Rifampicin quinone pretreatment improves neuronal survival by modulating microglia inflammation induced by α-synuclein

The World Health Organization has predicted that neurodegenerative diseasesaffecting the motor function will become the second most prevalent cause ofdeath in the next 20 years. New therapies can result from three main sources:synthetic compounds, natural products, and existing drugs. Parkinson?s disease (PD) is a common neurodegenerative disease affecting 1?3% of the adult population over 50 years of age worldwide. It is initially characterized by the death of dopaminergic neurons in the substantia nigra pars compact and later by the widespread loss of nondopaminergic neurons, including those in the cortex (Goedert et al., 2013). Inflammation is the main underlying cause in most, if not all, neurodegenerative diseases, playing a protective role in their initial acute phases, but a pernicious one in their later chronic phases. Increasing evidence has disclosed that microglia-mediated neuroinflammation is crucial for PD progression (Hirsch and Hunot, 2009). Another neuropathological hallmark of PD is the presence of Lewy bodies, which are primarily composed of α-synuclein (α-Syn) aggregates (Goedert et al., 2013). In recent years, important studies on the role of α-Syn in PD have been conducted. The α-Syn aggregation in the central nervous system is a pathological process of fundamental importance in the development and progression of PD. Aggregates of α-Syn, in oligomeric and fibril forms, are thought to be capable of causing neurodegeneration either by directly damaging neurons or by activating microglia to produce neuroinflammatory mediators, which are neurotoxic (Hirsch and Hunot, 2009). Due to the consequent neuronal damage, an aggregation and release process of endogenous α-Syn occurs, triggering microglial activation and leading to neuroinflammation (Sanchez-Guajardo et al., 2015). In this way, α-Syn aggregates generate a vicious circle of neuroinflammation and neuronal death in PD. The interaction between these two players, α-Syn aggregates and microglial cells, is thus believed to be strongly implicated in the inflammatory process that accompanies PD progression. However, the molecular mechanisms that underlie α-Syn-induced microglia activation are not well understood.Fil: Acuña, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Patología Experimental. Universidad Nacional de Salta. Facultad de Ciencias de la Salud. Instituto de Patología Experimental; ArgentinaFil: Corbalan, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta; Argentina. Universidad Nacional de Salta; ArgentinaFil: Raisman Vozari, Rita. Centre de Recherche de I'Institut du Cerveau et de la Moelle Epinière; Francia. Sorbonne University; Francia. Inserm; Franci

Macrophage environment turns otherwise MccJ25-resistant Salmonella into sensitive

In this work we demonstrate that S. Typhimurium becomes notably susceptible to MccJ25 when replicating within macrophages. In order to determine the possible cause of this phenomenon, we studied the sensitivity of S. Typhimurium to MccJ25 at conditions resembling those of the internal macrophage environment, such as low pH, low magnesium and iron deprivation. We observed that the strain was only sensitive to the antibiotic at low pH, leading us to attribute the bacterial sensitization to this condition. A MccJ25-resistant E. coli strain in which fhuA is deleted was also inhibited by the antibiotic at low pH. Then, we could assume that the MccJ25 sensitivity change observed in both E. coli fhuA and S. Typhimurium is mediated by a MccJ25 uptake independent of the FhuA receptor. Moreover, low pH incubation also sensitized S. Typhimurium to the hydrophobic antibiotic novobiocin, which does not affect enteric bacteria viability because it is unable to penetrate the bacterial outer membrane. This observation supports our hypothesis about low pH producing a modification in the bacterial membrane permeability that allows an unspecific MccJ25 uptake. On the other hand, MccJ25 inhibited S. Typhimurium when cells were preincubated in acidic pH medium and then treated at neutral pH with the antibiotic.Fil: Pomares, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tucuman. Instituto Superior de Investigaciones Biológicas; Argentina;Fil: Corbalan, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tucuman. Instituto Superior de Investigaciones Biológicas; Argentina;Fil: Adler, Conrado. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tucuman. Instituto Superior de Investigaciones Biológicas; Argentina;Fil: de Cristobal, Ricardo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tucuman. Instituto Superior de Investigaciones Biológicas; Argentina;Fil: Farias, Ricardo Norberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tucuman. Instituto Superior de Investigaciones Biológicas; Argentina;Fil: Delgado, Monica Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tucuman. Instituto Superior de Investigaciones Biológicas; Argentina;Fil: Vincent, Paula Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Tucuman. Instituto Superior de Investigaciones Biológicas; Argentina

Rifampicin and Its Derivative Rifampicin Quinone Reduce Microglial Inflammatory Responses and Neurodegeneration Induced In Vitro by α-Synuclein Fibrillary Aggregates

Abstract: Aggregated forms of the synaptic protein α‐synuclein (αS) have been proposed to operateas a molecular trigger for microglial inflammatory processes and neurodegeneration in Parkinson´sdisease. Here, we used brain microglial cell cultures activated by fibrillary forms of recombinanthuman αS to assess the anti‐inflammatory and neuroprotective activities of the antibiotic rifampicin(Rif) and its autoxidation product rifampicin quinone (RifQ). Pretreatments with Rif and RifQreduced the secretion of prototypical inflammatory cytokines (TNF‐, IL‐6) and the burst ofoxidative stress in microglial cells activated with αS fibrillary aggregates. Note, however, that RifQwas constantly more efficacious than its parent compound in reducing microglial activation. Wealso established that the suppressive effects of Rif and RifQ on cytokine release was probably dueto inhibition of both PI3K‐ and non‐PI3K‐dependent signaling events. The control of oxidative stressappeared, however, essentially dependent on PI3K inhibition. Of interest, we also showed that RifQwas more efficient than Rif in protecting neuronal cells from toxic factors secreted by microgliaactivated by αS fibrils. Overall, data with RifQ are promising enough to justify further studies toconfirm the potential of this compound as an anti‐parkinsionian drug.Fil: Acuña, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Patología Experimental. Universidad Nacional de Salta. Facultad de Ciencias de la Salud. Instituto de Patología Experimental; Argentina. Sorbonne University; Francia. Centre National de la Recherche Scientifique; FranciaFil: Hamadat, Sabah. Sorbonne University; FranciaFil: Corbalan, Natalia Soledad. Université Paris Est Créteil; Francia. Universidad Nacional de Tucuman. Instituto de Investigaciones En Medicina Molecular y Celular Aplicada del Bicentenario. - Gobierno de la Provincia de Tucuman. Ministerio de Salud. Sistema Provincial de Salud. Instituto de Investigaciones En Medicina Molecular y Celular Aplicada del Bicentenario. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet Noa Sur. Instituto de Investigaciones En Medicina Molecular y Celular Aplicada del Bicentenario.; ArgentinaFil: González Lizarraga, Maria Florencia. Universidad Nacional de Tucuman. Instituto de Investigaciones En Medicina Molecular y Celular Aplicada del Bicentenario. - Gobierno de la Provincia de Tucuman. Ministerio de Salud. Sistema Provincial de Salud. Instituto de Investigaciones En Medicina Molecular y Celular Aplicada del Bicentenario. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet Noa Sur. Instituto de Investigaciones En Medicina Molecular y Celular Aplicada del Bicentenario.; ArgentinaFil: Dos Santos Pereira, Mauricio. Sorbonne University; Francia. Centre National de la Recherche Scientifique; Francia. Universidade de Sao Paulo; BrasilFil: Rocca, Jérémy. Sorbonne University; Francia. Centre National de la Recherche Scientifique; FranciaFil: Sepúlveda Díaz, Julia. Sorbonne University; Francia. Centre National de la Recherche Scientifique; FranciaFil: Del Bel, Elaine. Universidade de Sao Paulo; BrasilFil: Papy García, Dulce. Université Paris Est Créteil; FranciaFil: Chehin, Rosana Nieves. Universidad Nacional de Tucuman. Instituto de Investigaciones En Medicina Molecular y Celular Aplicada del Bicentenario. - Gobierno de la Provincia de Tucuman. Ministerio de Salud. Sistema Provincial de Salud. Instituto de Investigaciones En Medicina Molecular y Celular Aplicada del Bicentenario. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet Noa Sur. Instituto de Investigaciones En Medicina Molecular y Celular Aplicada del Bicentenario.; ArgentinaFil: Michel, Patrick P.. Sorbonne University; Francia. Centre National de la Recherche Scientifique; FranciaFil: Raisman Vozari, Rita. Sorbonne University; Francia. Centre National de la Recherche Scientifique; Franci

Functional and Structural Study of the Dimeric Inner Membrane Protein SbmA

SbmA protein has been proposed as a dimeric secondary transporter. The protein is involved in the transport of microcins B17 and J25, bleomycin, proline-rich antimicrobial peptides, antisense peptide phosphorodiamidate morpholino oligomers, and peptide nucleic acids into the Escherichia coli cytoplasm. The sbmA homologue is found in a variety of bacteria, though the physiological role of the protein is hitherto unknown. In this work, we carried out a functional and structural analysis to determine which amino acids are critical for the transport properties of SbmA. We created a set of 15 site-directed sbmA mutants in which single conserved amino acids were replaced by glycine residues. Our work demonstrated that strains carrying the site-directed mutants V102G, F219G, and E276G had a null phenotype for SbmA transport functions. In contrast, strains carrying the single point mutants W19G, W53G, F60G, S69G, N155G, R190, L233G, A344G, T255G, N308G, and R385G showed transport capacities indistinguishable from those of strains harboring a wild-type sbmA. The strain carrying the Y116G mutant exhibited mixed phenotypic characteristics. We also demonstrated that those sbmA mutants with severely impaired transport capacity showed a dominant negative phenotype. Electron microscopy data and in silico three-dimensional (3D) homology modeling support the idea that SbmA forms a homodimeric complex, closely resembling the membrane-spanning region of the ATP-binding cassette transporter family. Direct mapping of the sbmA single point mutants on the protein surface allowed us to explain the observed phenotypic differences in transport ability.Fil: Corbalan, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Runti, Giulia. Università degli Studi di Trieste; ItaliaFil: Adler, Conrado. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Covaceuszach, Sonia. Consiglio Nazionale delle Ricerche; ItaliaFil: Ford, Robert C.. University of Manchester; Reino UnidoFil: Lamba, Doriano. Consiglio Nazionale delle Ricerche; ItaliaFil: Beis, Konstantinos. Imperial College London; Reino UnidoFil: Scocchi, Marco. Università degli Studi di Trieste; ItaliaFil: Vincent, Paula Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

Inhibitory Effect of the Hybrid Bacteriocin Ent35-MccV on the Growth of Escherichia coli and Listeria monocytogenes in Model and Food Systems

Bacteriocins are being used as new food biopreservative agents. In general, bacteriocins produced by Gram-positive bacteria are active against other Grampositive. Basically, the same principle applies to those produced by Gram-negative bacteria. They have a restricted spectrum of action against related bacteria to those that produce the bacteriocin. Therefore, other hurdles or chemical preservatives are necessary to apply to broaden the spectrum of action of bacteriocins in foods. This is a further and deeper study of the possible application of the hybrid wide-spectrum bacteriocin named Ent35-MccV in food. Its antimicrobial activity was assayed in skim milk and patties as food models against Listeria monocytogenes and Escherichia coli. The influence of the temperature and digestive proteases on its biological activity and its antimicrobial activity was tested in vitro on a variety of pathogenic and food spoilage bacteria. The results showed that Ent35-MccV could inhibit the growth of both the Grampositive L. monocytogenes and the Gram-negative E. coli in model food, and its activity was not affected by heating conditions including autoclaving. E. coli strains and Listeria spp. are the most affected bacteria, but Ent35- MccV showed antimicrobial activity against some strain of Salmonella spp., Staphylococcus epidermidis, Enterobacter aerogenes, Morganella morgani, Proteus mirabilis, Shigella boydii, Shigella flexneri, and Shigella sonnei.Fil: Acuña, Leonardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Corbalan, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Fernandez No, Inmaculada C.. Universidad de Santiago de Compostela; EspañaFil: Morero, Roberto Dionisio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Barros Velázquez, Jorge. Universidad de Santiago de Compostela; EspañaFil: Bellomio, Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

The tolC locus affects the expression of sbmA through σE activity increase.

The SbmA protein is involved in the transport of MccB17-, MccJ25-, bleomycin- and proline-rich peptides into the Escherichia coli cytoplasm. sbmA gene homologues were found in a variety of bacteria. However, the physiological role of this protein still remains unknown. Previously, we found that a combination of sbmA and tolC mutations in Tn10-carrying E. coli K-12 strains results in hypersusceptibility to tetracycline. In this work, we studied sbmA expression in a tolC mutant background and observed an increased expression throughout growth. We ruled out the global transcriptional regulator RpoS and the small RNA micF as intermediates in this regulation. The tolC mutation induced the expression of other well-characterized strong σE- dependent promoters in E. coli. We observed that the increase in σE activity led to a greater sbmA expression, conversely eliminating σE prevented expression of sbmA. We also observed that the sbmA upregulation in a tolC mutant context was abolished in an rpoE-null strain. These results suggest a σE-dependent positive regulation on sbmA by the tolC mutation. We hypothesize that this mechanism might be part of a compensatory cell envelope stress response. © 2010 Federation of European Microbiological Societies.Fil: Corbalan, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Adler, Conrado. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: de Cristobal, Ricardo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Pomares, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Delgado, Monica Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Vincent, Paula Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

Enterobactin as part of the oxidative stress response repertoire

Microorganisms produce siderophores to facilitate iron uptake and even though this trait has been extensively studied, there is growing evidence suggesting that siderophores may have other physiological roles aside from iron acquisition. In support of this notion, we previously linked the archetypal siderophore enterobactin with oxidative stress alleviation. To further characterize this association, we studied the sensitivity of Escherichia coli strains lacking different components of the enterobactin system to the classical oxidative stressors hydrogen peroxide and paraquat. We observed that strains impaired in enterobactin production, uptake and hydrolysis were more susceptible to the oxidative damage caused by both compounds than the wild-type strain. In addition, meanwhile iron supplementation had little impact on the sensitivity, the reducing agent ascorbic acid alleviated the oxidative stress and therefore significantly decreased the sensitivity to the stressors. This indicated that the enterobactin-mediated protection is independent of its ability to scavenge iron. Furthermore, enterobactin supplementation conferred resistance to the entE mutant but did not have any protective effect on the fepG and fes mutants. Thus, we inferred that only after enterobactin is hydrolysed by Fes in the cell cytoplasm and iron is released, the free hydroxyl groups are available for radical stabilization. This hypothesis was validated testing the ability of enterobactin to scavenge radicals in vitro. Given the strong connection between enterobactin and oxidative stress, we studied the transcription of the entE gene and the concomitant production of the siderophore in response to such kind of stress. Interestingly, we observed that meanwhile iron represses the expression and production of the siderophore, hydrogen peroxide and paraquat favour these events even if iron is present. Our results support the involvement of enterobactin as part of the oxidative stress response and highlight the existence of a novel regulation mechanism for enterobactin biosynthesis.Fil: Peralta, Daiana Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Adler, Conrado. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Corbalan, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Paz García, Enrique Carlos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Pomares, Maria Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Vincent, Paula Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

Antimicrobial activity of MccJ25(G12Y) against gram-negative foodborne pathogens in vitro and in food models

The use of bacteriocins is a promising alternative to improve food security through the biocontrol of food pathogens and spoilage microorganisms. Gram-negative produced microcin J25(G12Y), known as (MccJ25(G12Y)) is a variant of the well-studied and characterized antimicrobial peptide, microcin J25 (MccJ25). In the present work, we explored the activity of this microcin against Gram-negative bacteria linked to foodborne diseases. We evaluated the in vitro antimicrobial activity of MccJ25(G12Y) in solid medium against a collection of pathogenic and food-altering strains and studied its activity and stability in meat and dairy food systems. We show that MccJ25(G12Y) exhibited the same in vitro antimicrobial spectrum as its parental microcin (MccJ25) against different Gram-negative foodborne pathogens and spoilage strains. We highlight that low concentrations of MccJ25(G12Y) between 0.45 and 29.4 μM were able to inhibit a substantial number of pathogens, including Salmonella, Escherichia, Shigella and Enterobacter genus. We also demonstrate the antimicrobial effectiveness of the peptide against Escherichia coli O157:H7 NCTC 12900, Enterobacter cloacae CECT 194, and Salmonella enterica CECT 4396 in fish and beef burgers and yogurt. MccJ25(G12Y) was added or not to food matrices inoculated with the foodborne pathogens at 105 CFU/g or mL. Afterward, food products were stored at 4 °C and selective media for the specific enumeration were used to determine the antimicrobial susceptibility of each pathogen to MccJ25(G12Y). The viability of the three pathogens was significantly reduced in the different food biological environments. In yogurt, the peptide decreased E. coli numbers on day 5 by about 4 log 10 CFU/mL as compared to non-treated samples. For S. enterica and E. cloacae no viable cells were detected at the end of the treatment. Adding MccJ25(G12Y) to fish burgers decreased E. cloacae numbers during storage 2 log10 CFU/g on the first day, reaching a difference of about 5 log 10 CFU/g after 10 days compared to non-treated control. Finally, the peptide decreased E. coli O157:H7 numbers on the beef burgers samples during storage on day 10 by about 3 log 10 CFU/g as compared to non-treated samples. The stability analysis demonstrated that MccJ25(G12Y) is capable of remaining active in these food matrices for a considerable time during the storage at refrigeration temperatures. These results reinforce the studies on the potential applicability of this microcin as a biopreservative in the food industry.Fil: Corbalan, Natalia Soledad. Universidad de Santiago de Compostela; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Quiroga, Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigaciones Agropecuarias. Unidad de Fitopatología y Modelización Agrícola - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Unidad de Fitopatología y Modelización Agrícola; ArgentinaFil: Masias, Ruth Emilse. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Peralta, Daiana Romina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Barros Velázquez, Jorge. Universidad de Santiago de Compostela; EspañaFil: Acuña, Leonardo. Universidad de Santiago de Compostela; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Patología Experimental. Universidad Nacional de Salta. Facultad de Ciencias de la Salud. Instituto de Patología Experimental; ArgentinaFil: Vincent, Paula Andrea. Universidad de Santiago de Compostela; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin

Canker Control by the Siderophore Pyochelin from Pseudomonas fluorescens.

This work shows the identification of a compound able to inhibit Xanthomonas citri subsp. citri (citrus canker agent) growth in vitro and in vivo. Firstly, we isolated from citrus leaves surfaces, bacteria able to inhibit X. citri subsp. citri in vitro. Among the selected isolates, we focused in one showing a remarkable activity. The strain was characterized as Pseudomonas fluorescens after sequencing its 16S rDNA and analyzing the sequence with BLASTn. Purification and chemical analysis of the active compound allowed us to assign the inhibitory activity to enantio-pyochelin (E-Pch). Since this molecule is a siderophore, we wondered if the inhibition observed was a result of iron scavenging. Surprisingly, when we supplemented media with an excess of iron, we observed practically no change in the inhibition activity. In an attempt to identify the action mechanism of E-Pch, we evaluated the ability of E-Pch to generate reactive oxygen species (ROS) within a culture of X. citri subsp. citri and its correlation with the inhibitory activity. In fact, we observed increased ROS levels when E-Pch was added. In addition, the reducer agent ascorbic acid, lowered ROS levels and the antibiotic activity, implying that inhibition is probably caused by oxidative stress. Finally, we studied the use of E-Pch in a model of canker disease. E-Pch showed to reduce canker formation on leaves of Eureka and Lisbon lemon cultivars. These results show E-Pch as a promising compound for citrus canker biocontrol.Fil: Adler, Conrado. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Michavila, Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Lopez, Fabian Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Corbalan, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Lami, María Jesús. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Filippone, María Paula. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Castagnaro, Atilio Pedro. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Vincent, Paula Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: de Cristobal, Ricardo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin