Leptothrix Ochracea Research Articles

Rare Earth Elements in Fe oxyhydroxides from biofilms containing iron-oxidizing bacteria

Fe oxyhydroxides extracted from modern-day biofilms with iron-oxidizing bacteria Arthrobacter spp., Gallionella spp и Leptothrix ochracea in the north-west of the East European platform display the enhanced content of rare earth elements – up to 1100 ppm. REE concentration in bacterial oxyhydroxides increase by one order in magnitude during 1 year suggesting the high sorption capacity of newly formed Fe mineral phases. La/YbN, Ce and Y anomalies in bacterial oxyhydroxides are consistent with geochemistry of the surface water facies where bacterial communities live. Isotopic composition of Nd in studied bacterial oxyhydroxides is controlled by the lithology of the Q-R underlying sediment and ambient water. 143Nd/144Nd values in Fe minerals of bacterial origin vary from 0.511570 to 0.512220 (eNd(0) from –21.8 to –9.2), the high proportion of radiogenic Nd is typical for the samples located on platform cover with Palaeozoic carbonate sediment.

Leptothrix ochracea genomes reveal potential for mixotrophic growth on Fe(II) and organic carbon.

Winogradsky's observations of L. ochracea led him to propose autotrophic iron oxidation as a new microbial metabolism, following his work on autotrophic sulfur-oxidizers. While much culture-based research has ensued, isolation proved elusive, so most work on L. ochracea has been based in the environment and in microcosms. Meanwhile, the autotrophic Gallionella became the model for freshwater microbial iron oxidation, while heterotrophic and mixotrophic iron oxidation is not well-studied. Ecological studies have shown that Leptothrix overtakes Gallionella when dissolved organic carbon content increases, demonstrating distinct niches. This study presents the first near-complete genomes of L. ochracea, which share some features with autotrophic iron oxidizers, while also incorporating heterotrophic metabolisms. These genome, metabolic modeling, and transcriptome results give us a detailed metabolic picture of how the organism may combine lithoautotrophy with organoheterotrophy to promote Fe oxidation and C cycling and drive many biogeochemical processes resulting from microbial growth and iron oxyhydroxide formation in wetlands.

Ferromanganese precipitates from the Jiawang Seamount, Bransfield Strait, Antarctica

The Jiawang Seamount is a young volcanic edifice in the central Bransfield Basin, Antarctica. Ferromanganese precipitates were collected from its top during the R/V “Xianghong 01” cruise during the austral summer season of 2017/2018. The mineralogical and chemical compositions of typical species were analyzed to decipher their origin. These ferromanganese fragments were very light in weight and characterized by channel/cavity structures. Their mineralogy was mainly amorphous Fe-Si oxyhydroxide, with minor amounts of pyrite, arsenopyrite and metal compounds. Geochemically, they were enriched in Fe and Si and depleted of Mn, with Mn/Fe ratios of approximately 0.009. Most trace elements were depleted in these species, but Mo and Ge were enriched relative to the elemental contents of the upper continental crust. Additionally, these samples were depleted in rare earth elements, with an average of 77.64 μg/g. The post-Archean Australian shale (PAAS)-normalized rare earth element (REE) patterns showed negative Eu anomalies but no Ce anomalies. Biomorphic-like structures were present in the samples, probably indicating that bacteria such as Leptothrix ochracea, Gallionella ferruginea and Mariprofundus ferrooxydans had, to some extent, affected sample formation. All of these facts also indicated that one mixing process (hydrothermal process and biological process) affected the ferromanganese deposits in the Bransfield Basin.

Influence of Probiotic Microorganisms on Microbial Biofilms in Feeds

At different stages of feed production and storage, it is possible to contaminate both feed and their components with various pathogenic and opportunistic microorganisms that can cause infectious diseases not only among animals but also have epidemiological significance. The aim of the study was to isolate biofilm-forming strains of microorganisms from feed, as well as to study the inhibitory activity of the probiotic complex of bacteria of the genus Bacillus against microbial biofilms. Identification and species affiliation of isolated bacterial field isolates were performed by cultural-morphological and biochemical properties. The formation of biofilms was studied by determining the ability of isolates of microbial associations and individual species of microorganisms to adhere to the surface of a 96-well polystyrene tablet according to the method of O'Toole & Kolter, 1998. Determination of microbial contamination of 50 industrial batches of feed from 4 pig farms in two regions of Ukraine (barley, compound feed SK-31 for rearing, SK-51 for fattening pigs, EXCELL starter for pigs 15%, shop prestarter, compound feed for lactating sows). In 11 experimental batches of barley (68.8%) and 13 batches of 3 types of feed (SK-31, SK-51, feed for lactating sows) identified associations with different microorganisms Pasteurella multocida, Corynebacterium striatum, Bacillus subtilis, Leptothrix ochracea, Haemophilus parasuis and yeast Candida albicans. The association of Actinobacillus pleuropneumonia bacteria with B. subtilis was identified in 2 batches (50%) of the shop prestarter. Moderate, by optical density, biofilm formation for associations of microorganisms P. multocida + C. striatum + C. albicans (D620=3.59) and P. multocida + L. ochracea + C. albicans (D620=3.62). Planktonic forms of C. striatum and P. multocida showed low film-forming activity at the level (D620<1.51). Inhibitory activity of the probiotic complex of bacteria of the genus Bacillus (B. subtilis, B. licheniformis, B. amyloliquefaciens) was determined by isolated variations of microbial biofilms in 5 feed species, which displaced all biofilm-forming microorganisms except H. parasuis

Green inhibitors reduce unwanted calcium carbonate precipitation: Implications for technical settings

Mineral scale deposits in water drainage and supply systems are a common and challenging issue, especially by clogging the water flow. The removal of such unwanted deposits is cost intensive arguing for case-specific and sustainable prevention strategies. In the present study, a novel on-site approach to prevent calcium carbonate (CaCO3) scale formation was assessed in two road tunnel drainages: Application of the eco-friendly green inhibitor polyaspartate (PASP) caused (i) a significant inhibition of CaCO3 precipitation, (ii) a more porous or even unconsolidated consistence of the deposits, and (iii) a shift from calcite to the metastable aragonite and vaterite polymorphs. Even relatively low PASP concentrations (1–33 mg/l) can significantly decrease CaCO3 scale deposition, removing up to ∼7 t CaCO3/year at an efficiency up to 84%. Application of PASP for water conditioning should also consider case-specific microbial activity effects, where consumption of PASP, e.g. by Leptothrix ochracea, can limit inhibition effects.

Hunter-Gatherers Harvested and Heated Microbial Biogenic Iron Oxides to Produce Rock Art Pigment

Red mineral pigment use is recognized as a fundamental component of a series of traits associated with human evolutionary development, social interaction, and behavioral complexity. Iron-enriched mineral deposits have been collected and prepared as pigment for use in rock art, personal adornment, and mortuary practices for millennia, yet little is known about early developments in mineral processing techniques in North America. Microanalysis of rock art pigments from the North American Pacific Northwest reveals a sophisticated use of iron oxide produced by the biomineralizing bacterium Leptothrix ochracea; a keystone species of chemolithotroph recognized in recent advances in the development of thermostable, colorfast biomaterial pigments. Here we show evidence for human engagement with this bacterium, including nanostructural and magnetic properties evident of thermal enhancement, indicating that controlled use of pyrotechnology was a key feature of how biogenic iron oxides were prepared into paint. Our results demonstrate that hunter-gatherers in this area of study prepared pigments by harvesting aquatic microbial iron mats dominated by iron-oxidizing bacteria, which were subsequently heated in large open hearths at a controlled range of 750 °C to 850 °C. This technical gesture was performed to enhance color properties, and increase colorfastness and resistance to degradation. This skilled production of highly thermostable and long-lasting rock art paint represents a specialized technological innovation. Our results contribute to a growing body of knowledge on historical-ecological resource use practices in the Pacific Northwest during the Late Holocene.Figshare link to figures: https://figshare.com/s/9392a0081632c20e9484.

Biogenous iron oxide (L-BIOX) as a high capacity anode material for lithium ion batteries

Biogenous iron oxide (L-BIOX) produced by Leptothrix ochracea aquatic bacteria, which is an amorphous Fe3+-based oxide that contains Si4+ and P5+ with tube-formed structures, has been studied for practical use as a conversion anode for lithium secondary batteries. L-BIOX has a capacity approximately two times larger than that of graphite. Conductive additives such as carbon nanotubes (CNTs) and Ketjen black (KB), of which the size and surface area are comparable to the primary nanoparticles of L-BIOX, are required to achieve good electrical contacts. Quasi-open circuit voltage (OCV) and X-ray photoelectron spectroscopy (XPS) measurements with respect to the discharge reveal that the conversion reaction occurs and solid electrolyte interphase (SEI) films are formed within the potential plateau area (1.8–1.5 V vs. Li). The water contained in L-BIOX is completely removed by heat-treatment at 400 °C. The elimination of water decreases the first irreversible capacity and improves the cycle performance. Li pre-doping by contact with Li metal realizes 100% coulombic efficiency at the first cycle. A lithium ion cell fabricated with a Li-pre-doped L-BIOX anode and a LiCoO2 cathode exhibits good cycle performance with high capacity retention.

A Model for Sheath Formation Coupled to Motility in Leptothrix ochracea

ABSTRACTOptical and atomic force microscopy (AFM) of naturally occurring Leptothrix ochracea was used to study the fine structure of sheaths and cells. Morphology of young sheaths suggests the scaffold chains have strong self-adhesion. Evidence from unencapsulated cells indicates fresh scaffold production through cell walls. Simple diffusion arguments are used to explain the morphology of the sheath structure. We propose a novel cell motility model based on previously published video data, our AFM images of naked cells, and simple flow calculations. The model indicates that motility results from differential shear forces resulting from extrusion of sheath material that passively pushes a filament of connected cells forward as the surrounding sheath material hardens behind the cell train.

Biogenous Iron Oxide(BIOX)-As a High-Capacity Anode Material for Lithium Ion Batteries

1.Introduction Biogenous iron oxide(BIOX) is produced by Leptothrix ochracea, aquatic bacteria living in the world. BIOX is amorphous Fe3+-based oxide containing Si and P, and takes tube-formed structure. In recent years, lithium-ion batteries have been widely used and intensively studied to meet an increasing variety of application in the future. Especially exploitation of high-capacity lithium-ion batteries is very important. The capacity of BIOX is approximately three times larger than that of graphite, so that BIOX is expected as a new high-capacity anode material for lithium ion batteries. BIOX belongs to the category of conversion anode materials and shows superior cycle and rate performance beyond normal conversion anode; however, the large first irreversible capacity remains in disadvantage for the practical use. In this study, we applied lithium pre-doping to BIOX electrode to eliminate the first irreversible capacity, and succeeded to provide the lithium ion battery with high capacity and high cycle performance.< 2.Experimental The BIOX cultured in Okayama university was firstly mixed with CNF (Carbon nanofiber) as a conductive agent, SBR (styrene-butadiene rubber) / CMC (carboxymethyl acid) as a binder (80:10:10 wt%) and water as a viscosity adjustor in an agate mortar. The slurry was coated on a copper foil, dried in air at 80ºC and vacuum-dried at 120ºC for 3h. The punched out electrode was pressed under the pressure of 2t. The first irreversible capacity was eliminated by contacting a lithium metal sheet to the electrode in an electrolyte (LiPF6in EC / DEC (1:1)). The charge-discharge behavior was measured in a coin type cell (2025) with Li metal as a counter electrode. The current rate was 0.1 C (the theoretical capacity of BIOX: 666mAh / g) and the voltage range was set between 50 and 3000mV 3.Results Figure 1 shows the voltage profiles of the first cycle for the as-prepared and Li- contacted electrodes. The former showed the first discharge capacity of 984mAh/g, and the following charged one of 712mAh/g. The first irreversible capacity is considerably large; the coulomb efficiency is only 72.0%. After the second cycle, almost 100% efficiency was obtained. On the other hand, the Li pre-doping by the contact of Li metal brought the high coulomb efficiency. The electrode of 30 s contacting of Li metal showed discharged capacity of 972mAh/g and charged one of 818mAh/g(coulomb efficiency:84.1% ). The first irreversible capacity due to the SEI formation on the nano-particles in BIOX may be compensable with the reaction of Li metal in advance. Figure 1

ChemInform Abstract: Bacteriogenic Iron Oxide as an Effective Catalyst for Baeyer—Villiger Oxidation with Molecular Oxygen and Benzaldehyde.

AbstractIron oxide produced by Leptothrix ochracea catalyzes the Baeyer—Villiger oxidation with molecular oxygen in the presence of benzaldehyde at 25°C.

Bacteriogenic iron oxide as an effective catalyst for Baeyer-Villiger oxidation with molecular oxygen and benzaldehyde

Iron oxide produced by iron-oxidizing bacteria, Leptothrix ochracea, (L-BIOX) obtained from a freshwater purification plant, Joyo City in Kyoto, Japan catalyzed Baeyer-Villiger oxidation with molecular oxygen in the presence of benzaldehyde at 25 °C more efficiently than usual iron compounds. L-BIOX can promote the reactions of various substrates to give the desired products in sufficient yields and was found to be reusable. Scanning transmission electron microscopy and 57Fe Mössbauer spectroscopy revealed that no change of the surface structure of L-BIOX was observed even after four times of the recycling test and the oxidation state of iron in L-BIOX is trivalent before and after the oxidation of cyclohexanone. An investigation with analogous amorphous iron oxides which contain silicon revealed that the catalytic activity of L-BIOX might stem from a synergetic effect of iron and silicon in the structure.

Structural transformations of heat-treated bacterial iron oxide

A bacterial siliceous iron oxide microtubule (diameter: ca. 1 μm, 15Fe2O3·8SiO2·P2O5·30H2O) produced by Leptothrix ochracea was heat treated in air and its structural transformation was investigated in detail by microscopy, diffractometry, and spectroscopy. Although the heat-treated bacterial iron oxide retained its original microtubular structure, its nanoscopic, middle-range, and local structures changed drastically. Upon heat treatment, nanosized pores were formed and their size changed depending on temperature. The Fe–O–Si linkages were gradually cleaved with increasing temperature, causing the progressive separation of Fe and Si ions into iron oxide and amorphous silicate phases, respectively. Concomitantly, global connectivity and local structure of FeO6 octahedra in the iron oxide nanoparticles systematically changed depending on temperature. These comprehensive investigations clearly revealed various structural changes of the bacterial iron oxide which is an important guideline for the future exploration of novel bio-inspired materials.

Bacterial Nanometric Amorphous Fe-Based Oxide: A Potential Lithium-Ion Battery Anode Material

Amorphous Fe(3+)-based oxide nanoparticles produced by Leptothrix ochracea, aquatic bacteria living worldwide, show a potential as an Fe(3+)/Fe(0) conversion anode material for lithium-ion batteries. The presence of minor components, Si and P, in the original nanoparticles leads to a specific electrode architecture with Fe-based electrochemical centers embedded in a Si, P-based amorphous matrix.

Ecological succession among iron-oxidizing bacteria

Despite over 125 years of study, the factors that dictate species dominance in neutrophilic iron-oxidizing bacterial (FeOB) communities remain unknown. In a freshwater wetland, we documented a clear ecological succession coupled with niche separation between the helical stalk-forming Gallionellales (for example, Gallionella ferruginea) and tubular sheath-forming Leptothrix ochracea. Changes in the iron-seep community were documented using microscopy and cultivation-independent methods. Quantification of Fe-oxyhydroxide morphotypes by light microscopy was coupled with species-specific fluorescent in situ hybridization (FISH) probes using a protocol that minimized background fluorescence caused by the Fe-oxyhydroxides. Together with scanning electron microscopy, these techniques all indicated that Gallionellales dominated during early spring, with L. ochracea becoming more abundant for the remainder of the year. Analysis of tagged pyrosequencing reads of the small subunit ribosomal RNA gene (SSU rRNA) collected during seasonal progression supported a clear Gallionellales to L. ochracea transition, and community structure grouped according to observed dominant FeOB forms. Axis of redundancy analysis of physicochemical parameters collected from iron mats during the season, plotted with FeOB abundance, corroborated several field and microscopy-based observations and uncovered several unanticipated relationships. On the basis of these relationships, we conclude that the ecological niche of the stalk-forming Gallionellales is in waters with low organic carbon and steep redoxclines, and the sheath-forming L. ochracea is abundant in waters that contain high concentrations of complex organic carbon, high Fe and Mn content and gentle redoxclines. Finally, these findings identify a largely unexplored relationship between FeOB and organic carbon.

Nano–Micrometer-Architectural Acidic Silica Prepared from Iron Oxide of Leptothrix ochracea Origin

We prepared nano-micrometer-architectural acidic silica from a natural amorphous iron oxide with structural silicon which is a product of the iron-oxidizing bacterium Leptothrix ochracea. The starting material was heat-treated at 500 °C in a H2 gas flow leading to segregation of α-Fe crystalline particles and then dissolved in 1 M hydrochloric acid to remove the α-Fe particles, giving a gray-colored precipitate. It was determined to be amorphous silica containing some amount of iron (Si/Fe = ~60). The amorphous silica maintains the nano-microstructure of the starting material-~1-μm-diameter micrometer-tubules consisting of inner globular and outer fibrillar structures several tens of nanometer in size-and has many large pores which are most probably formed as a result of segregation of the α-Fe particles on the micrometer-tubule wall. The smallest particle size of the amorphous silica is ~10 nm, and it has a large surface area of 550 m(2)/g with micropores (0.7 nm). By using pyridine vapor as a probe molecule to evaluate the active sites in the amorphous silica, we found that it has relatively strong Brønsted and Lewis acidic centers that do not desorb pyridine, even upon evacuation at 400 °C. The acidity of this new silica material was confirmed through representative two catalytic reactions: ring-opening reaction and Friedel-Crafts-type reaction, both of which are known to require acid catalysts.

Hidden in plain sight: discovery of sheath-forming, iron-oxidizingZetaproteobacteriaat Loihi Seamount, Hawaii, USA

Lithotrophic iron-oxidizing bacteria (FeOB) form microbial mats at focused flow or diffuse flow vents in deep-sea hydrothermal systems where Fe(II) is a dominant electron donor. These mats composed of biogenically formed Fe(III)-oxyhydroxides include twisted stalks and tubular sheaths, with sheaths typically composing a minor component of bulk mats. The micron diameter Fe(III)-oxyhydroxide-containing tubular sheaths bear a strong resemblance to sheaths formed by the freshwater FeOB, Leptothrix ochracea. We discovered that veil-like surface layers present in iron-mats at the Loihi Seamount were dominated by sheaths (40-60% of total morphotypes present) compared with deeper (> 1 cm) mat samples (0-16% sheath). By light microscopy, these sheaths appeared nearly identical to those of L. ochracea. Clone libraries of the SSU rRNA gene from this top layer were dominated by Zetaproteobacteria, and lacked phylotypes related to L. ochracea. In mats with similar morphologies, terminal-restriction fragment length polymorphism (T-RFLP) data along with quantitative PCR (Q-PCR) analyses using a Zetaproteobacteria-specific primer confirmed the presence and abundance of Zetaproteobacteria. A Zetaproteobacteria fluorescence in situ hybridization (FISH) probe hybridized to ensheathed cells (4% of total cells), while a L. ochracea-specific probe and a Betaproteobacteria probe did not. Together, these results constitute the discovery of a novel group of marine sheath-forming FeOB bearing a striking morphological similarity to L. ochracea, but belonging to an entirely different class of Proteobacteria.

Robust porphyrin catalysts immobilized on biogenous iron oxide for the repetitive conversions of epoxides and CO2 into cyclic carbonates

Metalloporphyrins were immobilized on biogenous iron oxide (BIO) produced by iron-oxidizing bacteria, Leptothrix ochracea. These organic–inorganic hybrid materials were used as immobilized catalysts for the synthesis of cyclic carbonates from epoxides and CO2 under solvent-free conditions. ZnII porphyrin immobilized via four tetraalkylammonium bromide groups showed high catalytic activity and reusability at a catalyst loading of 0.1 mol%. The product was obtained in 99% yield after nine times reuse, and the substrate scope was broad.

Nano–micro-architectural composites with acid properties: Magnetic iron oxides/amorphous silicate prepared from iron oxide produced by iron-oxidizing bacterium, Leptothrix ochracea

To develop novel magnetic composites with acid functionalities, iron oxide produced by iron-oxidizing bacterium, Leptothrix ochracea, was used as a precursor. The composites were prepared by thermal treatment and subsequent reduction of the bacterial iron oxide. α-Fe2O3 nanoparticles obtained in air were thermally reduced to Fe3O4 and gradually oxidized to γ-Fe2O3. The obtained composites with Fe3O4 and γ-Fe2O3 have high magnetization values that are approximately half those of pure Fe3O4 and γ-Fe2O3. All samples have an interesting nano–micro-architectural structure: ∼40-nm-diameter crystalline particles covered with ∼8-nm-thick amorphous silicate are intricately interconnected into ∼1-μm-diameter microtubules. Pyridine adsorption spectra indicate that the surface amorphous silicate has both Brönsted and Lewis acid properties.

Amorphous structure of iron oxide of bacterial origin

In nature, there are various iron oxides produced by the water-habitant bacterial group called “iron-oxidizing bacteria”. These iron oxides have been studied mainly from biological and geochemical perspectives. Today, attempts are made to use such iron oxides as novel functional materials in several applications. However, their quantitative structural characteristics are still unclear. We studied the structure of iron oxide of microtubular form consisting of amorphous nanoparticles formed by an iron-oxidizing bacterium, Leptothrix ochracea, using a combination of high-energy X-ray diffraction and reverse Monte Carlo simulation. We found that its structure consists of a framework of corner- and edge-sharing distorted FeO6 octahedral units, while SiO4 tetrahedral units are isolated in the framework. The results reveal the atomic arrangement of iron oxide of bacterial origin, which is essential for investigating its potential as a functional material.

Synthesis and magnetic properties of magnetite-silicate nanocomposites derived from iron oxide of bacterial origin

Magnetic nanocomposites containing magnetite (Fe3O4) nanoparticles were prepared from iron oxide microtubules produced by Leptothrix ochracea, a species of water-habitant iron-oxidizing bacteria. The microtubules were mainly composed of Si-containing ferric hydroxide that shows a broad X-ray diffraction pattern similar to that of 2-line ferrihydrite. After moderate heat treatment in a reductive atmosphere above 325°C, the ferric ions were partially reduced to a ferrous state, and nanocrystalline Fe3O4 with a spinel-type structure was formed in a noncrystalline silicate matrix. The average crystallite size of the Fe3O4 nanoparticles was estimated to be in the order of a few nanometers. The sample heat-treated at 500°C exhibited considerable magnetization together with superparamagnetic behavior at room temperature, and super-spin-glass interaction occurred at low temperature. On further heat treatment above 530°C, Fe3O4 was reduced to wüstite (Fe1−xO) and finally crystallized into iron metal (α-Fe) and ferrous silicate (Fe2SiO4).