Examinando por Autor "Saavedra, Claudia P."
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Ítem Adaptive signatures of emerging Salmonella serotypes in response to stressful conditions in the poultry industry(LWT, Volume 2151 January 2025 Article number 117188, 2025) Krüger, Gabriel I.; Pardo-Esté, Coral; Álvarez, Javiera; Pacheco, Nicolás; Castro-Severyn, Juan; Alvarez-Thon, Luis; Saavedra, Claudia P.Salmonella, a zoonotic pathogen, is commonly transmitted through contaminated animal products. This bacterium is emerging in poultry production, often exhibiting multidrug resistance (MDR) and high virulence. Understanding the adaptive mechanisms that allow Salmonella to survive in hostile environments and become virulent is crucial for preventing outbreaks that threaten both the industry and public health. This study uses machine learning to identify adaptive genomic signatures in Salmonella isolates from the poultry industry, focusing on responses to environmental stressors. Significant genomic modifications were found in functions like membrane and cell wall biogenesis, amino acid metabolism, and inorganic ion metabolism, including genes related to antibiotic resistance and virulence. The machine learning model demonstrated high precision (0.980) and accuracy (0.954) in classifying isolates based on their genomic characteristics, with an Area Under the Receiver Operating Characteristic Curve (AUROC) of 0.98. The model identified Salmonella Infantis as one of the most stress-resistant serovars in the poultry industry. The identification of critical genomic sequences underscores the importance of these traits in understanding the bacterium's adaptive mechanisms. These findings underscore the importance of genomic surveillance and advanced bioinformatics to manage emerging pathogens like Salmonella Infantis. © 2024 The AuthorsÍtem Analysis of microbiota-host communication mediated by butyrate in Atlantic salmon(Elsevier, 2023-01) Vargas, Rodrigo A.; Soto-Aguilera, Sarita; Parra, Mick; Herrera, Sebastian; Santibañez, Alvaro; Kossack, Camila; Saavedra, Claudia P.; Mora, Oscar; Pineda, Mauricio; Gonzalez, Oscar; Gonzalez, Alex; Maisey, Kevin; Torres-Maravilla, Edgar; Bermúdez-Humarán, Luis G.; Suárez-Villota, Elkin Y.; Tello, MarioButyrate is a microbiota-produced metabolite, sensed by host short-chain fatty acid receptors FFAR2 (Gpr43), FFAR3 (Gpr41), HCAR2 (Gpr109A), and Histone deacetylase (HDAC) that promotes microbiota-host crosstalk. Butyrate influences energy uptake, developmental and immune response in mammals. This microbial metabolite is produced by around 79 anaerobic genera present in the mammalian gut, yet little is known about the role of butyrate in the host-microbiota interaction in salmonid fish. To further our knowledge of this interaction, we analyzed the intestinal microbiota and genome of Atlantic salmon (Salmo salar), searching for butyrate-producing genera and host butyrate receptors. We identified Firmicutes, Proteobacteria, and Actinobacteria as the main butyrate-producing bacteria in the salmon gut microbiota. In the Atlantic salmon genome, we identified an expansion of genes orthologous to FFAR2 and HCAR2 receptors, and class I and IIa HDACs that are sensitive to butyrate. In addition, we determined the expression levels of orthologous of HCAR2 in the gut, spleen, and head-kidney, and FFAR2 in RTgutGC cells. The effect of butyrate on the Atlantic salmon immune response was evaluated by analyzing the pro and anti-inflammatory cytokines response in vitro in SHK-1 cells by RT-qPCR. Butyrate decreased the expression of the pro-inflammatory cytokine IL-1β and increased anti-inflammatory IL-10 and TGF-β cytokines. Butyrate also reduced the expression of interferon-alpha, Mx, and PKR, and decreased the viral load at a higher concentration (4 mM) in cells treated with this molecule before the infection with Infectious Pancreatic Necrosis Virus (IPNV) by mechanisms independent of FFAR2, FFAR3 and HCAR2 expression that probably inhibit HDAC. Moreover, butyrate modified phosphorylation of cytoplasmic proteins in RTgutGC cells. Our data allow us to infer that Atlantic salmon have the ability to sense butyrate produced by their gut microbiota via different specific targets, through which butyrate modulates the immune response of pro and anti-inflammatory cytokines and the antiviral response. © 2023 The AuthorsÍtem 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 Mobile genetic elements drive the multidrug resistance and spread of Salmonella serotypes along a poultry meat production line(Frontiers Media S.A., 2023-03) Krüger, Gabriel I.; Pardo-Esté, Coral; Zepeda, Phillippi; Olivares-Pacheco, Jorge; Galleguillos, Nicolas; Suarez, Marcia; Castro-Severyn, Juan; Alvarez-Thon, Luis; Tello, Mario; Valdes, Jorge H.; Saavedra, Claudia P.The presence of mobile genetic elements in Salmonella isolated from a chicken farm constitutes a potential risk for the appearance of emerging bacteria present in the food industry. These elements contribute to increased pathogenicity and antimicrobial resistance through genes that are related to the formation of biofilms and resistance genes contained in plasmids, integrons, and transposons. One hundred and thirty-three Salmonella isolates from different stages of the production line, such as feed manufacturing, hatchery, broiler farm, poultry farm, and slaughterhouse, were identified, serotyped and sequenced. The most predominant serotype was Salmonella Infantis. Phylogenetic analyses demonstrated that the diversity and spread of strains in the pipeline are serotype-independent, and that isolates belonging to the same serotype are very closely related genetically. On the other hand, Salmonella Infantis isolates carried the pESI IncFIB plasmid harboring a wide variety of resistance genes, all linked to mobile genetic elements, and among carriers of these plasmids, the antibiograms showed differences in resistance profiles and this linked to a variety in plasmid structure, similarly observed in the diversity of Salmonella Heidelberg isolates carrying the IncI1-Iα plasmid. Mobile genetic elements encoding resistance and virulence genes also contributed to the differences in gene content. Antibiotic resistance genotypes were matched closely by the resistance phenotypes, with high frequency of tetracycline, aminoglycosides, and cephalosporins resistance. In conclusion, the contamination in the poultry industry is described throughout the entire production line, with mobile genetic elements leading to multi-drug resistant bacteria, thus promoting survival when challenged with various antimicrobial compounds. Copyright © 2023 Krüger, Pardo-Esté, Zepeda, Olivares-Pacheco, Galleguillos, Suarez, Castro-Severyn, Alvarez-Thon, Tello, Valdes and Saavedra.Ítem Participation of the Salmonella OmpD porin in the infection of RAW264.7 macrophages and BALB/c mice(Public Library of Science, 2014) Ipinza, Francisco; Collao, Bernardo; Monsalva, Debbie; Bustamante, Victor H.; Luraschi, Roberto; Alegría-Arcos, Melissa; Almonacid, Daniel E.; Aguayo, Daniel; Calderón, Iván L.; Gil, Fernando; Santiviago, Carlos A.; Morales, Eduardo H.; Calva, Edmundo; Saavedra, Claudia P.Salmonella Typhimurium is the etiological agent of gastroenteritis in humans and enteric fever in mice. Inside these hosts, Salmonella must overcome hostile conditions to develop a successful infection, a process in which the levels of porins may be critical. Herein, the role of the Salmonella Typhimurium porin OmpD in the infection process was assessed for adherence, invasion and proliferation in RAW264.7 mouse macrophages and in BALB/c mice. In cultured macrophages, a ΔompD strain exhibited increased invasion and proliferation phenotypes as compared to its parental strain. In contrast, overexpression of ompD caused a reduction in bacterial proliferation but did not affect adherence or invasion. In the murine model, the ΔompD strain showed increased ability to survive and replicate in target organs of infection. The ompD transcript levels showed a down-regulation when Salmonella resided within cultured macrophages and when it colonized target organs in infected mice. Additionally, cultured macrophages infected with the ΔompD strain produced lower levels of reactive oxygen species, suggesting that down-regulation of ompD could favor replication of Salmonella inside macrophages and the subsequent systemic dissemination, by limiting the reactive oxygen species response of the host. © 2014 Ipinza et al.Ítem The ArcB kinase sensor participates in the phagocyte-mediated stress response in Salmonella Typhimurium(Frontiers Media SA, 2025) Pardo-Esté, Coral; Urbina, Francisca; Aviles, Nicolas; Pacheco, Nicolas; Briones, Alan; Cabezas, Carolina; Rojas, Vicente; Pavez, Valentina; Sulbaran-Bracho, Yoelvis; Hidalgo, Alejandro A.; Castro-Severyn, Juan; Saavedra, Claudia P.The ArcAB two-component system includes a histidine kinase sensor (ArcB) and a regulator (ArcA) that respond to changes in cell oxygen availability. The ArcA transcription factor activates genes related to metabolism, membrane permeability, and virulence, and its presence is required for pathogenicity in Salmonella Typhimurium, which can be phosphorylated independently of its cognate sensor, ArcB. In this study, we aimed to characterize the transcriptional response to hypochlorous acid (HOCl) mediated by the presence of the ArcB sensor. HOCl is a powerful microbicide widely used for sanitization in industrial settings. We used wild-type S. Typhimurium and the mutant lacking the arcB gene exposed to NaOCl to describe the global transcriptional response. We also infected murine neutrophils to evaluate the expression levels of relevant genes related to the resistance and infection process while facing ROS-related stress. Our results indicate that the absence of the arcB gene significantly affects the ability of S. Typhimurium to grow under HOCl stress. Overall, 6.6% of Salmonella genes varied their expression in the mutant strains, while 8.6% changed in response to NaOCl. The transcriptional response associated with the presence of ArcB is associated with metabolism and virulence, suggesting a critical role in pathogenicity and fitness, especially under ROS-related stress. Our results show that ArcB influences the expression of genes associated with fatty acid degradation, protein secretion, cysteine and H2S biosynthesis, and translation, both in vitro and under conditions found within neutrophils. We found that protein carbonylation is significantly higher in the mutant strain than in the wild type, suggesting a critical function for ArcB in the response and repair processes. This study contributes to the understanding of the pathogenicity and adaptation mechanisms that Salmonella employs to establish a successful infection in its host.Ítem The small RNA RyhB homologs from Salmonella typhimurium participate in the response to S-nitrosoglutathione-induced stress(Academic Press Inc., 2014-07) Calderón, Paulina F.; Morales, Eduardo H.; Acuña, Lillian G.; Fuentes, Danitza N.; Gil, Fernando; Porwollik, S.; McClelland, Michael; Saavedra, Claudia P.; Calderón, Iván L.Typically, the expression of sRNAs is activated in response to environmental stimuli in order to regulate gene expression through post-transcriptional mechanisms. In the present work we show that the Salmo nella typhimurium paralogous sRNAs RyhB-1 and RyhB-2 are induced in response to the nitrosating agent S-nitrosoglutathione (GSNO). Inactivation of these sRNAs decreased S. typhimurium resistance to GSNO and increased the levels of nitrosylated proteins. These results prompted us to evaluate a possible role of these sRNAs in nitrosative stress resistance. RNA profiling was used as a screen to identify novel RyhB-1 and RyhB-2 regulated targets. A subset of genes was filtered based on their potential role in the response to nitrosative stress and their expression was analyzed by quantitative RT-PCR in wild type, single and double mutant strains (DryhB1, DryhB2 and DryhB1 DryhB2) treated with GSNO. In response to GSNO RyhB-1 and RyhB-2 negatively regulate the expression of the genes cyoABC (cytochrome bo oxi dase), cydB (cytochrome bd oxidase), cybC (cytochrome b-562), and positively regulate the nirBCD operon (nitrite reductase system). Together, these results suggest that RyhB-1 and RyhB-2 finely tune the expres sion of genes coding for cytochrome oxidases and the nitrate reductase system, allowing the cell to cope with GSNO-induced stress. 2014 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).Ítem The Transcription Factor ArcA Modulates Salmonella’s Metabolism in Response to Neutrophil Hypochlorous Acid-Mediated Stress(Frontiers Media S.A., 2019-12) Pardo-Esté, Coral; Castro-Severyn, Juan; I. Krüger, Gabriel; Cabezas, Carolina Elizabeth; Briones, Alan Cristóbal; Aguirre, Camila; Morales, Naiyulin; Baquedano, Maria Soledad; Sulbaran, Yoelvis Noe; Hidalgo, Alejandro A.; Meneses, Claudio; Poblete-Castro, Ignacio; Castro-Nallar, Eduardo; Valvano, Miguel A.; Saavedra, Claudia P.Salmonella Typhimurium, a bacterial pathogen with high metabolic plasticity, can adapt to different environmental conditions; these traits enhance its virulence by enabling bacterial survival. Neutrophils play important roles in the innate immune response, including the production of microbicidal reactive oxygen species (ROS). In addition, the myeloperoxidase in neutrophils catalyzes the formation of hypochlorous acid (HOCl), a highly toxic molecule that reacts with essential biomolecules, causing oxidative damage including lipid peroxidation and protein carbonylation. The bacterial response regulator ArcA regulates adaptive responses to oxygen levels and influences the survival of Salmonella inside phagocytic cells. Here, we demonstrate by whole transcriptomic analyses that ArcA regulates genes related to various metabolic pathways, enabling bacterial survival during HOCl-stress in vitro. Also, inside neutrophils, ArcA controls the transcription of several metabolic pathways by downregulating the expression of genes related to fatty acid degradation, lysine degradation, and arginine, proline, pyruvate, and propanoate metabolism. ArcA also upregulates genes encoding components of the oxidative pathway. These results underscore the importance of ArcA in ATP generation inside the neutrophil phagosome and its participation in bacterial metabolic adaptations during HOCl stress. © Copyright © 2019 Pardo-Esté, Castro-Severyn, Krüger, Cabezas, Briones, Aguirre, Morales, Baquedano, Sulbaran, Hidalgo, Meneses, Poblete-Castro, Castro-Nallar, Valvano and Saavedra.