Examinando por Autor "Suárez, Cristian Alejandro"
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Ítem Acceso Abierto Bioinformática aplicada a la caracterización genómica y clasificación de bacteriófagos de Staphylococcus aureus(2019) Moyano, María Soledad Rita; Suárez, Cristian AlejandroEl incremento de la resistencia bacteriana (como en Staphylococcus aureus) por la presión selectiva que representa la utilización de antibióticos a gran escala, sobre todo en nuestros hospitales (también en sectores agrícolas y alimenticios), ha permitido la diseminación de cepas con mecanismos de resistencia que, en muchas ocasiones, nos dejan prácticamente sin alternativas para el tratamiento de las infecciones bacterianas; culminando en consecuencias mortales. Por eso, es necesario el desarrollo de nuevas terapias para el control de infecciones producidas por estos microorganismos. Los bacteriófagos son virus que infectan bacterias de una manera altamente específica y tienen la capacidad de destruirlas. Por otro lado, los bacteriófagos poseen un rol crucial en patogénesis y virulencia debido a la capacidad que tienen algunos de ellos de favorecer la transferencia de genes. En la actualidad, gracias al aumento constante del número de bacteriófagos aislados y secuenciados, sumado al desarrollo de diversas herramientas para analizar dichos fagos, ha resurgido el interés para utilizar a los fagos con finalidades terapéuticas y/o diagnósticas. Durante la presente tesina, se ha llevado a cabo la caracterización y análisis bioinformático de un bacteriófago específico de Staphylococcus aureus (fago I74, previamente aislado en el mismo laboratorio de trabajo), perteneciente a la familia Siphoviridae. Los análisis realizados comprenden, la anotación genómica y genómica comparativa utilizando fagos presentes en las bases de datos. Esta gran cantidad de información genética de numerosos bacteriófagos de S. aureus, permite un enfoque sistemático para estudiar la diversidad y evolución de los mismos y aportan datos sobre la transferencia de genes de virulencia entre las cepas bacterianas.Ítem Acceso Abierto Expression of the agmatine deiminase pathway in Enterococcus faecalis is activated by the AguR regulator and repressed by CcpA and PTS(Man) systems(Public Library of Science, 2013-10-14) Suárez, Cristian Alejandro; Espariz, Martín; Blancato, Víctor Sebastián; Magni, ChristianAlthough the agmatine deiminase system (AgDI) has been investigated in Enterococcus faecalis, little information is available with respect to its gene regulation. In this study we demonstrate that the presence of exogenous agmatine induces the expression of agu genes in this bacterium. In contrast to the homologous and extensively characterized AgDI system of S. mutants, the aguBDAC operon in E. faecalis is not induced in response to low pH. In spite of this, agmatine catabolism in this bacterium contributes by neutralizing the external medium while enhancing bacterial growth. Our results indicate that carbon catabolic repression (CCR) operates on the AgDI system via a mechanism that involves interaction of CcpA and PSer-HPr with a cre site found in an unusual position considering the aguB promoter (55 nt upstream the +1 position). In addition, we found that components of the mannose phosphotransferase (PTSMan) system also contributed to CCR in E. faecalis since a complete relief of the PTS-sugars repressive effect was observed only in a PTSMan and CcpA double defective strain. Our gene context analysis revealed that aguR is present in oral and gastrointestinal microorganisms. Thus, regulation of the aguBDAC operon in E. faecalis seems to have evolved to obtain energy and resist low pH conditions in order to persist and colonize gastrointestinal niches.Ítem Acceso Abierto Genomic comparative analysis of the environmental Enterococcus mundtii against enterococcal representative species(BMC, 2014-06-18) Repizo, Guillermo Daniel; Espariz, Martín; Blancato, Víctor Sebastián; Suárez, Cristian Alejandro; Esteban, Luis; Magni, ChristianBackground Enterococcus mundtii is a yellow-pigmented microorganism rarely found in human infections. The draft genome sequence of E. mundtii was recently announced. Its genome encodes at least 2,589 genes and 57 RNAs, and 4 putative genomic islands have been detected. The objective of this study was to compare the genetic content of E. mundtii with respect to other enterococcal species and, more specifically, to identify genes coding for putative virulence traits present in enterococcal opportunistic pathogens. Results An in-depth mining of the annotated genome was performed in order to uncover the unique properties of this microorganism, which allowed us to detect a gene encoding the antimicrobial peptide mundticin among other relevant features. Moreover, in this study a comparative genomic analysis against commensal and pathogenic enterococcal species, for which genomic sequences have been released, was conducted for the first time. Furthermore, our study reveals significant similarities in gene content between this environmental isolate and the selected enterococci strains (sharing an “enterococcal gene core” of 805 CDS), which contributes to understand the persistence of this genus in different niches and also improves our knowledge about the genetics of this diverse group of microorganisms that includes environmental, commensal and opportunistic pathogens. Conclusion Although E. mundtii CRL1656 is phylogenetically closer to E. faecium, frequently responsible of nosocomial infections, this strain does not encode the most relevant relevant virulence factors found in the enterococcal clinical isolates and bioinformatic predictions indicate that it possesses the lowest number of putative pathogenic genes among the most representative enterococcal species. Accordingly, infection assays using the Galleria mellonella model confirmed its low virulence.