Examinando por Autor "Remonsellez, Francisco"
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Ítem Arsenic Response of Three Altiplanic Exiguobacterium Strains With Different Tolerance Levels Against the Metalloid Species: A Proteomics Study(Frontiers Media S.A., 2019-09) Castro Severyn, Juan; Pardo Esté, Coral; Sulbaran, Yoelvis; Cabezas, Carolina; Gariazzo, Valentina; Briones, Alan; Morales, Naiyulin; Séveno, Martial; Decourcelle, Mathilde; Salvetat, Nicolas; Remonsellez, Francisco; Castro Nallar, Eduardo; Molina, Franck; Molina, Laurence; Saavedra, Claudia P.Exiguobacterium is a polyextremophile bacterial genus with a physiology that allows it to develop in different adverse environments. The Salar de Huasco is one of these environments due to its altitude, atmospheric pressure, solar radiation, temperature variations, pH, salinity, and the presence of toxic compounds such as arsenic. However, the physiological and/or molecular mechanisms that enable them to prosper in these environments have not yet been described. Our research group has isolated several strains of Exiguobacterium genus from different sites of Salar de Huasco, which show different resistance levels to As(III) and As(V). In this work, we compare the protein expression patterns of the three strains in response to arsenic by a proteomic approach; strains were grown in absence of the metalloid and in presence of As(III) and As(V) sublethal concentrations and the protein separation was carried out in 2D electrophoresis gels (2D-GE). In total, 999 spots were detected, between 77 and 173 of which showed significant changes for As(III) among the three strains, and between 90 and 143 for As(V), respectively, compared to the corresponding control condition. Twenty-seven of those were identified by mass spectrometry (MS). Among these identified proteins, the ArsA [ATPase from the As(III) efflux pump] was found to be up-regulated in response to both arsenic conditions in the three strains, as well as the Co-enzyme A disulfide reductase (Cdr) in the two more resistant strains. Interestingly, in this genus the gene that codifies for Cdr is found within the genic context of the ars operon. We suggest that this protein could be restoring antioxidants molecules, necessary for the As(V) reduction. Additionally, among the proteins that change their expression against As, we found several with functions relevant to stress response, e.g., Hpf, LuxS, GLpX, GlnE, and Fur. This study allowed us to shed light into the physiology necessary for these bacteria to be able to tolerate the toxicity and stress generated by the presence of arsenic in their niche. © Copyright © 2019 Castro-Severyn, Pardo-Esté, Sulbaran, Cabezas, Gariazzo, Briones, Morales, Séveno, Decourcelle, Salvetat, Remonsellez, Castro-Nallar, Molina, Molina and Saavedra.Ítem Biochemical, genomic and structural characteristics of the Acr3 pump in Exiguobacterium strains isolated from arsenic-rich Salar de Huasco sediments(Frontiers Media S.A., 2022-11) Castro-Severyn, Juan; Pardo-Esté, Coral; Araya-Durán, Ingrid; Gariazzo, Valentina; Cabezas, Carolina; Valdés, Jorge; Remonsellez, Francisco; Saavedra, Claudia P.Arsenic is a highly toxic metalloid of major concern for public safety. However, microorganisms have several resistance mechanisms, particularly the expression of arsenic pumps is a critical component for bacterial ability to expel it and decrease intracellular toxicity. In this study, we aimed to characterize the biochemical, structural, and genomic characteristics of the Acr3 pump among a group of Exiguobacterium strains isolated from different sites of the arsenic-rich Salar de Huasco (SH) ecosystem. We also determined whether the differences in As(III) resistance levels presented by the strains could be attributed to changes in the sequence or structure of this protein. In this context, we found that based on acr3 sequences the strains isolated from the SH grouped together phylogenetically, even though clustering based on gene sequence identity did not reflect the strain’s geographical origin. Furthermore, we determined the genetic context of the acr3 sequences and found that there are two versions of the organization of acr3 gene clusters, that do not reflect the strain’s origin nor arsenic resistance level. We also contribute to the knowledge regarding structure of the Acr3 protein and its possible implications on the functionality of the pump, finding that although important and conserved components of this family of proteins are present, there are several changes in the amino acidic sequences that may affect the interactions among amino acids in the 3D model, which in fact are evidenced as changes in the structure and residues contacts. Finally, we demonstrated through heterologous expression that the Exiguobacterium Acr3 pump does indeed improve the organisms As resistance level, as evidenced in the complemented E. coli strains. The understanding of arsenic detoxification processes in prokaryotes has vast biotechnological potential and it can also provide a lot of information to understand the processes of evolutionary adaptation. Copyright © 2022 Castro-Severyn, Pardo-Esté, Araya-Durán, Gariazzo, Cabezas, Valdés, Remonsellez and Saavedra.Ítem Characterization and salt response in recurrent halotolerant exiguobacteriumsp. SH31 isolated from sediments of salar de huasco, chilean altiplano(Frontiers Media S.A., 2018-09) Remonsellez, Francisco; Castro-Severyn, Juan; Pardo-Esté, Coral; Aguilar, Pablo; Fortt, Jonathan; Salinas, César; Barahona, Sergio; León, Joice; Fuentes, Bárbara; Areche, Carlos; Hernández, Klaudia L.; Aguayo, Daniel; Saavedra, Claudia P.Poly-extremophiles microorganisms have the capacity to inhabit hostile environments and can survive several adverse conditions that include as variations in temperature, pH, and salinity, high levels UV light and atmospheric pressure, and even the presence of toxic compounds and the formation of reactive oxygen species (ROS). A halotolerant Exiguobacterium strain was isolated from Salar de Huasco (Chilean Altiplano), a well-known shallow lake area with variable salinity levels, little human intervention, and extreme environmental conditions, which makes it ideal for the study of resistant mechanisms and the evolution of adaptations. This bacterial genus has not been extensively studied, although its cosmopolitan location indicates that it has high levels of plasticity and adaptive capacity. However, to date, there are no studies regarding the tolerance and resistance to salinity and osmotic pressure. We set out to characterize the Exiguobacterium sp. SH31 strain and describe its phenotypical and genotypical response to osmotic stress. In this context, as a first step to characterize the response to the SH31 strain to salinity and to establish the bases for a molecular study, we proposed to compare its response under three salt conditions (0, 25, and 50 g/l NaCl). Using different physiology, genomic, and transcriptomic approaches, we determined that the bacterium is able to grow properly in a NaCl concentration of up to 50 g/l; however, the best growth rate was observed at 25 g/l. Although the presence of flagella is not affected by salinity, motility was diminished at 25 g/l NaCl and abolished at 50 g/l. Biofilm formation was induced proportionally with increases in salinity, which was expected. These phenotypic results correlated with the expression of related genes: fliG and fliS Motility); opuBA and putP (transport); glnA, proC, gltA, and gbsA (compatible solutes); ywqC, bdlA, luxS y pgaC (biofilm and stress response); and therefore, we conclude that this strain effectively modifies gene expression and physiology in a differential manner when faced with different concentrations of NaCl and these modifications aid survival. © 2007-2018 Frontiers Media S.A. All Rights Reserved.Ítem Characterization of biofilm formation by Exiguobacterium strains in response to arsenic exposure(PubMed, 2023-12-12) Pavez, Valentina B.; Pacheco, Nicolás; Castro-Severyn, Juan; Pardo-Esté, Coral; Álvarez, Javiera; Zepeda, Phillippi; Krüger, Gabriel; Gallardo, Karem; Melo, Francisco; Vernal, Rolando; Aranda, Carlos; Remonsellez, Francisco; Saavedra, Claudia P.In this work, we characterized the composition, structure, and functional potential for biofilm formation of Exiguobacterium strains isolated from the Salar de Huasco in Chile in the presence of arsenic, an abundant metalloid in the Salar that exists in different oxidation states. Our results showed that the Exiguobacterium strains tested exhibit a significant capacity to form biofilms when exposed to arsenic, which would contribute to their resistance to the metalloid. The results highlight the importance of biofilm formation and the presence of specific resistance mechanisms in the ability of microorganisms to survive and thrive under adverse conditions.Ítem Exploring the Influence of Small-Scale Geographical and Seasonal Variations Over the Microbial Diversity in a Poly-extreme Athalosaline Wetland(Springer, 2023) Pardo-Esté, Coral; Guajardo Leiva, Sergio; Remonsellez, Francisco; Castro-Nallar, Eduardo; Castro-Severyn, Juan; Saavedra, Claudia P.Microorganisms are the most diverse life form on the planet and are critical for maintaining the geochemical cycles, especially in extreme environments. Bacterial communities are dynamic and respond directly to changes in abiotic conditions; among these communities, poly-extremophiles are particularly sensitive to perturbations due to their high specialization. Salar de Huasco is a high-altitude wetland located on the Chilean Altiplano exhibiting several conditions considered extreme for life, including negative water balance, extreme variations in temperature and pH values, high UV radiation, and the presence of various toxic metal(oids). However, previous reports have revealed a diverse bacterial community that has adapted to these conditions, here, we aimed to determine whether microbial community diversity and composition changed in response to geographical and seasonal variations. We found that there are significant differences in diversity, abundance, and composition in bacterial taxa that could be attributed to local geographical and seasonal variations, which in turn, can be associated with microbial traits. In conclusion, in this poly-extreme environment, small-scale changes can trigger significant changes in the microbial communities that maintain basic biogeochemical cycles. Further in depth analysis of microbial functionality and geo-ecological dynamics are necessary to better understand the relationships between seasonal changes and bacterial communities. © 2023, The Author(s).Ítem Genetic characterization of salmonella infantis with multiple drug resistance profiles isolated from a poultry-farm in chile(MDPI, 2021-11) Pardo Esté, Coral; Lorca, Diego; Castro Severyn, Juan; Krüger, Gabriel; Alvarez Thon, Luis; Zepeda, Phillippi; Sulbaran Bracho, Yoelvis; Hidalgo, Alejandro; Tello, Mario; Molina, Franck; Molina, Laurence; Remonsellez, Francisco; Castro Nallar, Eduardo; Saavedra, ClaudiaSalmonella comprises over 2500 serotypes and foodborne contamination associated with this pathogen remains an important health concern worldwide. During the last decade, a shift in serotype prevalence has occurred as traditionally less prevalent serotypes are increasing in frequency of infections, especially those related to poultry meat contamination. S. Infantis is one of the major emerging serotypes, and these strains commonly display antimicrobial resistance and can persist despite cleaning protocols. Thus, this work aimed to isolate S. Infantis strains from a poultry meat farm in Santiago, Chile and to characterize genetic variations present in them. We determined their genomic and phenotypic profiles at different points along the production line. The results indicate that the strains encompass 853 polymorphic sites (core-SNPs) with isolates differing from one another by 0–347 core SNPs, suggesting variation among them; however, we found discrete correlations with the source of the sample in the production line. Furthermore, the pan-genome was composed of 4854 total gene clusters of which 2618 (53.9%) corresponds to the core-genome and only 181 (3.7%) are unique genes (those present in one particular strain). This preliminary analysis will enrich the surveillance of Salmonella, yet further studies are required to assess their evolution and phylogeny. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Ítem Physiological Performance and Biosorption Capacity of Exiguobacterium sp. SH31 Isolated from Poly-Extreme Salar de Huasco in the Chilean Altiplano: A Study on Rare-Earth Element Tolerance(Multidisciplinary Digital Publishing Institute (MDPI), 2024-01) Serrano, Genesis; Fortt, Jonathan; Castro-Severyn, Juan; Castillo, Rodrigo; Saavedra, Claudia; Krüger, Gabriel; Núñez, Claudia; Remonsellez, Francisco; Gallardo, KaremRare-earth elements (REEs) are crucial metals with limited global availability due to their indispensable role in various high-tech industries. As the demand for rare-earth elements continues to rise, there is a pressing need to develop sustainable methods for their recovery from secondary sources. Focusing on Exiguobacterium sp. SH31, this research investigates the impact of La, Eu, Gd, and Sm on its physiological performance and biosorption capacity. Tolerance was assessed at pHpzc from 7 to 8 with up to 1 mM rare-earth element concentrations. This study visualized the production of extracellular polymeric substances using Congo red assays and quantified them with ultraviolet–visible spectroscopy. Attenuated total reflectance Fourier transform infrared spectroscopy characterized the functional groups involved in metal interactions. The SH31 strain displayed significant rare-earth element tolerance, confirmed extracellular polymeric substance (EPS) production under all conditions, and increased production in the presence of Sm. Spectroscopy analysis revealed changes in wavelengths associated with OH and R-COO-, suggesting rare-earth element interactions. SH31 demonstrated efficient metal adsorption, with removal rates exceeding 75% at pHpzc 7 and over 95% at pHpzc 7.5 and 8. The calculated Qmax value for rare-earth element biosorption was approximately 23 mg/g, and Langmuir isotherm models effectively described metal sorption equilibria. Genomic exploration identified genes related to extracellular polymeric substance formation, providing insights into underlying mechanisms. This study presents the first evidence of efficient La, Eu, Gd, and Sm adsorption by SH31, emphasizing its potential significance in rare-earth element recovery. © 2023 by the authors.