Abstract
Recent researches have shown that microbe–metal interactions play an important role in metal cycling and biomineralization in subsurface environments. The objective of this research was to study the effects of microbial growth conditions for size control on the synthesis of magnetite nanoparticles using Fe(III)-reducing bacteria enriched from intertidal flat sediments in Korea. The microbial formation of the magnetite nanoparticles was examined under various incubation temperatures (8–35 °C), concentrations (20–60 mM) of magnetite precursor, medium pHs (6.5–8.5), and incubation times (0–3 weeks). The Fe(III)-reducing bacteria formed 2~10 nm-sized magnetite (Fe3O4) by reduction of 40 mM akaganeite, especially under the conditions at 25 °C and medium pH = 8.5 within a 1-week incubation time. The magnetite nanoparticles formed by microbial processes exhibited superparamagnetic behavior.
Highlights
The synthesis of nano-sized minerals using microorganisms would receive an advantage from the development of clean, nontoxic, and environmentally acceptable chemistry procedures [1,2,3,4]
Of magnetite precursor ranged from 8 to 20 nm, shapes of magnetite nanoparticles appeared to have no differences (Figure 3e). These results indicate that magnetite crystals grow larger with increased concentrations of iron oxyhydroxide since the magnetite precursor plays a role in the nucleation of crystalline magnetite nanoparticles
The Fe(III)-reducing bacteria enriched from the inter-tidal flat sediments, Haejae-2, consist of Clostridium and unidentified species
Summary
The synthesis of nano-sized minerals using microorganisms would receive an advantage from the development of clean, nontoxic, and environmentally acceptable chemistry procedures [1,2,3,4]. The strain PV-4, Shewanella sp., isolated from iron-rich microbial mats at a hydrothermal vent, formed magnetite in a wide range of temperatures from 0 to 37 ◦ C, with the optimum rate at 18 ◦ C through microbial Fe(III)-reduction [13]. These studies revealed a potential for the synthesis of monodisperse magnetite nanoparticles using bacteria through the alteration of microbial growth conditions
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