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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2022 - 20233
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Start date: 2010 × Subject: 66 ×

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Now showing 1 - 3 of 3
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    Biorecovery of rare earth elements from fluorescent lamp powder using the fungus Aspergillus niger in batch and semicontinuous systems
    (Minerals Engineering, 2023) Castro Ruiz, Laura; Gómez-Álvarez, Helena; González González, Felisa; Muñoz Sánchez, Jesús Ángel
    Rare earth elements (REE) are essential in the manufacture of high-technology goods. Tons of wastes containing REE are yearly accumulated; however, environmentally friendly recycling methods are poorly studied. The use of heterotrophic microorganisms could be particularly relevant in the bioleaching of wastes transforming insoluble REE-bearing compounds into more soluble forms which are directly and/or indirectly involved in their metabolism. In this study, bioleaching of rare earth elements from fluorescent phosphor powder in fluorescent tubes using Aspergillus niger CECT2807 was investigated. Bioleaching experiments were performed in batch cultures at 1% pulp density. The concentrations in solution reached 122 mg/l of Y, 8.50 mg/l of Eu, 0.95 mg/l of Ce, 0.40 mg/l of Tb and 1.11 mg/l of La, after 7 days. Then, REE precipitated due to the generation of oxalic acid by the fungus. The residues generated were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) and the lamp powder biotransformation was evidenced. Additionally, semicontinuous experiments were conducted and evidenced significant increase of REE dissolution rate in static conditions. The amount of extracted REE under static conditions reached 16.5 mg of Y and 0.75 mg of Eu per gram of fluorescent lamp powder.
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    Enhancing tellurite and selenite bioconversions by overexpressing a methyltransferase from Aromatoleum sp. CIB
    (Microbial Biotechnology, 2022) Alonso‐Fernandes, Elena; Fernández‐Llamosas, Helga; Cano, Irene; Serrano‐Pelejero, Cristina; Castro Ruiz, Laura; Díaz, Eduardo; Carmona, Manuel
    Pollution by metalloids, e.g., tellurite and selenite, is of serious environmental concern and, therefore, there is an increasing interest in searching for ecologically friendly solutions for their elimination. Some microorganisms are able to reduce toxic tellurite/selenite into less toxic elemental tellurium (Te) and selenium (Se). Here, we describe the use of the environmentally relevant β‐proteobacterium Aromatoleum sp. CIB as a platform for tellurite elimination. Aromatoleum sp. CIB was shown to tolerate 0.2 and 0.5 mM tellurite at aerobic and anaerobic conditions, respectively. Furthermore, the CIB strain was able to reduce tellurite into elemental Te producing rod‐shaped Te nanoparticles (TeNPs) of around 200 nm length. A search in the genome of Aromatoleum sp. CIB revealed the presence of a gene, AzCIB_0135, which encodes a new methyltransferase that methylates tellurite and also selenite. AzCIB_0135 orthologs are widely distributed in bacterial genomes. The overexpression of the AzCIB_0135 gene both in Escherichia coli and Aromatoleum sp. CIB speeds up tellurite and selenite removal, and it enhances the production of rod‐shaped TeNPs and spherical Se nanoparticles (SeNPs), respectively. Thus, the overexpression of a methylase becomes a new genetic strategy to optimize bacterial catalysts for tellurite/selenite bioremediation and for the programmed biosynthesis of metallic nanoparticles of biotechnological interest.
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    Transcriptional response of the xerotolerant Arthrobacter sp. Helios strain to PEG-induced drought stress
    (Frontiers in Microbiology, 2022) Hernández-Fernández, Gabriel; Galán, Beatriz; Carmona, Manuel; Castro Ruiz, Laura; García, José Luis
    A new bacterial strain has been isolated from the microbiome of solar panels and classified as Arthrobacter sp. Helios according to its 16S rDNA, positioning it in the “Arthrobacter citreus group.” The isolated strain is highly tolerant to desiccation, UV radiation and to the presence of metals and metalloids, while it is motile and capable of growing in a variety of carbon sources. These characteristics, together with observation that Arthrobacter sp. Helios seems to be permanently prepared to handle the desiccation stress, make it very versatile and give it a great potential to use it as a biotechnological chassis. The new strain genome has been sequenced and its analysis revealed that it is extremely well poised to respond to environmental stresses. We have analyzed the transcriptional response of this strain to PEG6000-mediated arid stress to investigate the desiccation resistance mechanism. Most of the induced genes participate in cellular homeostasis such as ion and osmolyte transport and iron scavenging. Moreover, the greatest induction has been found in a gene cluster responsible for biogenic amine catabolism, suggesting their involvement in the desiccation resistance mechanism in this bacterium.