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Minerals 2018, 8(3), 98; https://doi.org/10.3390/min8030098

Biosynthesis of Schwertmannite and Goethite in a Bioreactor with Acidophilic Fe(II)-Oxidizing Betaproteobacterium Strain GJ-E10

1
Department of Biological Environment, Akita Prefectural University, Shimoshinjo-Nakano, Akita 010-0195, Japan
2
Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushimanaka, Okayama 700-8530, Japan
3
Department of Applied Chemistry, School of Advanced Engineering, Kogakuin University, 2665-1 Nakano, Hachioji, Tokyo 192-0015, Japan
4
Japan Science and Technology Agency (JST), Core Research for Evolutional Science and Technology (CREST), 3-1-1 Tsushimanaka, Okayama 700-8530, Japan
*
Author to whom correspondence should be addressed.
Received: 12 February 2018 / Revised: 28 February 2018 / Accepted: 1 March 2018 / Published: 4 March 2018
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Abstract

Iron oxide minerals, schwertmannite and goethite, which are naturally occurring in acidic environments are attractive nanostructured materials because of the potential diverse applications. Although the biosynthesis of schwertmannite by acidophilic Fe(II)-oxidizing microorganisms has been investigated, little is known about goethite biosynthesis under acidic conditions. To examine a biological approach to the synthesis of these minerals, bioreactor experiments were conducted with a newly isolated acidophilic betaproteobacterium. The bioproducts were characterized by powder X-ray diffraction, cryogenic Mössbauer spectroscopy, and electron microscopy. The cultures growing at 25 °C and pH 3.0 or at 37 °C and pH 2.5 oxidized Fe(II) and precipitated schwertmannite rapidly. Increasing pH at each temperature resulted in the concomitant production of goethite, and 90% pure goethite was obtained at 37 °C and pH 3.5. The goethite phase was nano-sized and had relatively large specific surface area (133 m2·g−1), leading to high sorption capacity for metal oxyanions. Schwertmannite was also a good adsorbent for oxyanions, regardless of the smaller specific surface area. Our results indicate that these acidophilic microbial cultures serve as a simple rapid system for the synthesis of nanostructured goethite as well as schwertmannite. View Full-Text
Keywords: acidophilic iron-oxidizing bacterium; goethite; metal oxyanion sorption; Mössbauer spectroscopy; schwertmannite acidophilic iron-oxidizing bacterium; goethite; metal oxyanion sorption; Mössbauer spectroscopy; schwertmannite
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Miyata, N.; Takahashi, A.; Fujii, T.; Hashimoto, H.; Takada, J. Biosynthesis of Schwertmannite and Goethite in a Bioreactor with Acidophilic Fe(II)-Oxidizing Betaproteobacterium Strain GJ-E10. Minerals 2018, 8, 98.

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