Preparation and Characterization of Additional Metallic Element-Containing Tubular Iron Oxides of Bacterial Origin

Abstract

Biogenic microtubular iron oxides (BIOXs) derived from Leptothrix spp. are known as promising multifunctional materials for industrial applications such as ceramic pigments and catalyst carriers. Here, we report unprecedented BIOX products with additive depositions of various metallic elements prepared by a newly devised “two-step” method using an artificial culture system of Leptothrix cholodnii strain OUMS1; the method comprises a biotic formation of immature organic sheaths and subsequent abiotic deposition of Fe and intended elements on the sheaths. Chemical composition ratios of the additional elements Al, Zr, and Ti in the respective BIOXs were arbitrarily controllable depending on initial concentrations of metallic salts added to reaction solutions. Raman spectroscopy exemplified an existence of Fe–O–Al linkage in the Al-containing BIOX matrices. Time-course analyses revealed the underlying physiological mechanism for the BIOX formation. These results indicate that our advanced method can contribute greatly to creations of innovative bioderived materials with improved functionalities.

Eco-Benign Orange-Hued Pigment Derived from Aluminum-Enriched Biogenous Iron Oxide Sheaths

“…Previous studies have shown that the inclusion of Al in the chemically synthesized hematite-based pigments produced yellowish-red hues − and that the additive deposition of Al in BIOX-derived pigments resulted in an increased yellowish intensity . Using a two-step method, we have prepared highly enriched Al-containing cBIOX sheaths by the addition of 10 mM AlCl 3 solution over various concentrations of ZnSO 4 . Tube-shaped sheaths of cBIOX were successfully obtained at low concentrations of ZnSO 4 (≤10 mM), while an excess of sulfate ions might hinder the formation of cBIOX.…”

“… 17 , 18 Recent studies have shown that the chemical compositions of the cultured BIOX (cBIOX) sheaths are modifiable by biotemplate techniques using isolated iron bacterial strains. 19 , 20 Moreover, the additive elements deposited on the BIOX sheaths could readily improve the color tones in heated products, indicating that the BIOXs are easily tunable materials. 21 Herein, we describe new orange-hued iron oxide pigments with readily modifiable hues by changing the elemental composition in the BIOXs.…”

“…In ancient times, hematite pigments have been used for coloring murals and ornaments; nowadays, owing to their extremely low toxicity, wide availability, and high hiding power, these pigments are used for ceramics, cosmetics, exterior wall paintings, and road pavements. ,, Besides the mineral and chemical pathways of synthesizing iron oxides, the bioderived onesbiogenic iron oxide (BIOX)are considered promising raw materials for highly thermostable inorganic red pigments. , Interestingly, the BIOXs can have different morphologies such as: (i) unique microtubular sheath with high porousness, (ii) organic–inorganic hybrid construct composed mainly of primary nanoparticles of amorphous ferric oxyhydroxides, or (iii) nanocomposite structures formed by sintering. , Recent studies have shown that the chemical compositions of the cultured BIOX (cBIOX) sheaths are modifiable by biotemplate techniques using isolated iron bacterial strains. , Moreover, the additive elements deposited on the BIOX sheaths could readily improve the color tones in heated products, indicating that the BIOXs are easily tunable materials . Herein, we describe new orange-hued iron oxide pigments with readily modifiable hues by changing the elemental composition in the BIOXs.…”

Suppression of Bacterial Plant Diseases by Soil Admixture with Biogenous Iron Oxide Precipitates

“…Micromorphology and chemical composition were examined by scanning electron microscopy (SEM; S-4300, Hitachi, Tokyo, Japan) coupled with energy dispersive X-ray spectrometry (EDX; Genesis XM2, Ametek Inc., Tokyo, Japan). For investigation of the contacting states of BIOX sheaths with plant roots, living root sections were harvested carefully from BIOX−soil admixtures, rinsed with distilled water, and chemically fixed as described, 52 followed by the SEM analysis. Crystallographic analysis was performed by powder X-ray diffractometry (XRD; RINT-2000, Rigaku, Tokyo, Japan) using a monochromatic Cu−Kα radiation.…”

Study of biogenic iron oxyhydroxide for application in electronics and biotechnology

“…The need for reliable information on the structural and functional characteristics of nanosized materials produced by Leptothrix bacteria has grown in recent years [1][2][3]. The microaerophilic iron-oxidizing βproteobacteria from the genus Leptothrix are of great interest because during their growth they produce extracellular formations containing iron oxides and oxyhydroxides.…”