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9. Unraveling the genome of Bacillus velezensis MEP218, a strain producing fengycin homologs with broad antibacterial activity: comprehensive comparative genome analysis

Author

Contreras-Moreira, Bruno [0000-0002-5462-907X], Medeot, Daniela, Sannazzaro, Analía, Estrella, María Julia, Torres Tejerizo, Gonzalo, Contreras-Moreira, Bruno, Pistorio, Mariano, Jofré, Edgardo, Contreras-Moreira, Bruno [0000-0002-5462-907X], Medeot, Daniela, Sannazzaro, Analía, Estrella, María Julia, Torres Tejerizo, Gonzalo, Contreras-Moreira, Bruno, Pistorio, Mariano, and Jofré, Edgardo

Abstract

Bacillus sp. MEP218, a soil bacterium with high potential as a source of bioactive molecules, produces mostly C16–C17 fengycin and other cyclic lipopeptides (CLP) when growing under previously optimized culture conditions. This work addressed the elucidation of the genome sequence of MEP218 and its taxonomic classification. The genome comprises 3,944,892 bp, with a total of 3474 coding sequences and a G + C content of 46.59%. Our phylogenetic analysis to determine the taxonomic position demonstrated that the assignment of the MEP218 strain to Bacillus velezensis species provides insights into its evolutionary context and potential functional attributes. The in silico genome analysis revealed eleven gene clusters involved in the synthesis of secondary metabolites, including non-ribosomal CLP (fengycins and surfactin), polyketides, terpenes, and bacteriocins. Furthermore, genes encoding phytase, involved in the release of phytic phosphate for plant and animal nutrition, or other enzymes such as cellulase, xylanase, and alpha 1–4 glucanase were detected. In vitro antagonistic assays against Salmonella typhimurium, Acinetobacter baumanii, Escherichia coli, among others, demonstrated a broad spectrum of C16–C17 fengycin produced by MEP218. MEP218 genome sequence analysis expanded our understanding of the diversity and genetic relationships within the Bacillus genus and updated the Bacillus databases with its unique trait to produce antibacterial fengycins and its potential as a resource of biotechnologically useful enzymes.

Published
2023

10. Unraveling the genome of Bacillus velezensis MEP218, a strain producing fengycin homologs with broad antibacterial activity: comprehensive comparative genome analysis

Author

Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina), European Commission, Gobierno de Aragón, Contreras-Moreira, Bruno [0000-0002-5462-907X], Medeot, Daniela, Sannazzaro, Analia, Estrella, María Julia, Torres Tejerizo, Gonzalo, Contreras-Moreira, Bruno, Pistorio, Mariano, Jofré, Edgardo, Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina), European Commission, Gobierno de Aragón, Contreras-Moreira, Bruno [0000-0002-5462-907X], Medeot, Daniela, Sannazzaro, Analia, Estrella, María Julia, Torres Tejerizo, Gonzalo, Contreras-Moreira, Bruno, Pistorio, Mariano, and Jofré, Edgardo

Abstract

Bacillus sp. MEP218, a soil bacterium with high potential as a source of bioactive molecules, produces mostly C16–C17 fengycin and other cyclic lipopeptides (CLP) when growing under previously optimized culture conditions. This work addressed the elucidation of the genome sequence of MEP218 and its taxonomic classification. The genome comprises 3,944,892 bp, with a total of 3474 coding sequences and a G + C content of 46.59%. Our phylogenetic analysis to determine the taxonomic position demonstrated that the assignment of the MEP218 strain to Bacillus velezensis species provides insights into its evolutionary context and potential functional attributes. The in silico genome analysis revealed eleven gene clusters involved in the synthesis of secondary metabolites, including non-ribosomal CLP (fengycins and surfactin), polyketides, terpenes, and bacteriocins. Furthermore, genes encoding phytase, involved in the release of phytic phosphate for plant and animal nutrition, or other enzymes such as cellulase, xylanase, and alpha 1–4 glucanase were detected. In vitro antagonistic assays against Salmonella typhimurium, Acinetobacter baumanii, Escherichia coli, among others, demonstrated a broad spectrum of C16–C17 fengycin produced by MEP218. MEP218 genome sequence analysis expanded our understanding of the diversity and genetic relationships within the Bacillus genus and updated the Bacillus databases with its unique trait to produce antibacterial fengycins and its potential as a resource of biotechnologically useful enzymes.

Published
2023

11. Unraveling the genome of Bacillus velezensis MEP218, a strain producing fengycin homologs with broad antibacterial activity: comprehensive comparative genome analysis.

Author

Medeot, Daniela, Sannazzaro, Analía, Estrella, María Julia, Torres Tejerizo, Gonzalo, Contreras-Moreira, Bruno, Pistorio, Mariano, and Jofré, Edgardo

Subjects
BACILLUS (Bacteria), COMPARATIVE genomics, ANTIBACTERIAL agents, GENOMES, METABOLITES, SALMONELLA typhimurium, PHYTASES, TERPENES
Abstract

Bacillus sp. MEP218, a soil bacterium with high potential as a source of bioactive molecules, produces mostly C16–C17 fengycin and other cyclic lipopeptides (CLP) when growing under previously optimized culture conditions. This work addressed the elucidation of the genome sequence of MEP218 and its taxonomic classification. The genome comprises 3,944,892 bp, with a total of 3474 coding sequences and a G + C content of 46.59%. Our phylogenetic analysis to determine the taxonomic position demonstrated that the assignment of the MEP218 strain to Bacillus velezensis species provides insights into its evolutionary context and potential functional attributes. The in silico genome analysis revealed eleven gene clusters involved in the synthesis of secondary metabolites, including non-ribosomal CLP (fengycins and surfactin), polyketides, terpenes, and bacteriocins. Furthermore, genes encoding phytase, involved in the release of phytic phosphate for plant and animal nutrition, or other enzymes such as cellulase, xylanase, and alpha 1–4 glucanase were detected. In vitro antagonistic assays against Salmonella typhimurium, Acinetobacter baumanii, Escherichia coli, among others, demonstrated a broad spectrum of C16–C17 fengycin produced by MEP218. MEP218 genome sequence analysis expanded our understanding of the diversity and genetic relationships within the Bacillus genus and updated the Bacillus databases with its unique trait to produce antibacterial fengycins and its potential as a resource of biotechnologically useful enzymes. [ABSTRACT FROM AUTHOR]

Published
2023
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19. Cultural conditions required for the induction of an adaptive acid tolerance response (ATR) in Sinorhizobium meliloti and the question as to whetheror not theATR helps rhizobia improve their symbiosis with alfalfa at low pH

Author

Draghi, Walter Omar, del Papa, Maria Florencia, Pistorio, Mariano, Lozano, Mauricio Javier, Giusti, María de Los Ángeles, Torres Tejerizo, Gonzalo Arturo, Jofré, Edgardo, Boiardi, Jose Luis, and Lagares, Antonio

Subjects
Ciencias Biológicas, ATR, NODULATION, Biología Celular, Microbiología, RHIZOBIA, ACIDITY, COMPETITIVENESS, CIENCIAS NATURALES Y EXACTAS
Abstract

Sinorhizobium meliloti associates with Medicago and Melilotus species to develop nitrogen-fixing symbioses. The agricultural relevance of these associations, the worldwide distribution of acid soils, and the remarkable acid sensitivity of the microsymbiont have all stimulated research on the responses of the symbionts to acid environments. We show here that an adaptive acid-tolerance response (ATR) can be induced in S. meliloti, as shown previously for Sinorhizobium medicae, when the bacteria are grown in batch cultures at the slightly acid pH of 6.1. In marked contrast, no increased tolerance to hydrogen ions is obtained if rhizobia are grown in a chemostat under continuous cultivation at the same pH. The adaptive ATR appears as a complex process triggered by an increased hydrogen-ion concentration, but operative only if other--as yet unknown--concomitant factors that depend on the culture conditions are present (although not provided under continuous cultivation). Although the stability of the ATR and its influence on acid tolerance has been characterized in rhizobia, no data have been available on the effect of the adapted state on symbiosis. Coinoculation experiments showed that acid-adapted indicator rhizobia (ATR+) were present in >90% of the nodules when nodulation was performed at pH 5.6, representing a >30% increase in occupancy compared with a control test. We show that the ATR represents a clear advantage in competing for nodulation at low pH. It is not yet clear whether such an effect results from an improved performance in the acid environment during preinfection, an enhanced ability to initiate infections, or both conditions. The practical use of ATR+ rhizobia will depend on validation experiments with soil microcosms and on field testing, as well as on the possibility of preserving the physiology of ATR+ bacteria in inoculant formulations. Fil: Draghi, Walter Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentina Fil: del Papa, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentina Fil: Pistorio, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentina Fil: Lozano, Mauricio Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentina Fil: Giusti, María de Los Ángeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentina Fil: Torres Tejerizo, Gonzalo Arturo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentina Fil: Jofré, Edgardo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina Fil: Boiardi, Jose Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Lagares, Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Biotecnología y Biología Molecular. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Biotecnología y Biología Molecular; Argentina

Published
2019
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20. Los informes en Biología: el desafío de la comunicación escrita

Author

Principe, Analia, Ibañez, Fernando, Tonelli, Maria Laura, Anzuay, María Soledad, Bianucci, Eliana Carolina, Fernandez, Maricruz, Ludueña, Liliana Mercedes, Flores Cáceres, María Laura, Furlan, Ana Laura, Liaudat, Juan Pablo, Figueredo, María Soledad, Rodriguez Melo, Johan Stiben, Peralta, Juan Manuel, Muñoz, Vanina Laura, Magallanes Noguera, Cynthia Alejandra, Jofré, Edgardo, Vogliotti, Ana, Ledesma, María Luisa, Roldán, Carolina Isabel, and Clerici, Jimena Vanina

Subjects
purl.org/becyt/ford/5 [https], purl.org/becyt/ford/5.3 [https], INNOVACIONES PEDAGOGICAS, INNOVACIONES CURRICULARES
Abstract

La innovación constituye un aspecto muy valorado en la vida humana. La innovación pedagógica pareciera ser inherente a toda educación: enseñar y aprender suponen necesariamente la novedad. Si se repiten cosas conocidas por el estudiante, no hay enseñanza y, si este no se enfrenta con algo nuevo que lomovilice cognitivamente, tampoco hay aprendizaje, al menos significativo, profundo y de relevancia, de esos que son indispensables construir en una buena formación. Por ese motivo, diseñar, implementar y evaluar innovaciones pedagógicas son tareas muy complejas que requieren de conocimientos, tecnologíasy condiciones institucionales que promuevan el trabajo colaborativo e interdisciplinario desde paradigmas críticos fundamentados en políticas académicas que asuman a la relación teórico-práctica, a la inclusión ya la calidad educativa como sus pilares básicos.Este es el marco de los trabajos que se incluyen en esta publicación. Se trata de experiencias pedagógicas diseñadas e implementadas en las cinco facultades de la Universidad Nacional de Río Cuarto (UNRC) que se convirtieron en objeto de reflexión compartida de los equipos docentes que las impulsaron y quemuestran interés por hacerlas públicas; de esta manera, trascienden la microfísica del espacio del aula en donde cobraron vida. Es necesario darlas a conocer, por sus alcances y limitaciones, por las reflexiones que suscitan, por su potencial innovador y por la generosidad de sus autores para exponerlas a la crítica y al debate, con la expectativa de que los aportes recibidos vuelvan para enriquecer las experiencias y saberes en un sentido superador.En consonancia con su condición pública, en la UNRC la publicación de innovaciones constituye una práctica frecuente. Hay una disposición institucional para dar a conocer de manera abierta y generalizadalas diversas producciones tanto en el plano académico de la formación como en el ámbito de la investigación y la vinculación con los diversos contextos socioculturales y comunitarios. Se manifiesta permanentemente el interés por compartir, por hacer conocer, por visibilizar al trabajo, sus procesos y resultados; hacerlos públicos no solo para ser conocidos, sino también para que aporten al pensamiento y a la mejora y recepten las contribuciones del contexto.En este sentido, se asume el lema del escudo institucional que, desde su fundación, signa con fuerza a la cultura de la universidad. Apostar a los sujetos, a la comunidad, al trabajo y a la ciencia para construirconocimientos relevantes en una transformación encaminada hacia una sociedad más igualitaria y humana constituye el significado del símbolo que identifica a la institución. Por ello, creer, crear y crecer se imbrican con la innovación. Fil: Principe, Analia. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Ibañez, Fernando. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina Fil: Tonelli, Maria Laura. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Anzuay, María Soledad. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Bianucci, Eliana Carolina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Fernandez, Maricruz. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Ludueña, Liliana Mercedes. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Flores Cáceres, María Laura. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Furlan, Ana Laura. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Liaudat, Juan Pablo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Figueredo, María Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina Fil: Rodriguez Melo, Johan Stiben. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Peralta, Juan Manuel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Muñoz, Vanina Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina Fil: Magallanes Noguera, Cynthia Alejandra. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Investigaciones en Tecnología Química. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Investigaciones en Tecnología Química; Argentina Fil: Jofré, Edgardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquimicas y Naturales. Departamento de Ciencias Naturales. Cátedra de Biologia General; Argentina

Published
2019

23. The Sinorhizobium meliloti RNA chaperone Hfq influences central carbon metabolism and the symbiotic interaction with alfalfa

Author

Jiménez-Zurdo José I, Toro Nicolás, Rivilla Rafael, Lloret Javier, Jofré Edgardo, Peregrina Alexandra, Oruezabal Roke I, and Torres-Quesada Omar

Subjects
Microbiology, QR1-502
Abstract

Abstract Background The bacterial Hfq protein is able to interact with diverse RNA molecules, including regulatory small non-coding RNAs (sRNAs), and thus it is recognized as a global post-transcriptional regulator of gene expression. Loss of Hfq has an extensive impact in bacterial physiology which in several animal pathogens influences virulence. Sinorhizobium meliloti is a model soil bacterium known for its ability to establish a beneficial nitrogen-fixing intracellular symbiosis with alfalfa. Despite the predicted general involvement of Hfq in the establishment of successful bacteria-eukaryote interactions, its function in S. meliloti has remained unexplored. Results Two independent S. meliloti mutants, 2011-3.4 and 1021Δhfq, were obtained by disruption and deletion of the hfq gene in the wild-type strains 2011 and 1021, respectively, both exhibiting similar growth defects as free-living bacteria. Transcriptomic profiling of 1021Δhfq revealed a general down-regulation of genes of sugar transporters and some enzymes of the central carbon metabolism, whereas transcripts specifying the uptake and metabolism of nitrogen sources (mainly amino acids) were more abundant than in the wild-type strain. Proteomic analysis of the 2011-3.4 mutant independently confirmed these observations. Symbiotic tests showed that lack of Hfq led to a delayed nodulation, severely compromised bacterial competitiveness on alfalfa roots and impaired normal plant growth. Furthermore, a large proportion of nodules (55%-64%) elicited by the 1021Δhfq mutant were non-fixing, with scarce content in bacteroids and signs of premature senescence of endosymbiotic bacteria. RT-PCR experiments on RNA from bacteria grown under aerobic and microoxic conditions revealed that Hfq contributes to regulation of nifA and fixK1/K2, the genes controlling nitrogen fixation, although the Hfq-mediated regulation of fixK is only aerobiosis dependent. Finally, we found that some of the recently identified S. meliloti sRNAs co-inmunoprecipitate with a FLAG-epitope tagged Hfq protein. Conclusions Our results support that the S. meliloti RNA chaperone Hfq contributes to the control of central metabolic pathways in free-living bacteria and influences rhizospheric competence, survival of the microsymbiont within the nodule cells and nitrogen fixation during the symbiotic interaction with its legume host alfalfa. The identified S. meliloti Hfq-binding sRNAs are predicted to participate in the Hfq regulatory network.

Published
2010
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26. A matter of hierarchy: Activation of orfamide production by the posttranscriptional Gac-Rsm cascade of Pseudomonas protegens CHA0 through expression upregulation of the two dedicated transcriptional regulators

Author

Sobrero, Patricio Martín, Muzlera, Andrés, Frescura, Julieta Magali, Jofré, Edgardo, and Valverde, Claudio Fabián

Subjects
Ciencias Biológicas, PSEUDOMONAS PROTEGENS, GAC-RSM, POSTTRANSCRIPTIONAL CONTROL, TRANSCRIPTIONAL REGULATOR, Otras Ciencias Biológicas, ORFAMIDE, CIENCIAS NATURALES Y EXACTAS
Abstract

In this work, we surveyed the genome of P. protegens CHA0 in order to identify novel mRNAs possibly under the control of the Gac-Rsm cascade that might, for their part, serve to elucidate as-yet-unknown functions involved in the biocontrol of plant pathogens and/or in cellular processes required for fitness in natural environments. In view of the experimental evidence from former studies on the Gac-Rsm cascade, we developed a computational screen supported by a combination of sequence, structural, and evolutionary constraints that led to a dataset of 43 potential novel mRNA targets. We then confirmed several mRNA targets experimentally and next focused on two of the respective genes that are physically linked to the orfamide biosynthetic gene cluster and whose predicted open-reading frames resembled cognate LuxR-type transcriptional regulators of cyclic lipopeptide clusters in related pseudomonads. In this report, we demonstrate that in strain CHA0, orfamide production is stringently dependent on a functional Gac-Rsm cascade and that both mRNAs encoding transcriptional regulatory proteins are under direct translational control of the RsmA/E proteins. Our results have thus revealed a hierarchical control over the expression of orfamide biosynthetic genes with the final transcriptional control subordinated to the global Gac-Rsm posttranscriptional regulatory system. Fil: Sobrero, Patricio Martín. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; Argentina Fil: Muzlera, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; Argentina Fil: Frescura, Julieta Magali. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; Argentina Fil: Jofré, Edgardo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Ciencias Naturales; Argentina Fil: Valverde, Claudio Fabián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; Argentina

Published
2017
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28. Fengycins From Bacillus amyloliquefaciens MEP218 Exhibit Antibacterial Activity by Producing Alterations on the Cell Surface of the Pathogens Xanthomonas axonopodis pv. vesicatoria and Pseudomonas aeruginosa PA01.

Author

Medeot, Daniela B., Fernandez, Maricruz, Morales, Gustavo M., and Jofré, Edgardo

Subjects
XANTHOMONAS, BACILLUS amyloliquefaciens, PHYTOPATHOGENIC microorganisms, CELL membranes, PSEUDOMONAS aeruginosa, ATOMIC force microscopy, PSEUDOMONAS aeruginosa infections, PATHOGENIC microorganisms
Abstract

Bacillus amyloliquefaciens MEP218 is an autochthonous bacterial isolate with antibacterial and antifungal activities against a wide range of phytopathogenic microorganisms. Cyclic lipopeptides (CLP), particularly fengycins, produced by this bacterium; are the main antimicrobial compounds responsible for the growth inhibition of phytopathogens. In this work, the CLP fraction containing fengycins with antibacterial activity was characterized by LC-ESI-MS/MS. In addition, the antibacterial activity of these fengycins was evaluated on the pathogens Xanthomonas axonopodis pv. vesicatoria (Xav), a plant pathogen causing the bacterial spot disease, and Pseudomonas aeruginosa PA01, an opportunistic human pathogen. In vitro inhibition assays showed bactericidal effects on Xav and PA01. Atomic force microscopy images revealed dramatic alterations in the bacterial surface topography in response to fengycins exposure. Cell damage was evidenced by a decrease in bacterial cell heights and the loss of intracellular content measured by potassium efflux assays. Furthermore, the viability of MRC-5 human normal lung fibroblasts was not affected by the treatment with fengycins. This study shows in vivo evidence on the less-known properties of fengycins as antibacterial molecules and leaves open the possibility of using this CLP as a novel antibiotic. [ABSTRACT FROM AUTHOR]

Published
2020
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29. Sinorhizobium meliloti low molecular weight phosphotyrosine phosphatase SMc02309 modifies activity of the UDP-glucose pyrophosphorylase ExoN involved in succinoglycan biosynthesis

Author

Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina), Universidad Nacional de Río Cuarto (Argentina), German Research Foundation, State of Hesse, Medeot, Daniela B., Rivero, María Romina, Cendoya, Eugenia, Contreras-Moreira, Bruno, Rossi, Fernando A., Fischer, Sonia E., Becker, Anke, Jofré, Edgardo, Consejo Nacional de Investigaciones Científicas y Técnicas (Argentina), Universidad Nacional de Río Cuarto (Argentina), German Research Foundation, State of Hesse, Medeot, Daniela B., Rivero, María Romina, Cendoya, Eugenia, Contreras-Moreira, Bruno, Rossi, Fernando A., Fischer, Sonia E., Becker, Anke, and Jofré, Edgardo

Abstract

n Gram-negative bacteria, tyrosine phosphorylation has been shown to play a role in the control of exopolysaccharide (EPS) production. This study demonstrated that the chromosomal ORF SMc02309 from Sinorhizobium meliloti 2011 encodes a protein with significant sequence similarity to low molecular mass protein-tyrosine phosphatases (LMW-PTPs), such as the Escherichia coli Wzb. Unlike other well-characterized EPS biosynthesis gene clusters, which contain neighbouring LMW-PTPs and kinase, the S. meliloti succinoglycan (EPS I) gene cluster located on megaplasmid pSymB does not encode a phosphatase. Biochemical assays revealed that the SMc02309 protein hydrolyses p-nitrophenyl phosphate (p-NPP) with kinetic parameters similar to other bacterial LMW-PTPs. Furthermore, we show evidence that SMc02309 is not the LMW-PTP of the bacterial tyrosine-kinase (BY-kinase) ExoP. Nevertheless, ExoN, a UDP-glucose pyrophosphorylase involved in the first stages of EPS I biosynthesis, is phosphorylated at tyrosine residues and constitutes an endogenous substrate of the SMc02309 protein. Additionally, we show that the UDP-glucose pyrophosphorylase activity is modulated by SMc02309-mediated tyrosine dephosphorylation. Moreover, a mutation in the SMc02309 gene decreases EPS I production and delays nodulation on Medicago sativa roots.

Published
2016

31. The Sinorhizobium meliloti RNA chaperone Hfq influences central carbon metabolism and the symbiotic interaction with alfalfa

Author

Torres Quesada, Omar, Oruezábal, Roke I., Peregrina, Alexandra, Jofré, Edgardo, Lloret, Javier, Rivilla, Rafael, Toro, Nicolás, Jiménez-Zurdo, José I., Torres Quesada, Omar, Oruezábal, Roke I., Peregrina, Alexandra, Jofré, Edgardo, Lloret, Javier, Rivilla, Rafael, Toro, Nicolás, and Jiménez-Zurdo, José I.

Abstract

[Background] The bacterial Hfq protein is able to interact with diverse RNA molecules, including regulatory small non-coding RNAs (sRNAs), and thus it is recognized as a global post-transcriptional regulator of gene expression. Loss of Hfq has an extensive impact in bacterial physiology which in several animal pathogens influences virulence. Sinorhizobium meliloti is a model soil bacterium known for its ability to establish a beneficial nitrogen-fixing intracellular symbiosis with alfalfa. Despite the predicted general involvement of Hfq in the establishment of successful bacteria-eukaryote interactions, its function in S. meliloti has remained unexplored., [Results] Two independent S. meliloti mutants, 2011-3.4 and 1021Deltahfq, were obtained by disruption and deletion of the hfq gene in the wild-type strains 2011 and 1021, respectively, both exhibiting similar growth defects as free-living bacteria. Transcriptomic profiling of 1021Deltahfq revealed a general down-regulation of genes of sugar transporters and some enzymes of the central carbon metabolism, whereas transcripts specifying the uptake and metabolism of nitrogen sources (mainly amino acids) were more abundant than in the wild-type strain. Proteomic analysis of the 2011-3.4 mutant independently confirmed these observations. Symbiotic tests showed that lack of Hfq led to a delayed nodulation, severely compromised bacterial competitiveness on alfalfa roots and impaired normal plant growth. Furthermore, a large proportion of nodules (55%-64%) elicited by the 1021Deltahfq mutant were non-fixing, with scarce content in bacteroids and signs of premature senescence of endosymbiotic bacteria. RT-PCR experiments on RNA from bacteria grown under aerobic and microoxic conditions revealed that Hfq contributes to regulation of nifA and fixK1/K2, the genes controlling nitrogen fixation, although the Hfq-mediated regulation of fixK is only aerobiosis dependent. Finally, we found that some of the recently identified S. meliloti sRNAs co-inmunoprecipitate with a FLAG-epitope tagged Hfq protein., [Conclusions] Our results support that the S. meliloti RNA chaperone Hfq underlies the control of central metabolic pathways in free-living bacteria and influences rhizospheric competence, survival of the microsymbiont within the nodule cells and nitrogen fixation during the symbiotic interaction with its legume host alfalfa. The identified S. meliloti Hfq-binding sRNAs are predicted to participate in the Hfq regulatory network.

Published
2010

40. Cultural conditions required for the induction of an adaptive acid-tolerance response (ATR) in Sinorhizobium meliloti and the question as to whether or not the ATR helps rhizobia improve their symbiosis with alfalfa at low pH.

Author

Draghi, Walter O., Del Papa, María Florencia, Pistorio, Mariano, Lozano, Mauricio, de los Ángeles Giusti, María, Torres Tejerizo, Gonzalo A., Jofré, Edgardo, Boiardi, José Luis, and Lagares, Antonio

Subjects
RHIZOBIACEAE, SYMBIOSIS, PROKARYOTES, FUNGUS-bacterium relationships, FORAGE plants, ACIDITY function, ACID soils, CONTINUOUS culture (Microbiology), RHIZOBIUM
Abstract

Sinorhizobium meliloti associates with Medicago and Melilotus species to develop nitrogen-fixing symbioses. The agricultural relevance of these associations, the worldwide distribution of acid soils, and the remarkable acid sensitivity of the microsymbiont have all stimulated research on the responses of the symbionts to acid environments. We show here that an adaptive acid-tolerance response (ATR) can be induced in S. meliloti, as shown previously for Sinorhizobium medicae, when the bacteria are grown in batch cultures at the slightly acid pH of 6.1. In marked contrast, no increased tolerance to hydrogen ions is obtained if rhizobia are grown in a chemostat under continuous cultivation at the same pH. The adaptive ATR appears as a complex process triggered by an increased hydrogen-ion concentration, but operative only if other – as yet unknown – concomitant factors that depend on the culture conditions are present (although not provided under continuous cultivation). Although the stability of the ATR and its influence on acid tolerance has been characterized in rhizobia, no data have been available on the effect of the adapted state on symbiosis. Coinoculation experiments showed that acid-adapted indicator rhizobia (ATR+) were present in >90% of the nodules when nodulation was performed at pH 5.6, representing a >30% increase in occupancy compared with a control test. We show that the ATR represents a clear advantage in competing for nodulation at low pH. It is not yet clear whether such an effect results from an improved performance in the acid environment during preinfection, an enhanced ability to initiate infections, or both conditions. The practical use of ATR+ rhizobia will depend on validation experiments with soil microcosms and on field testing, as well as on the possibility of preserving the physiology of ATR+ bacteria in inoculant formulations. [ABSTRACT FROM AUTHOR]

Published
2010
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41. Role of a serine-typed-alanyl-d-alanine carboxypeptidase on the survival of Ochrobactrum sp. 11a under ionic and hyperosmotic stress.

Author

Príncipe, Analía, Jofré, Edgardo, Alvarez, Florencia, and Mori, Gladys

Subjects
*CARBOXYPEPTIDASES, *RHIZOBIUM japonicum, *SALINITY, *POLYETHYLENE glycol, *MICROBIAL exopolysaccharides, *TRANSPOSONS, *MUTAGENESIS, *THERAPEUTICS
Abstract

The plant growth-promoting rhizobacterium, Ochrobactrum sp. 11a displays a high intrinsic salinity tolerance and has been used in this work to study the molecular basis of bacterial responses to high concentrations of NaCl. A collection of Ochrobactrum sp. 11a mutants was generated by Tn 5-B21 mutagenesis and screened for sensitivity to salinity. One clone, designated PBP and unable to grow on glutamate mannitol salt agar medium supplemented with 300 mM NaCl was selected and further characterized. The PBP mutant carries a single transposon insertion in a gene showing a high degree of identity to the serine-typed-alanyl-d-alanine carboxypeptidase gene of Ochrobactrum anthropi. Interestingly, the expression of this gene was shown to be upregulated by salt in the PBP mutant. Moreover, evidence is presented for the requirement of the gene product for adaptation to high-salt conditions as well as to overcome the toxicity of LiCl, KCl, sucrose, polyethylene glycol (PEG), AlCl3, CuSO4, and ZnSO4. In addition to the altered tolerance to both ionic and osmotic stresses, the PBP mutant exhibited changes in colony and cell morphology, exopolysaccharide production, and an increased sensitivity to detergents. [ABSTRACT FROM AUTHOR]

Published
2009
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42. Mutation in ad-alanine–d-alanine ligase of Azospirillum brasilense Cd results in an overproduction of exopolysaccharides and a decreased tolerance to saline stress.

Author

Jofré, Edgardo, Fischer, Sonia, Príncipe, Analía, Castro, Marina, Ferrari, Walter, Lagares, Antonio, and Mori, Gladys

Subjects
*GENETIC mutation, *LIGASES, *AZOSPIRILLUM, *MICROBIAL exopolysaccharides, *BACTERIA, *RHIZOBACTERIA, *PLANT roots, *GENETICS, *BIOCHEMISTRY, *BIOSYNTHESIS
Abstract

Bacteria of the genus Azospirillum are free-living nitrogen-fixing, rhizobacteria that are found in close association with plant roots, where they exert beneficial effects on plant growth and yield in many crops of agronomic importance. Unlike other bacteria, little is known about the genetics and biochemistry of exopolysaccharides in Azospirillum brasilense. In an attempt to characterize genes associated with exopolysaccharides production, we generated an A. brasilense Cd Tn 5 mutant that showed exopolysaccharides overproduction, decreased tolerance to saline conditions, altered cell morphology, and increased sensitivity to detergents. Genetic characterization showed that the Tn 5 was inserted within a ddlB gene encoding for ad-alanine–d-alanine ligase, and located upstream of the ftsQAZ gene cluster responsible for cell division in different bacteria. Heterologous complementation of the ddlB Tn 5 mutant restored the exopolysaccharides production to wild-type levels and the ability to grow in the presence of detergents, but not the morphology and growth characteristics of the wild-type bacteria, suggesting a polar effect of Tn 5 on the fts genes. This result and the construction of a nonpolar ddlB mutant provide solid evidence of the presence of transcriptional coupling between a gene associated with peptidoglycan biosynthesis and the fts genes required to control cell division. [ABSTRACT FROM AUTHOR]

Published
2009
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43. Disruption of dTDP-rhamnose biosynthesis modifies lipopolysaccharide core, exopolysaccharide production, and root colonization in Azospirillum brasilense

Author

Jofré, Edgardo, Lagares, Antonio, and Mori, Gladys

Subjects
*ENDOTOXINS, *MICROBIAL exopolysaccharides, *GAS chromatography, *AZOSPIRILLUM
Abstract

The interaction between Azospirillum brasilense and plants is not fully understood, although several bacterial surface components like exopolysaccharides (EPS), flagella, and capsular polysaccharides are required for attachment and colonization. While in other plant–bacteria associations (Rhizobium–legume, Pseudomonas–potato), lipopolysaccharides (LPS) play a key role in the establishment of an effective association, their role in the root colonization by Azospirillum had not been determined. In this study, we isolated a Tn5 mutant of A. brasilense Cd (EJ1) with an apparently modified LPS core structure, non-mucoid colony morphology, increased EPS production, and affected in maize root colonization. A 3790-bp region revealed the presence of three complete open reading frames designated rmlC, rmlB and rmlD. The beginning of a fourth open reading frame was found and designated rmlA. These genes are organized in a cluster which shows homology to the cluster involved in the synthesis of dTDP-rhamnose in other bacteria. Additionally, the analysis of the monosaccharide composition of LPSs showed a diminution of rhamnose compared to the wild-type strain. [Copyright &y& Elsevier]

Published
2004
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44. Fengycins From Bacillus amyloliquefaciens MEP 2 18 Exhibit Antibacterial Activity by Producing Alterations on the Cell Surface of the Pathogens Xanthomonas axonopodis pv. vesicatoria and Pseudomonas aeruginosa PA01.

Author

Medeot DB, Fernandez M, Morales GM, and Jofré E

Abstract

Bacillus amyloliquefaciens MEP 2 18 is an autochthonous bacterial isolate with antibacterial and antifungal activities against a wide range of phytopathogenic microorganisms. Cyclic lipopeptides (CLP), particularly fengycins, produced by this bacterium; are the main antimicrobial compounds responsible for the growth inhibition of phytopathogens. In this work, the CLP fraction containing fengycins with antibacterial activity was characterized by LC-ESI-MS/MS. In addition, the antibacterial activity of these fengycins was evaluated on the pathogens Xanthomonas axonopodis pv. vesicatoria (Xav), a plant pathogen causing the bacterial spot disease, and Pseudomonas aeruginosa PA01, an opportunistic human pathogen. In vitro inhibition assays showed bactericidal effects on Xav and PA01. Atomic force microscopy images revealed dramatic alterations in the bacterial surface topography in response to fengycins exposure. Cell damage was evidenced by a decrease in bacterial cell heights and the loss of intracellular content measured by potassium efflux assays. Furthermore, the viability of MRC-5 human normal lung fibroblasts was not affected by the treatment with fengycins. This study shows in vivo evidence on the less-known properties of fengycins as antibacterial molecules and leaves open the possibility of using this CLP as a novel antibiotic., (Copyright © 2020 Medeot, Fernandez, Morales and Jofré.)

Published
2020
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