Person: Castro Ruiz, Laura
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First Name
Laura
Last Name
Castro Ruiz
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Ingeniería Química y de Materiales
Area
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6 results
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Item Green synthesis of tellurium nanoparticles by tellurate and tellurite reduction using Aeromonas hydrophila under different aeration conditions(Hydrometallurgy, 2020) Castro Ruiz, Laura; Li, Jing; González González, Felisa; Muñoz Sánchez, Jesús Ángel; Blázquez Izquierdo, María LuisaTellurium nanoparticles (TeNPs) are extensively used in biomedicine, electronics and some other industrial applications. Few microorganisms have been studied for the production of TeNPs either under aerobic or anaerobic conditions. Remarkably, this study is the first report of a bacteria able to perfectly grow anaerobically and aerobically in the presence of both tellurium oxyanions, TeO32− and TeO42−. Aeromonas hydrophila offers a clean and cost-effective synthesis of tellurium nanoparticles using a biological method and overcoming the main limitations of traditional synthesis, such as the requirement of a lot of energy and toxic reagents. The cells grew up to 75 mg/L of tellurium when tellurite was the precursor and up to 200 mg/L of tellurium with tellurate. The biogenic nanoparticles were extensively characterized in terms of morphology, structure and composition using SEM, TEM, XRD and EDX analysis. Different Te(0) nanostructures were biosynthesized varying growth conditions: crystalline nanorods (some of them reach more than 1000 nm in length due to Ostwald ripening), rosettes and irregularly shaped nanospheres. In addition, A. hydrophila developed various mechanisms to produce the elemental tellurium and to overcome the toxicity demonstrating the versatility of this microorganism to subsist in polluted environments and its potential for biotechnological applications in bioremediation including the green synthesis of TeNPs.Item Biosorption of Zn(II) from industrial effluents using sugar beet pulp and F . vesiculosus : From laboratory tests to a pilot approach(Science of Total Environment, 2017) Castro Ruiz, Laura; Blázquez Izquierdo, María Luisa; González González, Felisa; Muñoz Sánchez, Jesús Ángel; Ballester Pérez, AntonioThe aim of this work was to demonstrate the feasibility of the application of biosorption in the treatment of metal polluted wastewaters through the development of several pilot plants to be implemented by the industry. The use as biosorbents of both the brown seaweed Fucus vesiculosus and a sugar beet pulp was investigated to remove heavy metal ions from a wastewater generated in an electroplating industry: Industrial Goñabe (Valladolid, Spain). Batch experiments were performed to study the effects of pH, contact time and initial metal concentration on metal biosorption. It was observed that the adsorption capacity of the biosorbents strongly depended on the pH, increasing as the pH rises from 2 to 5. The adsorption kinetic was studied using three models: pseudo first order, pseudo second order and Elovich models. The experimental data were fitted to Langmuir and Freundlich isotherm models and the brown alga F. vesiculosus showed higher metal uptake than the sugar beet pulp. The biomasses were also used for zinc removal in fixed-bed columns. The performance of the system was evaluated in different experimental conditions. The mixture of the two biomasses, the use of serial columns and the inverse flow can be interesting attempts to improve the biosorption process for large-scale applications.Item Xerotolerance: a new property in Exiguobacterium Genus(Microorganisms, 2021) Castillo López, María; Galán, Beatriz; Carmona, Manuel; Navarro Llorens, Juana María; Peretó, Juli; Porcar, Manuel; Getino, Luis; Olivera, Elías R.; Luengo, José M.; García, José Luis; Castro Ruiz, LauraThe highly xerotolerant bacterium classified as Exiguobacterium sp. Helios isolated from a solar panel in Spain showed a close relationship to Exiguobacterium sibiricum 255-15 isolated from Siberian permafrost. Xerotolerance has not been previously described as a characteristic of the extremely diverse Exiguobacterium genus, but both strains Helios and 255-15 showed higher xerotolerance than that described in the reference xerotolerant model strain Deinococcus radiodurans. Significant changes observed in the cell morphology after their desiccation suggests that the structure of cellular surface plays an important role in xerotolerance. Apart from its remarkable resistance to desiccation, Exiguobacterium sp. Helios strain shows several polyextremophilic characteristics that make it a promising chassis for biotechnological applications. Exiguobacterium sp. Helios cells produce nanoparticles of selenium in the presence of selenite linked to its resistance mechanism. Using the Lactobacillus plasmid pRCR12 that harbors a cherry marker, we have developed a transformation protocol for Exiguobacterium sp. Helios strain, being the first time that a bacterium of Exiguobacterium genus has been genetically modified. The comparison of Exiguobacterium sp. Helios and E. sibiricum 255-15 genomes revealed several interesting similarities and differences. Both strains contain a complete set of competence-related DNA transformation genes, suggesting that they might have natural competence, and an incomplete set of genes involved in sporulation; moreover, these strains not produce spores, suggesting that these genes might be involved in xerotolerance.Item Bioleaching of Phosphate Minerals Using Aspergillus niger: Recovery of Copper and Rare Earth Elements(Metals, 2020) Castro Ruiz, Laura; Blázquez Izquierdo, María Luisa; González González, Felisa; Muñoz Sánchez, Jesús ÁngelRare earth elements (REE) are essential in high-technology and environmental applications, where their importance and demand have grown enormously over the past decades. Many lanthanide and actinide minerals in nature are phosphates. Minerals like monazite occur in small concentrations in common rocks that resist weathering. Turquoise is a hydrous phosphate of copper and aluminum scarcely studied as copper ore. Phosphate-solubilizing microorganisms are able to transform insoluble phosphate into a more soluble form which directly and/or indirectly contributes to their metabolism. In this study, bioleaching of heavy metals from phosphate minerals by using the fungus Aspergillus niger was investigated. Bioleaching experiments were examined in batch cultures with different mineral phosphates: aluminum phosphate (commercial), turquoise, and monazite (natural minerals). The experiments were performed at 1% pulp density and the phosphorous leaching yield was aluminum phosphate > turquoise > monazite. Bioleaching experiments with turquoise showed that A. niger was able to reach 8.81 mg/l of copper in the aqueous phase. Furthermore, the fungus dissolved the aluminum cerium phosphate hydroxide in monazite, reaching up to 1.37 mg/L of REE when the fungus was grown with the mineral as the sole phosphorous source. Furthermore, A. niger is involved in the formation of secondary minerals, such as copper and REE oxalates.Item Biosynthesis of selenium nanoparticles by Azoarcus sp. CIB(Microbial Cell Factories, 2016) Fernández-Llamosas, Helga; Castro Ruiz, Laura; Blázquez Izquierdo, María Luisa; Díaz, Eduardo; Carmona, ManuelBackground: Different bacteria have been reported so far that link selenite resistance to the production of metallic selenium nanoparticles (SeNPs). Although SeNPs have many biotechnological applications in diverse areas, the molecular mechanisms involved in their microbial genesis are not fully understood. The Azoarcus genus is a physiologically versatile group of beta-proteobacteria of great environmental relevance. Azoarcus sp. CIB is a facultative anaerobe that combines the ability to degrade under aerobic and/or anaerobic conditions a wide range of aromatic compounds, including some toxic hydrocarbons such as toluene and m-xylene, with an endophytic life style in the root of rice. We unravel here an additional physiological feature of the strain CIB that is related to its resistance to selenium oxyanions and the formation of SeNPs. Results: This work is the first report of a member of the Azoarcus genus that is able to anaerobically grow in the presence of selenite. Electron microscopy preparations and X-ray spectroscopy analyses demonstrate the reduction of selenite to spherical electron-dense SeNPs whose average size was 123 ± 35 nm of diameter. Our data suggest that the main molecular mechanism of selenite resistance resides on an energy-dependent selenite exporter. Azoarcus cells trigger the synthesis of SeNPs when they reach the stationary-phase of growth, and either the exhaustion of electron donor or acceptor, both of which lead to starvation conditions, produce the reduction of selenite to red elemental selenium. Azoarcus becomes a promising biocatalyst, either as whole cells or cellular extracts, for the anaerobic and/or aerobic green synthesis of SeNPs. Conclusions: Azoarcus turns out to be a new eco-friendly system to reduce selenite and produce spherical SeNPs. Moreover, this is the first report of a rice endophyte able to produce SeNPs. Since Azoarcus is also able to degrade both aerobically and anaerobically toxic aromatic compounds of great environmental concern, it becomes a suitable candidate for a more sustainable agricultural practice and for bioremediation strategies.Item Exploring the Possibilities of Biological Fabrication of Gold Nanostructures Using Orange Peel Extract(Metals, 2015) Castro Ruiz, Laura; Blázquez Izquierdo, María Luisa; González González, Felisa; Muñoz Sánchez, Jesús Ángel; Ballester Pérez, AntonioDevelopment of nanotechnology requires a constant innovation and improvement in many materials. The exploration of natural resources is a promising eco-friendly alternative for physical and chemical methods. In the present work, colloidal gold nanostructures were prepared using orange peel extract as a stabilizing and reducing agent. The initial pH value of the solution and the concentration of the gold precursor had an effect on the formation and morphology of nanoparticles. The method developed is environmentally friendly and allows control of nanoparticles. By controlling the pH and, especially, the gold concentration, we are able to synthesize crystalline gold nanowires using orange peel extract in the absence of a surfactant or polymer to direct nanoparticle growth, and without external seeding. UV-VIS spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize the nanoparticles obtained by biosynthesis.