biomineralization Dotaz Zobrazit nápovědu
Biomineralization means mineral formation under the influence of organisms. Sulphate-reducing bacteria (SRB) constitute an essential role of iron sulphide minerals precipitation. Their composition involves amorphous, non-stoichiometric or crystalline iron sulphides, weakly or strongly magnetic. Variation in environmental conditions can alter the reactive iron species within the mineral, potentially modifying their magnetic properties. Biogenic iron sulphide minerals can be used as heavy metals and toxic ions adsorbents in soil or water remediation. For these reasons, a series of laboratory-scale iron sulphide synthesis experiments with the aim to study the chemical composition, mineralogy and magnetic properties of iron sulphide precipitates were carried out using SRB under various cultivation mode and nutrient medium composition. Energy-dispersive X-ray analysis (EDX) showed formation of iron sulphides in all biogenic samples and iron phosphates in abiotic controls. Results of X-ray diffraction analysis (XRD) in biomineralized samples confirmed nanocrystalline greigite, mackinawite and sulphur alpha. Magnetic measurements showed that sample prepared by static cultivation without addition of fresh nutrient medium was the most magnetic, magnetic hysteresis of sample formed under semicontinuous mode without any nutrient supply was the lowest. Abiotic samples contained only vivianite and they did not prove any significant response to magnetic field.
Aortic stenosis is one of the most common heart diseases that occur in developed countries. The disease has many causes; among the most discussed is excessive intake of fluorides. The aim of our work is to clarify the biochemical nature of biomineralizations in cardial tissue as well as to select an appropriate medication and to mitigate the disease. Peptide mapping combined with UHPLC and MS were used in the study of the mineralized cardial tissue. We managed to identify proteins such as alkaline phosphatase, biglycan, mimecan, osteopontin, periostin and proteoglycan, which are probably related to mineralization of the valves.
- MeSH
- aortální stenóza * etiologie MeSH
- chromatografie kapalinová využití MeSH
- fluor škodlivé účinky MeSH
- hmotnostní spektrometrie * metody přístrojové vybavení využití MeSH
- kalcinóza * patofyziologie MeSH
- lidé MeSH
- peptidové mapování * metody trendy využití MeSH
- tandemová hmotnostní spektrometrie využití MeSH
- vitamin K chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
Autor popisuje případ patologické mineralizace zadní komory oka. Histologické vyšetření obalů postiženého oka odhalilo zánět, otok, poruchy cirkulace a známky dystrofické kalcifikace. Strukturálně fázové vyšetření a chemická analýza kalcifikace stanovily, že biominerál je tvořen hydroxyapatitem z relativně malých krystalů s poruchou krystalické mřížky. V popisovaném případě byla tvorba patologického biominerálu ve zrakovém orgánu vyvolána penetrujícím poraněním. Oční úraz mohl způsobit hemoftalmus a chronickou zánětlivou reakci v obalech oka. Tyto procesy mohly způsobit částečnou atrofii oka a vývoj dystrofických a nekrobiotických změn v tkáních. Patologická biomineralizace v postiženém oku se vznikla jako druh dystrofické kalcifikace. Klíčová slova: oko, patologická biomineralizace, hydroxyapatit Do redakce doručeno dne 23. 4. 2014 Do tisku přijato dne 18. 7. 2014
The authors have described the case of pathological biomineralization of ocular posterior chamber. Histological examination of affected eye shells revealed inflammation, oedema, dyscirculatory violations, and signs of dystrophic calcification. Structural-phase and chemical analyses of calcification have revealed that the biomineral consists of hydroxyapatite with relatively small crystallite size and defective crystal lattice. In the described case the formation of pathological biomineral in the vision organ was initiated by penetrating wound. Eye injury might have caused a hemophthalmus and chronic inflammatory reaction in the shells, these processes eventually led to the organ subatrophy and to the development of dystrophic and necrobiotic changes in the tissues. Pathological biomineralization in the affected organ developed as a type of dystrophic calcification. Key words: eye, pathological biomineralization, hydroxyapatite
- Klíčová slova
- patologická biomineralizace,
- MeSH
- heterotopická osifikace diagnóza etiologie patofyziologie MeSH
- hydroxyapatit * izolace a purifikace MeSH
- kalcinóza * diagnóza etiologie patofyziologie MeSH
- lidé středního věku MeSH
- lidé MeSH
- mikroanalýza elektronovou sondou MeSH
- oči patologie MeSH
- oční nemoci * diagnóza patofyziologie patologie MeSH
- penetrující poranění oka komplikace MeSH
- transmisní elektronová mikroskopie MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- kazuistiky MeSH
Current studies reveal that the biomineralization of U(VI) by anaerobes normally produces nano-sized U(IV) minerals that can easily re-migrate/re-oxidize, while the biomineralization of U(VI) by aerobes has been constrained because the general mechanism has not yet been fully characterized. The biomineralization of U(VI) by Bacillus cereus 12-2 was investigated in this work. The maximum biosorption capability of intact cells was 448.68 mg U/g biomass (dry weight) at pH 5, while a decrease over 60% was induced when phosphate, amino, and especially carboxyl groups were shielded. X-ray diffraction, electron microscopy, and tracing the concentration of soluble intracellular U(VI) demonstrated that extracellular amorphous uranium particles can directly enter cells as solid, and about 10 nm-sized (NH4)(UO2)PO4·3H2O was formed subsequently. It was also revealed that the biosorption capability was not affected by a high uranium concentration, while biomineralization was inhibited, suggesting that a high concentration of heavy metals may inhibit the enzyme activity involved in biomineralization. Besides, U(VI) could trigger the overexpression of proteins with a molecular weight of 22 kD, including various phosphatases, kinases, and other enzymes that are related to metabolism and stimulus response, which may contribute to the intracellular transformation of U(VI) compounds from amorphous to crystalline phase. Taken together, the immobilization of U(VI) by B. cereus 12-2 contains two major steps: (1) fast immobilization of U(VI) on the cell surface as amorphous compounds, in which the carboxyl groups served as the predominant coordination functional groups and (2) transport of amorphous particles to cells directly and enzyme-related formation of uramphite.
- MeSH
- Bacillus cereus chemie MeSH
- difrakce rentgenového záření metody MeSH
- minerály chemie MeSH
- uran chemie MeSH
- Publikační typ
- časopisecké články MeSH
The remediation of Pb(II) through biomineralization is rergarded as a promising technique as well as an interesting phenomenon for transforming heavy metals from mobile species into very stable minerals in the environment. Studies are well needed for in-depth understanding the mechanism of Pb(II) immobilized by bacteria. In the present study, we investigated the uptake and biomineralization of Pb(II) using Bacillus cereus 12-2 isolated from lead-zinc mine tailings. The maximum Pb(II) uptake capacity of B. cereus 12-2 was 340 mg/g at pH 3.0. Zeta potential analyses and selective passivation experiments demonstrated that electrostatic attraction was the main force driving the uptake of Pb(II), while the carboxyl, amide and phosphate functional groups of the bacteria provided the binding sites for immobilizing Pb(II). XRD and TEM investigation revealed that the Pb(II) loaded on bacteria could be stepwise transformed into rod-shaped Ca2.5Pb7.5(OH)2(PO4)6 nanocrystal. Combined with protein denaturalization experiments, we proposed that the biomineralization of Pb(II) possibly consisted of two steps: (1) Rapid biosorption of Pb(II) on B. cereus 12-2 through the synergy of electrostatic attraction, ionic exchange and chelating activity of functional groups; (2) enzyme-mediated mineral transformation from amorphous precipitate to rod-shaped crystalline minerals happening gradually inside the bacteria.
- MeSH
- biologie MeSH
- biomechanika MeSH
- kongresy jako téma MeSH
- minerály MeSH
- Publikační typ
- zprávy MeSH
Biphasic calcium phosphate (BCP) scaffolds were successfully produced by robocasting. The BCP powder was prepared by hydrothermal synthesis (150°C for 4 h) and calcined at 1000°C. The as-obtained powder was milled to obtain A suitable particle size distribution (PSD) for optimizing the rheological properties of the suspensions and pastes prepared thereof. Scaffolds with different pore dimensions (300x300, 500x500, 250x500 and 300x600 μm) were prepared by extruding the pastes through 410 μm diameter nozzles. The green scaffolds were dried and posteriorly sintered at 1100°C. The compressive strength of the sintered scaffolds was well within the range of the mechanical properties reported from cancellous bone, being intrinsically related with the particle size distribution. Moreover, the obtained scaffolds demonstrated to have good biomineralization ability. The obtained scaffolds by robocasting revealed to possess promising features for their applications in bone regeneration and tissue engineering.
Sequestration of arsenic to biogenic sulfide minerals is known from As-contaminated anoxic environments. Despite numerous successful laboratory experiments, the process remains difficult to predict in moderate arsenic conditions. We performed microcosm experiments using naturally contaminated groundwater (containing ca. 6 mg/L As) and natural organic matter (NOM) particles both collected from wetland soil. Macroscopic realgar precipitates, occasionally accompanied by bonazziite, a FeS phase, elementary S, calcite, and whewellite, appeared after 4 to 18 months. Realgar only precipitated in microcosms moderately poisoned by azide or antibiotics and those in which oxidation of hydrogen sulfide to sulfur took place. The biomineralization process was not affected by the presence of additional carbon sources or the diversity, community structure, and functional composition of the microbial community. Hydrogen sulfide concentration was greater in the realgar-free microcosms, suggesting that arsenic thiolation prevented precipitation of realgar. We compared our data to available microbial community data from soils with different rates of realgar precipitation, and found that the communities from realgar-encrusted NOM particles usually showed limited sulfate reduction and the presence of fermentative metabolisms, whereas communities from realgar-free NOM particles were strongly dominated by sulfate reducers. We argue that the limited sulfate supply and intensive fermentation amplify reducing conditions, which make arsenic sulfide precipitation plausible in high-sulfate, low-arsenic groundwaters.
- MeSH
- arsenikové přípravky analýza MeSH
- biomineralizace * MeSH
- chemické látky znečišťující vodu analýza MeSH
- huminové látky analýza MeSH
- mikrobiota * MeSH
- mokřady MeSH
- oxidace-redukce MeSH
- podzemní voda chemie mikrobiologie MeSH
- půda chemie MeSH
- sírany chemie MeSH
- sulfidy analýza MeSH
- teoretické modely MeSH
- Publikační typ
- časopisecké články MeSH
- Klíčová slova
- bioaktivní sklo, fluoroapatit,
- MeSH
- biomineralizace MeSH
- citlivost dentinu * epidemiologie terapie MeSH
- fluoridy analýza farmakologie terapeutické užití MeSH
- inzerce jako téma MeSH
- lidé MeSH
- průzkumy a dotazníky MeSH
- zubní pasty * farmakologie terapeutické užití MeSH
- zvracení MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- klinická studie MeSH
