirsten
K
Küsel
D039903:Actinobacteria / Q000235:genetics / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D005296:Ferrous Compounds / Q000378:metabolism; D007365:Intercellular Junctions / Q000378:metabolism*; D058085:Iron Compounds / Q000378:metabolism*; D060106:Lakes / Q000737:chemistry / Q000382:microbiology*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010802:Phylogeny; D012914:Snow / Q000737:chemistry / Q000382:microbiology*
D005296:Ferrous Compounds; D058085:Iron Compounds; C511969:schwertmannite