Removal of soluble strontium via incorporation into biogenic carbonate minerals by halophilic bacterium Bacillus sp. strain TK2d in a highly saline solution

Takumi Horiike, Yuma Dotsuta, Yuriko Nakano, Asumi Ochiai, Satoshi Utsunomiya, Toshihiko Ohnuki, Mitsuo Yamashita

Research output: Contribution to journalArticle

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Abstract

Radioactive strontium (90Sr) leaked into saline environments, including the ocean, from the Fukushima Daiichi Nuclear Power Plant after a nuclear accident. Since the removal of 90Sr using general adsorbents (e.g., zeolite) is not efficient at high salinity, a suitable alternative immobilization method is necessary. Therefore, we incorporated soluble Sr into biogenic carbonate minerals generated by ureaseproducing microorganisms from a saline solution. An isolate, Bacillus sp. strain TK2d, from marine sediment removed > 99% of Sr after contact for 4 days in a saline solution (1.0 × 10-3 mol liter-1 of Sr, 10% marine broth, and 3% [wt/vol] NaCl). Transmission electron microscopy and energy-dispersive X-ray spectroscopy showed that Sr and Ca accumulated as phosphate minerals inside the cells and adsorbed at the cell surface at 2 days of cultivation, and then carbonate minerals containing Sr and Ca developed outside the cells after 2 days. Energy-dispersive spectroscopy revealed that Sr, but not Mg, was present in the carbonate minerals even after 8 days. X-ray absorption fine-structure analyses showed that a portion of the soluble Sr changed its chemical state to strontianite (SrCO3) in biogenic carbonate minerals. These results indicated that soluble Sr was selectively solidified into biogenic carbonate minerals by the TK2d strain in highly saline environments.

LanguageEnglish
Article numbere00855-17
JournalApplied and Environmental Microbiology
Volume83
Issue number20
DOIs
StatePublished - 2017

Fingerprint

carbonate minerals
strontium
Bacillus (bacteria)
sodium chloride
carbonate
bacterium
bacteria
mineral
spectroscopy
X-radiation
phosphate minerals
nuclear power
energy
power plants
nuclear accident
adsorbents
marine sediments
cells
accidents
strontium isotope

Keywords

  • Biomineralization
  • Bioremediation
  • Halophilic
  • Marine environment
  • Radionuclide
  • Urease

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

Cite this

Removal of soluble strontium via incorporation into biogenic carbonate minerals by halophilic bacterium Bacillus sp. strain TK2d in a highly saline solution. / Horiike, Takumi; Dotsuta, Yuma; Nakano, Yuriko; Ochiai, Asumi; Utsunomiya, Satoshi; Ohnuki, Toshihiko; Yamashita, Mitsuo.

In: Applied and Environmental Microbiology, Vol. 83, No. 20, e00855-17, 2017.

Research output: Contribution to journalArticle

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abstract = "Radioactive strontium (90Sr) leaked into saline environments, including the ocean, from the Fukushima Daiichi Nuclear Power Plant after a nuclear accident. Since the removal of 90Sr using general adsorbents (e.g., zeolite) is not efficient at high salinity, a suitable alternative immobilization method is necessary. Therefore, we incorporated soluble Sr into biogenic carbonate minerals generated by ureaseproducing microorganisms from a saline solution. An isolate, Bacillus sp. strain TK2d, from marine sediment removed > 99{\%} of Sr after contact for 4 days in a saline solution (1.0 × 10-3 mol liter-1 of Sr, 10{\%} marine broth, and 3{\%} [wt/vol] NaCl). Transmission electron microscopy and energy-dispersive X-ray spectroscopy showed that Sr and Ca accumulated as phosphate minerals inside the cells and adsorbed at the cell surface at 2 days of cultivation, and then carbonate minerals containing Sr and Ca developed outside the cells after 2 days. Energy-dispersive spectroscopy revealed that Sr, but not Mg, was present in the carbonate minerals even after 8 days. X-ray absorption fine-structure analyses showed that a portion of the soluble Sr changed its chemical state to strontianite (SrCO3) in biogenic carbonate minerals. These results indicated that soluble Sr was selectively solidified into biogenic carbonate minerals by the TK2d strain in highly saline environments.",
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