Endophytic yeast from sugarcane exhibit quorum quenching activity

Quorum sensing (QS) are signaling mechanisms that govern morphological and physiological responses to changes in cell density. QS enables microorganisms to communicate via secreted signaling molecules called autoinducers. Many of these autoninducers bellong to a N-acyl homoserine lactones`s (AHLs) family. AHLs are synthesized by Gram negative bacterias and their structure consist of a carbon N-acyl side chain linked to a lactone ring. These molecules are pH-dependent so the lactone ring will be reversibly hydrolyzed. On the other hand, Quorum quenching (QQ) is a process which disrupts the QS by different ways such as enzymatic lysis of the signal molecules. QQ allows to control many physiological mechanisms from pathogen gram negative bacteria. In view of this, the aim of the present work was to isolate yeasts with QQ properties from Saccharum officinarum, a species of sugar cane. Samples from roots, stems and leaves were plated onto YM agar. Incubation was carried out at 30ºC. Colonies with different morphotypes were selected and plated. Pure colony was obtained by repeated streaking on YM agar. The genomic DNA of the yeast isolates were extracted to identify them. They were used as template for PCR. The 26S rDNA gene was PCR-amplified using the following primers namely NL1 and NL4. Nucleotide sequences were compared with GenBank databases using the BLASTN program followed by sequence alignment Yeasts were incubated onto YM supplemented with HSLs comercial standards (C6-HSL, 3-oxo-C6-HSL, C10-HSL, 3-oxo-C10-HSL, C12-HSL, 3-oxo-C12-HSL, C8-HSL and 3-oxo-C8-HSL) to demostrate the presence of QQ mechanisms. After 2 days incubation supernadants of cultures were taken and the detection of HSLs degradation was carry out using two biosensor strains, Chromobacterium violaceum CV026 and Chromobacterium violaceum Vir07. If necessary acidification for re-lactonisation using HCl was performed. 19 yeast strains were finally isolated. Sequencing of 26S rDNA indicated that 19 strains bellonged to three different genus (Pichia, Rhodotorula and Sporisorium). In the QQ assay, all yeasts tested were able to degradate at least one of the proven HSLs comercial standards. The isolates presented a marked tendecy to hidrolyse long-acyl-chain compounds. However, two Rhodotorula strains exhibited the most outstanding behavior, by degradating the 8 different QS molecules assayed. In order to demostrate lactonase activity, supernadants of cultures were adicionated with HCl. The following bioassays revealed that at low pH levels the lactone rings were closed again suggesting the presence of lactonase enzymes in Rhodotorula yeasts.Fil: Bertini, Elisa Violeta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Leguina, Ana Carolina del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Nieto Peñalver, Carlos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaX Congreso Argentino de Microbiología GeneralMar del PlataArgentinaSociedad Argentina de Microbiología Genera

Towards the design of stable and effective dye-decolorizing consortia of edible fungi

Synthetic dyes are used in textile industries due to their advantages over natural dyes. However, textile effluents cause irreparable damageto water bodies because of the proper toxicity of textile dyes or by reducing the penetration of visible light leading to the eutrophicationrivers and lakes. Aerobic biodecoloration is an interesting treatment alternative for these effluents. However, no microorganism is capableof degrading all existing dyes, making the use of microbial consortia mandatory. Wood White Rot fungi produce enzymes such as Laccase,Manganese Peroxidase or Lignin Peroxidase that have been widely used for the degradation of textile dyes. The objective of this work wasthe selection of compatible edible fungi for the formation of consortiums capable of degrading different colorants. For this, we selected tenPleurotus, Psilocybe, Ganoderma and Lentinula strains. Fungi were maintained in Petri dishes with 20 mL of solid YM medium (glucose:1%, soy peptone: 0.5%, yeast extract: 0.3%, malt extract: 0.3%, agar: 1.8%), incubated at 25°C. Media were inoculated with 5 mm diameterplugs obtained from growths in solid YM medium, preincubated for 7 days at 25°C. The laccase production of the different fungi wasevaluated in solid media using eight substrates: 2,2-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), catechol, 2,6-dimethoxyphenol, 1-naphthol, benzidine, syringaldazine, 3,4-dimethoxybenzylalcohol, and guaiacol. Assays in which oxidized substratesproduced haloes of different colors around the wells were considered positive. To carry out the compatibility tests, the ten strains wereconfronted with each other on different plates with YM solid medium in duplicate and incubated for 7 days at 25°C. Four modes ofinteraction were observed: inhibition haloes, zone with a dark line (in the contact of one strain with the other the line is produced),overgrowth (invasion of one strain on the other) and growth without inhibition. For the evaluation of the bleaching capacity of each strain,four industrial textile dyes were used: Black Vilmafix® B-V, Blue Vimafix® RR-BB, Red Vilmafix® 7B-HE and Orange Procion® HER,which were seeded in four wells made in the plates of each strain forming halos of each color. After 24 hours of incubation at 25°C,different levels of degradation were observed around the haloes depending on the structure of the dye. The results show that the testedfungi could be employed in the design of effective dye decolorizing consortia.Fil: Dominguez, Facundo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Pacheco, Mariana Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Torres, Mariela Analía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Nieto Peñalver, Carlos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Pajot, Hipolito Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaXL Reunión Científica Anual de la Sociedad de Biología de CuyoMendozaArgentinaSociedad de Biología de Cuy

Multi-Focused Laboratory Experiments Based on Quorum Sensing and Quorum Quenching for Acquiring Microbial Physiology Concepts

After a time away from the classrooms and laboratories due to the global pandemic, the return to the teaching activities during the semester represented a challenge to both teachers and students. Our particular situation in a Microbial Physiology course was the necessity of imparting in a shorter time, laboratory practices that usually take longer. This article describes a two-week long laboratory exercise that covers several concepts in an interrelated way: conjugation as a gene transfer mechanism, regulation of microbial physiology, production of secondary metabolites, degradation of macromolecules and biofilm formation. Utilizing a Quorum Quenching (QQ) strategy, the Quorum Sensing (QS) system of Pseudomonas aeruginosa is first attenuated. Then, phenotypes regulated by QS are evidenced. QS is a regulatory mechanism of the microbial physiology that relays on signal molecules. QS is related in P. aeruginosa to several virulence factors, some of which are exploited in the laboratory practices presented in this work. QQ is phenomenon by which QS is interrupted or attenuated. We utilized a QQ approach based on the enzymatic degradation of the P. aeruginosa QS signals in order to put in evidence QS-regulated traits that are relevant for our Microbial Physiology course.Fil: Torres, Mariela Analía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Valdez, Alejandra Leonor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Olea, Carolina de Lourdes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Nieto Peñalver, Carlos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin

Detection of acylhomoserine lactones in cultures of Gluconacetobacter diazotrophicus PAL5

Gluconacetobacter diazotrophicus is an acid-tolerant nitrogen- fixing Alphaproteobacterium first found in association with sugarcane. It has also been isolated from rice, coffee and tea, among others crops. The recent sequencing of the G. diazotrophicus PAL5 genome shows the presence of one luxI homolog. These genes encode LuxI-type enzymes responsible for the synthesis of N- acylhomoserine lactones (AHLs), the main quorum sensing molecules in gram negative bacteria. The objective of this work was the detection and identification of AHLs produced by G. diazotrophicus PAL5. The strain was cultured aerobically, and extracts were prepared with acidified ethyl acetate. Samples were analyzed by thin layer chromatography developed with the biosensor Agrobacterium tumefaciens NTL4 (pCF218) (pCF372). Results show that G. diazotrophicus PAL5 produce at least two types of AHLs under the assayed conditions. Short-chain AHLs could be detected since early exponential growth phase, and medium-chain AHLs were detected in mid- and late-exponential growth phase. The results suggest that the luxI homolog in G. diazotrophicus PAL5 is expressed and quorum sensing molecules are produced and secreted. Similar to other bacteria, production of AHLs in G. diazotrophicus PAL5 could serves as a signaling mechanism among members of this genus or as inter kingdom signals.Fil: Nieto Peñalver, Carlos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Bichara, Laura Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Marino, Damian Jose Gabriel. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigaciones del Medio Ambiente - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones del Medio Ambiente; ArgentinaFil: Castellanos, Lucia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Irazusta, Verónica Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaXLVI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología MolecularPuerto MadrynArgentinaSociedad Argentina de Investigación en Bioquímica y Biología Molecula

Propionibacterium acidipropionici CRL1198 influences the production of acids and the growth of bacterial genera stimulated by inulin in a murine model of cecal slurries

Different attempts have been made to improve the health status of humans and animals by increasing the intestinal production of short-chain fatty acids (SCFA) derived from non-digestible carbohydrates fermentation. In this paper we investigate the in vitro production of short-chain fatty acids (SCFA) after addition of inulin, propionibacteria or a combination of both in an experimental model of mice cecal slurries. The development of bacterial genera which are usually stimulated by inulin addition was also investigated. According to our experimental data, acetic acid and butyric acids concentrations increased after incubation in slurries that had no supplements. By contrast, butyric acid concentrations remained in the basal value when supplements were used. Fermentation of only inulin did not increase the concentration of total SCFA. Propionibacterium acidipropionici CRL1198 improved the production of propionic acid in cecal slurries when it was added alone, but the effect was more noticeable in the combination with inulin. A modulation of the global fermentative activity of the cecal microbiota was evidenced by the increase on the ratio propionic acid/SCFA in supplementations with propionibacteria. Statistical analysis of data demonstrated that samples from homogenates with propionibacteria alone or combined with inulin belong to the same cluster. The presence of propionibacteria limited the growth of Bacteroides fragilis and Clostridium hystoliticum groups in slurries with and without inulin. The growth of Bifidobacterium was not modified and the stimulating effect of inulin on lactobacilli disappeared in the presence of propionibacteria. In conclusion, dairy propionibacteria are potential candidates to develop new functional foods helpful to ensure the intestinal production of SCFA during inulin supplementation and to control the overgrowth of bacteria belonging to Bacteroides and Clostridium genera.Fil: Lorenzo Pisarello, Maria Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Gultemirian, Maria de Lourdes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Nieto Peñalver, Carlos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; ArgentinaFil: Perez Chaia, Adriana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentin

Proteomic and physiological characterization of copper effect on quorum sensing regulation in Pseudomonas capeferrum

Copper has largely been used for the control of phytopathogen fungi in agriculture, even though to its non-degradability, it tends to accumulate in soils reaching prejudicial levels for soil microorganisms, including rhizomicroorganisms. The rhizosphere is characterized by intense and complex interactions that take place in it. Many of these intra- and interspecies interactions occur through quorum sensing (QS) systems. QS is a cell-to-cell signaling mechanism that control the microbial physiology in a population density manner. Several soil bacteria use QS circuits to regulate important phenotypes. In this work we studied the influence of copper on QS regulation in the plant growth-promoting rhizobacterium (PGPR) Pseudomonas capeferrum WCS358. Firstly, the QS system of the bacterium was inactivated using a quorum quenching strategy. Secondly, intracellular proteins of Ps. capeferrum WCS358 QS+ and QS-, cultured in the presence or absence of copper, were analyzed using liquid chromatography coupled to mass spectrometry. Furthermore, the effects of copper and QS on other activities such us motility, biofilm production and oxidative stress response were also evaluated in Ps. capeferrum WCS358. The QS activity and the presence of metal modified the relative abundance of proteins involved in amino acid and carbohydrate metabolism, oxidative stress defense and nutrient absorption. Besides, results indicated that QS system is implicated in the regulation of motility, biofilm production and oxidative stress response in Ps. capeferrum WCS358 and that copper had a negative effect on these activities. The results presented in this work indicate that QS regulates important traits in Ps. capeferrum WCS358 and that contamination with copper could be detrimental for the QS-dependent phenotypes in this rhizobacterium. Since the modifications observed are related to activities that are significant for the survival and fitness of bacteria, they suggest that QS may confer a competitive advantage to Ps. capeferrum WCS358 and that copper could alter the competence of this PGPR in its natural niche.Fil: Leguina, Ana Carolina del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Lacosegliaz, Mariano José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Fernández, Pablo Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Castellanos, Lucia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Nieto Peñalver, Carlos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaLVI Annual Meeting Argentine Society for Biochemistry and Molecular Biology and XV Annual Meeting Argentinean Society for General MicrobiologyCiudad Autónoma de Buenos AiresArgentinaSociedad Argentina de Investigación Bioquímica y BiologíaSociedad Argentina de Microbiología Genera

Vinasse as a substrate for inoculant culture and soil fertigation: Advancing the circular and green economy

Vinasse is a by-product with a key role in circular economy. In this work, we analyze sugarcane vinasse as culture medium for obtaining single and mixed inoculants. Trichoderma harzianum MT2 was cultured in single and sequential co-culture with Pseudomonas capeferrum WCS358 or Rhizobium sp. N21.2. Fungal biomass in single culture was more than three folds higher in vinasse than in a standard medium, and was higher in co-culture with Rhizobium sp. N21.2 than with P. capeferrum WCS358. Bacterial growths in vinasse, in particular P. capeferrum WCS358, were improved in co-culture with T. harzianum MT2. Residual vinasses, obtained after microbial growth, presented almost neutral pH and lower conductivities and toxicity than raw vinasse. Fertigation with residual vinasses modifies characteristics of soil evidenced in the total N, cation exchange capacity, urease and acid phosphatase, and microbial metabolic diversity, in comparison to raw vinasse. In general, soil fertigation with residual vinasse from co-culture with P. capeferrum WCS358 is more similar to irrigation with water. Treatment evaluation indicates that vinasse is suitable for the production of mixed inoculants containing T. harzianum. The co-culture with P. capeferrum WCS358 improves the characteristics of the residual vinasse allowing a fertigation with less detrimental effect in soil in comparison to Rhizobium sp. N21.2. Obtaining valuable biomass of single or mixed inoculants in vinasse with lower ecological impact is relevant for the circular and green economy.Fil: Torres, Mariela Analía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Valdez, Alejandra Leonor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Angelicola, María Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Raimondo, Enzo Emanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Física; ArgentinaFil: Pajot, Hipolito Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Nieto Peñalver, Carlos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología; Argentin

Cultivation of plant-growth promoters in vinasse: contributions for a circular and green economy

Vinasse is a by-product with a key role in the circular economy. In this work, we analyze sugarcane vinasse as culture medium for obtaining single and mixed inoculants. Trichoderma harzianum was cultured in single and sequential co-culture with Pseudomonas capeferrum or Rhizobium sp. Fungal biomass was higher in vinasse than in a laboratory medium. Residual vinasses presented almost neutral pH and lower conductivities and toxicity than raw vinasse. Fertigation with residual vinasses improves characteristics of soil evidenced in the total N, cation exchange capacity, urease and acid phosphatase, and the microbial metabolic diversity, in comparison to raw vinasse. The evaluation of the treatment indicates that vinasse is suitable for the production of inoculants containing T. harzianum and that the co-culture with P. capeferrum improves the characteristics of the residual vinasse in comparison to Rhizobium sp. Obtaining this valuable biomass in vinasse is relevant for the circular and green economy.Fil: Torres, Mariela Analía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Valdez, Alejandra Leonor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Angelicola, María Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Raimondo, Enzo Emanuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Pajot, Hipolito Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Nieto Peñalver, Carlos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia; Argentin

ß-lactamasas AmpC plasmídicas tipo CMY-2 emergentes en Tucumán, Argentina

En los últimos años, algunas enterobacterias como Klebsiella pneumoniae, Proteus mirabilis y Escherichia coli adquirieron resistencia a las cefalosporinas de tercera generación (C3G) por la adquisición de ß-lactamasas de tipo AmpC plasmídicas, mecanismo que se está comunicando cada vez con mayor frecuencia en el mundo. El objetivo de esta investigación fue detectar la emergencia de ß-lactamasas AmpC plasmídicas en Tucumán e identificar sus tipos predominantes. Se estudió la sensibilidad a diferentes antimicrobianos de 733 aislamientos clínicos consecutivos de enterobacterias obtenidos en el período marzo-julio de 2009 en tres centros asistenciales de nuestra provincia. Se realizaron pruebas de sensibilidad por difusión y se seleccionaron tres aislamientos de E. coli y uno de P. mirabilis resistentes a C3G y a cefoxitina. En estos aislamientos se determinó la CIM por E-test y se evaluó el mecanismo enzimático de resistencia mediante sinergia con discos de ácido aminofenilborónico y ensayo microbiológico de Masuda. Se realizó PCR usando cebadores dirigidos al grupo CIT de las AmpC plasmídicas. Se obtuvo un amplicón de 462 pb que fue secuenciado; presentó un 100% de identidad con blaCMY-2 en los cuatro aislamientos. En conclusión, las ß-lactamasas AmpC tipo CMY-2 emergieron en nuestro medio, de modo que es importante implementar una vigilancia sistemática de estas resistencias para evitar potenciales consecuencias clínicas y epidemiológicas.CMY-2-type plasmid-mediated AmpC B-Lactamases emerging in Tucumán, Argentina. In the last years, Enterobacteriaceae such as Klebsiella pneumoniae, Proteus mirabilis and Escherichia coli, have acquired resistance to third-generation cephalosporins (C3G) because of the presence of plasmid-mediated AmpC B-lactamases. The aim of this work was to detect plasmid AmpC enzymes and to investigate the predominant types in our region. Between March and July 2009, 733 consecutive isolates of Enterobacteriaceae derived from hospitals and outpatient centers were studied. Susceptibility testing was performed by disk diffusion; one P. mirabilis and three E. coli strains showed resistance to cephamycins (cefoxitin) and C3G. An E-test to determine MIC and a synergy test by aminophenylboronic disks were performed. Enzymatic activity against cefoxitin was confirmed by a microbiological assay. A polymerase chain reaction (PCR) for the detection of plasmid-mediated ampC genes of different groups was performed and a 462-bp amplicon was obtained when using primers directed against the CIT group; the obtained sequences were compared to blaCMY-2 sequences, showing 100% identity. The emergence of CMY-2-type plasmid-mediated AmpC B-lactamases indicated the importance of implementing systematic monitoring of these resistances to avoid potential clinical and epidemiological consequences.Fil: Jure, Maria Angela. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología "Luis Verna". Cátedra de Bacteriología; ArgentinaFil: Presti, Constanza. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología "Luis Verna". Cátedra de Bacteriología; ArgentinaFil: Cudmani, Norma M.. Hospital Avellaneda. Laboratorio de Bacteriología; ArgentinaFil: Grellet, Lidia M.. Pcia. de Tucumán. Hospital de Concepción; ArgentinaFil: López, Carolina. Centro de Microbiología Médica. Laboratorio de Bacteriología; ArgentinaFil: Musa, Eduardo H.. Centro de Microbiologia. Red WHONET, San Miguel de Tucumán; ArgentinaFil: Aulet, Olga C.. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología "Luis Verna". Cátedra de Bacteriología; ArgentinaFil: Nieto Peñalver, Carlos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología "Luis Verna". Cátedra de Bacteriología; ArgentinaFil: Saavedra, Maria Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: de Castillo, Marta Cecilia. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Microbiología "Luis Verna". Cátedra de Bacteriología; Argentin

Insight in the quorum sensing-driven lifestyle of the non-pathogenic Agrobacterium tumefaciens 6N2 and the interactions with the yeast Meyerozyma guilliermondii

Agrobacterium tumefaciens is considered a prominent phytopathogen, though most isolates are nonpathogenic. Agrobacteria can inhabit plant tissues interacting with other microorganisms. Yeasts are likewise part of these communities. We analyzed the quorum sensing (QS) systems of A. tumefaciens strain 6N2, and its relevance for the interaction with the yeast Meyerozyma guilliermondii, both sugarcane endophytes. We show that strain 6N2 is nonpathogenic, produces OHC8-HSL, OHC10-HSL, OC12-HSL and OHC12-HSL as QS signals, and possesses a complex QS architecture, with one truncated, two complete systems, and three additional QS-signal receptors. A proteomic approach showed differences in QS-regulated proteins between pure (64 proteins) and dual (33 proteins) cultures. Seven proteins were consistently regulated by quorum sensing in pure and dual cultures. M. guilliermondii proteins influenced by QS activity were also evaluated. Several up- and down- regulated proteins differed depending on the bacterial QS. These results show the importance of the QS regulation in the bacteria-yeast interactions.Fil: Bertini, Elisa Violeta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Torres, Mariela Analía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Leger, Thibaut. Institut Jacues Monod; FranciaFil: Garcia, Camille. Institut Jacques Monod; FranciaFil: KarWai, Hong. University Of Malaya; MalasiaFil: Teik Min, Chong. University Of Malaya; MalasiaFil: Castellanos, Lucia Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: KokGan, Chan. University Of Malaya; MalasiaFil: Dessaux, Yves. Universite Paris-sud; FranciaFil: Camadro, Jean Michel. Institut Jacques Monod; FranciaFil: Nieto Peñalver, Carlos Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin