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 Speeding up bioproduction of selenium nanoparticles by using Vibrio natriegens as microbial factory(Scientific Reports, 2017) Fernández-Llamosas, Helga; Díaz, Eduardo; Carmona, Manuel; Castro Ruiz, Laura; Blázquez Izquierdo, María LuisaSelenium and selenium nanoparticles (SeNPs) are extensively used in biomedicine, electronics and some other industrial applications. The bioproduction of SeNPs is gaining interest as a green method to manufacture these biotechnologically relevant products. Several microorganisms have been used for the production of SeNPs either under aerobic or anaerobic conditions. Vibrio natriegens is a non-pathogenic fast-growing bacterium, easily cultured in different carbon sources and that has recently been engineered for easy genetic manipulation in the laboratory. Here we report that V. natriegens was able to perfectly grow aerobically in the presence of selenite concentrations up to 15 mM with a significant survival still observed at concentrations as high as 100 mM selenite. Electron microscopy and X-ray spectroscopy analyses demonstrate that V. natriegens cells growing aerobically in selenite-containing LB medium at 30 °C produced spherical electron-dense SeNPs whose size ranged from 100–400 nm. Selenite reduction just started at the beginning of the exponential growth phase and the release of SeNPs was observed after cell lysis. Remarkably, V. natriegens produced SeNPs faster than other described microorganisms that were proposed as model bioreactors for SeNPs production. Thus, the fast-growing V. natriegens bacterium becomes a suitable biocatalyst for bioremediation of selenite and for speeding-up the eco-friendly synthesis of SeNPs.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 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 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, ManuelPollution 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.Item 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 LuisA 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.Item Influence of biosurfactants in the recovery of REE from monazite using Burkholderia thailandensis(Hydrometallurgy, 2023) Castro Ruiz, Laura; Gómez-Álvarez, Helena; Carmona, Manuel; Muñoz Sánchez, Jesús Ángel; González González, FelisaThe demand of rare earth elements (REE) has grown over the past decades due to their importance in high technology devices such as wind turbines, superconductors, rechargeable batteries, autocatalytic converters, magnets, or LED lighting. The development of clean mining processes is gaining interest and the biomining of REE is mainly focused on monazite using phosphate solubilizing microorganisms. The members of the genus Burkholderia can dissolve phosphorous from inorganic rocks. Furthermore, several species of Burkholderia are able to produce biosurfactants named rhamnolipids. Nevertheless, rhamnolipid interactions with REE have been poorly investigated. The aim of the present work is the study of the solubilization of monazite and the recovery of REE using the bacterium Burkholderia thailandensis, and the influence of the rhamnolipids produced by the bacteria in the REE mobilization. B. thailandensis grown in nutrient broth with 1% monazite (w/v) reached 8.3 mg·l−1 REE after 15 days. To produce rhamnolipids, B. thailandensis was grown in medium supplemented with 10% glycerol and the biosurfactants were extracted. The critical micelle concentration (CMC) was determined: 94.45 mg·l−1 for commercial rhamnolipids and 60.41 mg·l−1 for purified rhamnolipids. The maximum REE solubilization was obtained at CMC reaching 9.36 mg·l−1 with commercial rhamnolipids and 5.13 mg·l−1 with rhamnolipids produced by B. thailandensis E264.