Mihály Pósfai

Mihály Pósfai
University of Pannonia, Veszprém · Department of Earth and Environmental Science

Professor

About

166
Publications
31,678
Reads
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8,376
Citations
Citations since 2017
48 Research Items
3242 Citations
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
Introduction
Additional affiliations
September 1994 - present
University of Pannonia, Veszprém
Position
  • Professor (Full)
March 1992 - August 1998
Arizona State University
Position
  • PostDoc Position

Publications

Publications (166)
Article
Full-text available
Horizontal gene transfer is a powerful source of innovations in prokaryotes that can affect almost any cellular system, including microbial organelles. The formation of magnetosomes, one of the most sophisticated microbial mineral-containing organelles synthesized by magnetotactic bacteria for magnetic navigation in the environment, was also shown...
Article
Full-text available
Since carbonate formation is an important process linking inorganic and biological components of freshwater ecosystems, we characterized the formation of modern carbonate sediments in a large, shallow, calcareous lake (Lake Balaton in Hungary). We measured the amount of allochtonous mineral particles delivered to the lake by tributaries and through...
Article
Full-text available
Diesel and petrol powered vehicles are contributors to the magnetic fraction of atmospheric particles in the urban atmosphere. For an assessment of the health effects of vehicle-emitted magnetic particles, the mineralogical characters of particles present in engine exhaust vs. those produced by braking need to be understood. We collected magnetical...
Article
Full-text available
Metal sulfides are a common group of extracellular bacterial biominerals. However, only a few cases of intracellular biomineralization are reported in this group, mostly limited to greigite (Fe3S4) in magnetotactic bacteria. Here, a previously unknown periplasmic biomineralization of copper sulfide produced by the magnetotactic bacterium Desulfampl...
Article
Bacteria play crucial roles in the biogeochemical cycle of arsenic (As) and selenium (Se) as these elements are metabolized via detoxification, energy generation (anaerobic respiration) and biosynthesis (e.g. selenocysteine) strategies. To date, arsenic and selenium biomineralization in bacteria were studied separately. In this study, the anaerobic...
Conference Paper
Full-text available
Shewanella sp. O23S (Shewanella baltica) was isolated from a dissimilatory arsenate-reducing bacteria (DARB) microbial mat that inhabits the bottom sediments from an ancient gold mine (Złoty Stok, SW Poland) [1]. This strain is unusual in its versatile metabolism of selenium (Se) and arsenic (As), being capable of both detoxification and respiratio...
Preprint
Full-text available
Magnetosomes are unique organelles synthesized by magnetotactic bacteria (MTB) for magnetic navigation. Their complex biosynthesis is controlled by large magnetosome gene clusters (MGC). Here, we report the discovery and comprehensive analysis of silent but functional MGCs in the non-magnetotactic phototrophic bacterium Rhodovastum atsumiense. Our...
Preprint
Full-text available
Metal sulfides are a common group of extracellular bacterial biominerals. Only few cases of intracellular biomineralization have been reported in this group, mostly limited to greigite (Fe3S4) in magnetotactic bacteria. Here, we report the intracellular but periplasmic biomineralization of copper sulfide by the magnetotactic bacterium Desulfamplus...
Preprint
Full-text available
Metal sulfides are a common group of extracellular bacterial biominerals. Only few cases of intracellular biomineralization have been reported in this group, mostly limited to greigite (Fe3S4) in magnetotactic bacteria. Here, we report the intracellular but periplasmic biomineralization of copper sulfide by the magnetotactic bacterium Desulfamplus...
Article
The treatment of metal‐laden industrial effluents by reverse osmosis is gaining in popularity worldwide due to its high performance. However, this process generates a polymetallic concentrate (retentate) stream in need of efficient post‐treatment prior to environmental discharge. This paper presents results on the bioremediation (in batch mode) of...
Article
Full-text available
The effects of pre-existing mineral phases on the nucleation and growth of calcium carbonates from solution are relatively poorly understood, despite the widespread co-occurrence of carbonate minerals with clays and other silicates in rocks, soils, and sediments. Previous studies suggested that sheet silicates template calcite nucleation. Moreover,...
Preprint
Micro-and nano-inclusions embedded in calcite phantom crystals from Gemerská Ves, Slovakia, have been characterized by a combination of Raman spectroscopy, scanning and transmission electron microscopy, X-ray powder diffraction, and C and O isotope analysis. Whereas the outer, colorless part of the phantom crystal is relatively homogeneous, cavity...
Article
Exposure to particulate air pollution has been associated with a variety of respiratory, cardiovascular and neurological problems, resulting in increased morbidity and mortality worldwide. Brake-wear emissions are one of the major sources of metal-rich airborne particulate pollution in roadside environments. Of potentially bioreactive metals, Fe (e...
Article
Full-text available
Crystal formation via amorphous precursors is a long-sought-after gateway to engineer nanoparticles with well-controlled size and morphology. Biomineralizing organisms, like magnetotactic bacteria, follow such a nonclassical crystallization pathway to produce magnetite nanoparticles with sophistication unmatched by synthetic efforts at ambient cond...
Conference Paper
Full-text available
Industry is constantly searching for methods to treat waste fluxes in an attempt to minimize its environmental impact. Reverse osmosis (RO) is an efficient treatment system, generating a permeate stream (purified water passing through the membrane) and a retentate stream, which concentrates the constituents rejected by the membrane. Currently, a ho...
Article
Full-text available
Pyrrhotites, characterized by the chemical formula Fe1–δS (0 < δ ≤ 1/8), represent an extended group of minerals that are derived from the NiAs-type FeS aristotype. They contain layered arrangements of ordered Fe vacancies, which are at the origin of the various magnetic signals registered from certain natural rocks and can act as efficient electro...
Article
Full-text available
A Balaton holocén üledékének tudományos kutatása közel 130 éve kezdődött. Az üledék felhalmozódásának törvényszerűségeit, az iszap összetételét, a tavi tápanyagforgalomban töltött szerepét a 20. század második felében viszonylag alaposan megismertük. Ennek ellenére a mai, modern geokémiai és ásványtani módszerekkel végzett vizsgálatok mindig újabb...
Article
Full-text available
Catalysts for visible-light-driven oxidative cleaning processes and antibacterial applications (also in the dark) were developed. In order to extend the photoactivity of titanium dioxide into the visible region, nitrogen-doped TiO2 catalysts with hollow and non-hollow structures were synthesized by co-precipitation (NT-A) and sol–gel (NT-U) methods...
Article
Full-text available
One-dimensional kaolinite nanoscrolls have been arousing great interest due to their applicability in advanced materials for adsorption and slow release of reagents, as well as in nanoscale reactors and carriers. Production of high-quality halloysite-like nanoscrolls with controlled morphology, however, remains challenging as there is a lack of und...
Article
Full-text available
Bacillus sp. Abq, belonging to Bacillus cereus sensu lato, was isolated from an aquifer in New Mexico, USA and phylogenetically classified. The isolate possesses the unusual property of precipitating Pb(II) by using cysteine, which is degraded intracellularly to hydrogen sulfide (H2S). H2S is then exported to the extracellular environment to react...
Article
In many environments calcium carbonate minerals precipitate in the presence of clay minerals, and observations suggest that clays, particularly smectites, facilitate carbonate formation. In order to understand the interactions between clay surfaces and carbonate-precipitating solutions, we built model aqueous solutions of various compositions (cont...
Poster
Full-text available
The formation of calcium carbonate minerals in lakes is typically linked to biological activity; however, our previous results suggest that in a large, shallow lake smectite clay minerals facilitate the nucleation of Mg-bearing calcite [1]. Furthermore, nucleation and growth on the clay surface likely affects grain size and morphology. In the prese...
Article
Both inorganic and microbial processes play important roles in carbonate mineral precipitation in freshwater lakes. Identifying the individual factors that determine particle size, shape, composition, and the spatial relationships of carbonates with other constituents of the sediment are important for understanding sediment formation and nutrient c...
Article
Full-text available
The chemical properties of tar ball (TB) particles generated from dry distillate (wood tars) of three different wood species in the laboratory were investigated by analytical techniques that had never been used before, for their characterization. The elemental composition of TB particles from three tree species were very similar to one another and...
Article
Full-text available
In this work we addressed the problem how to fabricate self-assembling tubular nanostructures displaying target recognition functionalities. Bacterial flagellar filaments, composed of thousands of flagellin subunits, were used as scaffolds to display single-domain antibodies (nanobodies) on their surface. As a representative example, an anti-GFP na...
Article
Full-text available
With the aim of creating one-dimensional magnetic nanostructures, we genetically engineered flagellar filaments produced by Salmonella bacteria to display iron- or magnetite-binding sites, and used the mutant filaments as templates for both nucleation and attachment of the magnetic iron oxide magnetite. Although nucleation from solution and attachm...
Article
Full-text available
Black carbon (BC) aerosols have often been assumed to be the only light-absorbing carbonaceous particles in the red and near-infrared spectral regions of solar radiation in the atmosphere. Here we report that tar balls (a specific type of organic aerosol particles from biomass burning) do absorb red and near-infrared radiation significantly. Tar ba...
Article
Full-text available
Black carbon (BC) aerosols have often been assumed to be the only light-absorbing carbonaceous particles in the red and near-infrared spectral regions of solar radiation in the atmosphere. Here we report that tar balls (a specific type of organic aerosol particles from biomass burning) do absorb red and near-infrared radiation significantly. Tar ba...
Article
Full-text available
Magnetite nanoparticles exhibit magnetic properties that are size and organization dependent and, for applications that rely on their magnetic state, they usually have to be monodisperse. Forming such particles, however, has remained a challenge. Here, we synthesize 40 nm particles of magnetite in the presence of polyarginine and show that they are...
Article
Full-text available
Black carbon aerosols (BC) have been conventionally assumed to be the only light-absorbing carbonaceous particles in the red and near-infrared spectral regions of solar radiation in the atmosphere. Here we report that contrary to the conventional belief tar balls (a specific type of organic aerosol particles from biomass burning) do absorb red and...
Chapter
Full-text available
Lake Balaton can be regarded as a large scientific laboratory in which many interesting aspects of carbonate mineral formation can be studied, with relevance to the general understanding of nanoscale processes that govern crystal nucleation and growth in a natural aqueous system. The lake is extremely shallow for its size (on average 3.5 m deep and...
Article
This work aims at developing a novel method for fabricating 1D magnetite nanostructures with the help of mutagenized flagellar filaments. We constructed four different flagellin mutants displaying magnetite-binding motifs. Two of the mutants contained fragments of magnetosome-associated proteins from magnetotactic bacteria (MamI and Mms6), whereas...
Article
Full-text available
Black carbon aerosols have been conventionally assumed to be the only light-absorbing carbonaceous particles in the red and near-infrared spectral regions of solar radiation in the atmosphere. Here we report that contrary to the conventional belief tar balls (a specific type of organic aerosol particles from biomass burning) do absorb red and near...
Article
Full-text available
Tar balls (TBs) are a specific particle type that is abundant in the global troposphere, in particular in biomass smoke plumes. These particles belong to the family of atmospheric brown carbon (BrC), which can absorb light in the visible range of the solar spectrum. Albeit TBs are typically present as individual particles in biomass smoke plumes, t...
Article
Technological advancements of the Magnetic Particle Imaging (MPI) scanner and image reconstruction are im- portant steps in the process of bringing MPI to preclinical and clinical applications. The future of this promising imaging modality, however, also crucially relies on the development of MPI tracers with high performance. An interesting materi...
Article
Full-text available
Tar balls (TBs) are a specific particle type which is abundant in the global troposphere, in particular in biomass smoke plumes. These particles belong to the family of atmospheric brown carbon (BrC) which can absorb light in the visible range of the solar spectrum. Albeit TBs are typically present as individual particles in biomass smoke plumes, t...
Article
Day-Dunlop plots are widely used in paleomagnetic and environmental studies as a tool to determine the magnetic domain state of magnetite, i.e., superparamagnetic (SP), stable single-domain (SD), pseudosingle-domain (PSD), multidomain (MD), and their mixtures. The few experimental studies that have examined hysteresis properties of SD-SP mixtures o...
Article
Full-text available
Magnetite nanoparticles, especially superparamagnetic iron oxide nanoparticles, are established contrast agents for magnetic resonance imaging. Magnetosomes, which are magnetite nanoparticles of biological origin, have been shown to have better contrast properties than current formulations possibly because of their larger size and high monodispersi...
Article
Full-text available
Magnetic nanoparticles encompass a wide range of scientific study and technological applications. The success of using the nanoparticles in various applications demands control over size, dispersibility, and magnetics. Hence, the nanoparticles are often characterized by transmission electron microscopy (TEM), X-ray diffraction, and magnetic hystere...
Article
Magnetite is an iron oxide found in rocks. Its magnetic properties are used for paleoclimatic reconstructions. It can also be synthesized in the laboratory to exploit its magnetic properties for bio- and nanotechnological applications. However, although the magnetic properties depend on particle size in a well-understood manner, they also depend on...
Article
Full-text available
Atmospheric tar balls are particles of special morphology and composition that are fairly abundant in the plumes of biomass smoke. These particles form a specific subset of brown carbon (BrC) which has been shown to play a significant role in atmospheric shortwave absorption and, by extension, climate forcing. Here we suggest that tar balls are pro...
Article
Full-text available
The climate-change and environmental literature, including that on aerosols, is replete with mention of black carbon (BC) and soot. The terms are used interchangeably in much of the literature, although BC and soot commonly have operational and source-based definitions, respectively, and reliable reference samples and aerosol standards do not exist...
Article
Full-text available
Lake Balaton is a large and shallow lake that is of great economic and cultural importance in landlocked Hungary. Even though the lake has been studied extensively in the last century from a large number of scientific aspects, the mineralogy of its sediments has not been fully explored. The mud at the bottom of the lake consists mostly of silt-size...
Article
Biosynthesis of bacterial magnetosomes, which are intracellular membrane-enclosed, nanosized magnetic crystals, is controlled by a set of >30 specific genes. In Magnetospirillum gryphiswaldense, these are clustered mostly within a large conserved genomic magnetosome island (MAI) comprising the mms6, mamGFDC, mamAB, and mamXY operons. Here, we demon...
Article
Full-text available
The synthetic production of monodisperse single magnetic domain nanoparticles at ambient temperature is challenging. In nature, magnetosomes-membrane-bound magnetic nanocrystals with unprecedented magnetic properties-can be biomineralized by magnetotactic bacteria. However, these microbes are difficult to handle. Expression of the underlying biosyn...
Article
[1] Magnetotactic bacteria contain chains of magnetically interacting crystals (magnetosomes), which aid navigation (magnetotaxis). To improve the efficiency of magnetotaxis, magnetosome crystals (which can consist of magnetite or greigite) should be magnetically stable single domain (SD) particles. Larger particles subdivide into nonuniform multid...
Article
Full-text available
Magnetotactic bacteria (MTB) biomineralize magnetosomes, nano-scale crystals of magnetite or greigite in membrane enclosures that comprise a permanent magnetic dipole in each cell. MTB control the mineral composition, habit, size, and crystallographic orientation of the magnetosomes, as well as their arrangement within the cell. Studies involving m...
Data
Full-text available
Materials providing additional crystallographic information on orientation relationships of observed twin boundaries, stacking faults and epitaxial layers in magnetite and maghemite nanocrystals, based on FFT analysis and nano-diffraction data
Article
Full-text available
The origin of growth defects and epitaxial layers in nanocrystalline magnetite (Fe3O4) and its oxidation product, maghemite (gamma-Fe2O3), was studied. In magnetite, two types of planar defects are identified, (111) spinel-law twin boundaries and (110) stacking faults (SF). The twinning in magnetite is related to magnetic-field-assisted self-assemb...
Article
Magnetospirillum gryphiswaldense uses intracellular chains of membrane-enveloped magnetite crystals, the magnetosomes, to navigate within magnetic fields. The biomineralization of magnetite nanocrystals requires several magnetosome-associated proteins, whose precise functions so far have remained mostly unknown. Here, we analysed the functions of M...