Laszlo J. Csetenyi

Biomineralization of metal carbonates by Neurospora crassa.

In this research, the urease-positive fungus Neurospora crassa was investigated for the biomineralization of calcium carbonate and its potential application in metal biorecovery and/or bioremediation. After 12 d incubation at 25 °C in urea and calcium-containing medium, extensive biomineralization of fungal filaments was observed. Energy dispersive X-ray analysis of crystalline precipitates on the hyphae of N. crassa showed that the main elements present in the crystals were Ca, C, and O. X-ray diffraction (XRD) of the precipitates showed they were composed solely of calcite (CaCO3) and over 90% Ca could be removed from the media by the fungal biomass and associated calcite precipitation. To further investigate biologically induced metal carbonate biomineralization, CdCl2 was contacted with supernatants of N. crassa obtained after growth in urea-containing medium. XRD showed that the Cd(2+) was precipitated as pure otavite (CdCO3) with a particle size range of 55 to 870 nm, and approximately 1.5% having nanoscale dimensions. These results provide direct experimental evidence for the precipitation of metal carbonates such as calcite and otavite based on biologically induced mineralization, and suggest that urease-positive fungi may play a potential role in the synthesis of novel biominerals and in metal bioremediation or biorecovery.

Fungal Biomineralization of Manganese as a Novel Source of Electrochemical Materials

Electrical energy storage systems such as rechargeable lithium-ion batteries (LiBs) and supercapacitors have shown great promise as sustainable energy storage systems [1-4]. However, LiBs have high specific energy density (energy stored per unit mass) and act as slow, steady suppliers for large energy demands. In contrast, supercapacitors possess high specific power (energy transferred per unit mass per unit time) and can charge and discharge quickly for low energy demands. In LiBs, graphite is the most common anode material, although high electrolyte sensitivity and low charge capacity can limit performance. Efforts have been made to improve LiB or supercapacitor performance using alternative electrode materials such as carbon nanotubes and manganese oxides (MnxOy) [3, 5-14]. Microorganisms play significant roles in metal and mineral biotransformations [15-22]. Fungi possess various biomineralization properties, as well as a filamentous mycelium, which may provide mechanical support for mineral deposition. Although some research has been carried out on the application of biological materials as carbon precursors [8, 9, 23], biomineralizing fungal systems have not been investigated. In this research, novel electrochemical materials have been synthesized using a fungal Mn biomineralization process based on urease-mediated Mn carbonate bioprecipitation [24]. The carbonized fungal biomass-mineral composite (MycMnOx/C) showed a high specific capacitance (>350 F g(-1)) in a supercapacitor and excellent cycling stability (>90% capacity was retained after 200 cycles) in LiBs. This is the first demonstration of the synthesis of electrode materials using a fungal biomineralization process, thus providing a novel strategy for the preparation of sustainable electrochemical materials.

Uranium bioprecipitation mediated by yeasts utilizing organic phosphorus substrates.

In this research, we have demonstrated the ability of several yeast species to mediate U(VI) biomineralization through uranium phosphate biomineral formation when utilizing an organic source of phosphorus (glycerol 2-phosphate disodium salt hydrate (C3H7Na2O6P·xH2O (G2P)) or phytic acid sodium salt hydrate (C6H18O24P6·xNa+·yH2O (PyA))) in the presence of soluble UO2(NO3)2. The formation of meta-ankoleite (K2(UO2)2(PO4)2·6(H2O)), chernikovite ((H3O)2(UO2)2(PO4)2·6(H2O)), bassetite (Fe++(UO2)2(PO4)2·8(H2O)), and uramphite ((NH4)(UO2)(PO4)·3(H2O)) on cell surfaces was confirmed by X-ray diffraction in yeasts grown in a defined liquid medium amended with uranium and an organic phosphorus source, as well as in yeasts pre-grown in organic phosphorus-containing media and then subsequently exposed to UO2(NO3)2. The resulting minerals depended on the yeast species as well as physico-chemical conditions. The results obtained in this study demonstrate that phosphatase-mediated uranium biomineralization can occur in yeasts supplied with an organic phosphate substrate as sole source of phosphorus. Further understanding of yeast interactions with uranium may be relevant to development of potential treatment methods for uranium waste and utilization of organic phosphate sources and for prediction of microbial impacts on the fate of uranium in the environment.

Lead Bioprecipitation by Yeasts Utilizing Organic Phosphorus Substrates

ABSTRACT Yeasts can exhibit various mechanisms that effect changes in metal speciation, toxicity and mobility. This research has examined the role of yeast phosphatases in lead bioprecipitation when utilizing an organic phosphorus-containing substrate as the sole phosphorus source. The formation of lead-containing biominerals after growth with organic phosphorus sources (glycerol 2-phosphate, phytic acid) was demonstrated and it was found that test yeasts were capable of mediating precipitation of lead phosphate (Pb3(PO4)2), pyromorphite (Pb5(PO4)3Cl), anglesite (PbSO4), and the lead oxides massicot and litharge (PbO), with variations in the mineral types produced between the different species. All test yeasts produced pyromorphite, and most produced anglesite. Lead oxides were only detected with Pichia acacia. Lead-containing precipitates were also formed if yeast cells were pre-grown in organic-phosphorus-containing media and subsequently exposed to Pb(NO3)2. The role of phosphatases in mediating the formation of lead-containing minerals has provided further understanding of potential fungal roles in metal and mineral biogeochemistry as well as the possible significance of these mechanisms for element biorecovery or bioremediation.

Recycling of dimension limestone industry waste in concrete

Abstract Extractive and mining operations are one of the largest waste producing streams in the world. In general, mining operation is accompanied with the production of stone and slurry wastes. Such wastes occupy large land near the mining area and the fine slurry particles cause bronchial, vision and skin disorders in the nearby inhabitants. Present study examines the suitability of using dimension limestone waste as fine aggregate in concrete. Twenty-six concrete mixes were examined by replacing river sand fine aggregate with crushed sand, slurry and manufactured sand (MS). Test results indicated that MS formulated by blending crushed solid stone waste (85%) and slurry (15%) can be used as fine aggregate in concrete. Concrete cast with MS demonstrated superior strength and reduced bleeding, permeability and void formation within the concrete. The use of MS will contribute to bulk utilisation of waste as it can completely replace river sand in concrete, hence, promoting sustainable development in the region by consuming both types of stone waste in significant quantities.

Sulfuric Acid Resistance of Quartz Sandstone Aggregate Concrete

AbstractSandstone is a popular type of natural stone and is made up of collective grains of quartz. India is one of the countries blessed with various types of sandstones with appealing colors. Dem...

Utilising Fine and Coarse Recycled Aggregates from the Gulf Region in Concrete

This paper explores the feasibility in utilising materials generated from C&DW to produce a ‘green’ concrete. The two materials that are considered here are, (i) up-sizing silt-size material generated from recycled aggregates to produce a synthetic silt-sand and (ii) processed recycled coarse aggregates (RA) sourced from a Gulf Region landfill site. The work has demonstrated that there is potential for utilising silt wastes into foamed concrete, which can then be crushed to a sand-sized material suitable for use in concrete, however the porous nature of the material has highlighted that the water demand of this RA is high. RAs were characterised to BS EN 12620 and found suitable for use in concrete. The effect of RA on concrete properties is minimal when used up to 35% replacement levels, provided that they are pre-soaked.