Person:
Castro Ruiz, Laura

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First Name
Laura
Last Name
Castro Ruiz
URI
https://hdl.handle.net/20.500.14352/81200
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Ciencias Químicas
Department
Ingeniería Química y de Materiales
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2020 - 20213
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Start date: 2020 × Subject: 577.1 ×

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Now showing 1 - 3 of 3
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    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 Luisa
    Tellurium 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.
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    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, Laura
    The 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.
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    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 Ángel
    Rare 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.