Variación diurna de la composición bacterioplanctónica y daño en el ADN de la comunidad microbiana de una laguna oligotrófica de los Andes

La Laguna Azul es un ambiente oligotrófico localizado a 4560 m de altura y sometido a elevados niveles de radiación solar. La composición de su comunidad bacterioplanctónica fue analizada empleando la técnica de electroforesis en gradiente desnaturalizante y se investigó el impacto de la radiación ultravioleta cuantificando los dímeros de pirimidina (CPD). Además, se expusieron simultáneamente cultivos puros de Acinetobacter johnsonii A2 y Rhodococcus sp. A5 para estudiar la acumulación de CPD. El análisis de los geles mostró siete secuencias pertenecientes a Alpha-proteobacteria (1 banda), Beta-proteobacteria (1 banda), Bacteroidetes (2 bandas), Actinobacteria (1 banda) y Firmicutes (1 banda). A lo largo del día se observaron cambios mínimos en la composición de la comunidad y no se detectaron CPD. A. johnsonii A2 presentó un daño bajo mientras que Rhodococcus sp. A5 no presentó daño en su ADN, sugiriendo que la comunidad bacteriana está muy bien adaptada a este ambiente altamente irradiado.Laguna Azul is an oligotrophic lake situated at 4,560 m above sea level and subject to a high level of solar radiation. Bacterioplankton community composition (BCC) was analysed by denaturing gradient gel electrophoresis and the impact of solar ultraviolet radiation was assessed by measuring cyclobutane pyrimidine dimers (CPD). Furthermore, pure cultures of Acinetobacter johnsonii A2 and Rhodococcus sp. A5 were exposed simultaneously and CPD accumulation was studied. Gel analyses generated a total of 7 sequences belonging to Alpha-proteobacteria (1 band), Beta-proteobacteria (1 band), Bacteroidetes (2 bands), Actinobacteria (1 band), and Firmicutes (1 band). DGGE profi les showed minimal changes in BCC and no CPD was detected even though a high level of damage was found in biodosimeters. A. johnsonii A2 showed low level of DNA damage while Rhodococcus sp. A5 exhibited high resistance since no CPD were detected under natural UV-B exposure, suggesting that the bacterial community is well adapted to this highly solar irradiated environment.Fil: Fernandez Zenoff, Maria Veronica. 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; ArgentinaFil: Estévez, Maria Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin

Diatom and Invertebrate Assemblages in High Altitude Saline Wetlands of the Argentinian Puna and their Relation to Environmental Factors

Aquatic biota in high altitude Andean wetlands is exposed to extreme environmental conditions that influence ecological parameters at population and community levels. We analyzed changes in occurrence, taxa richness and relative abundance of diatom and invertebrate assemblages in four saline wetlands located at the same altitude (approx. 3,330 masl), in the Salar de Antofalla (Catamarca, Argentina). Biological samples were taken seasonally during a 1-year period, together with water variables, which were used in ordination techniques to characterize the sites. Water ionic content and biological variables, such as microcrustacean abundance and diatom richness, were evaluated as possible factors affecting the assemblages’ distribution. The wetlands ranged from meso- to hyperhaline habitats and showed distinctive morphological, physical and chemical characteristics. Diatoms (42 taxa) and invertebrates (15 taxa) were collected from all sites, and diatom taxa richness was negatively correlated with water conductivity. According to multivariate analysis, the distribution of both communities was significantly explained by water hardness, whereas copepod abundance also influenced the diatom flora. We conclude that, at the same altitude and, consequently, UV radiation exposure, variables related to ionic content and/or biological parameters of the aquatic habitat may act as determinants of the biota distribution in these extreme environments.Fil: Colla, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Catamarca. Universidad Nacional de Catamarca. Centro de Investigaciones y Transferencia de Catamarca; ArgentinaFil: Lencina, Agustina Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Catamarca. Universidad Nacional de Catamarca. Centro de Investigaciones y Transferencia de Catamarca; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin

UV Resistance and Photoreactivation of Extremophiles from High-Altitude Andean Lakes

He HAAL are natural laboratories for exploring and monitoring in situ interactions between the geophysical environment and the dynamics of biodiversity. Solar irradiation (including high UV-B doses) is without doubt the factor that puts the greatest pressure on the ecology of the microbial communities thriving in these shallow lakes. Thus, it is not surprising that ~100 strains with intrinsic UV-B-resistance have been isolated from HAAL. These organisms have developed strategies to cope with strong UV-B irradiation to avoid severe UV-B-damage to proteins, lipids and DNA. Hence, microbiota at the HAAL may harbor special mechanisms to sense and respond to such a ubiquitous resource, i.e., light. In accordance with this, we have encountered a rich diversity of photoreceptors within the cryptochrome-photolyase family in the genomes of three UV-B-resistant extremophiles. Of particular importance among these photoreceptors was the finding of a photolyase-coding sequence in the genome of Acinetobacter sp. Ver3 strain that displayed efficient photoreactivation ability after strong UV-B-induced DNA damage. Based on sequence alignments and secondary structure predictions for this novel photolyase, and entries in the PDB, we found the highest three-dimensional similarity to the photolyase from E. coli (PDB 1DNPA). The structure revealed a proximal alpha-beta domain, and a distal helical domain that binds to FAD in full accordance to the structure of the E. coli photolyase. The N-terminal anti-parallel bundle of beta sheets enclosed by alpha helices is a typical folding motif of photolyases. The chain of three-tryptophan residues instrumental for electron transfer reaction is also conserved in Ver3 photolyase, and in close proximity to the isoalloxazine ring of FAD. All the former findings support the putative CPD-photolyase property of this protein, and agree with the efficient ability of Ver3 for repairing CPD lesions. Nevertheless, a more detailed functional characterization of this "extremoenzyme" is being conducted at the moment to clarify its repair function. The scenario pictured herein makes the HAAL microorganisms excellent test cases for exploring novel enzymatic functions driven by light, and for the bioprospection of novel molecules with potential biotechnological applications on energy conversion, biomedicine or industry. This brief overview is intended to "shine" scientific light on a high window from a quite unexplored, exotic environment, which otherwise constitutes an exceptional outdoor photobiology lab.Fil: Albarracín, Virginia Helena. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina. Max Planck Institute for Chemical Energy Conversion; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Gärtner, Wolfang. Max Planck Institute for Chemical Energy Conversion; AlemaniaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin

Isolation and characterization of plant growth promoting bacteria isolated from andean soil as potential inoculants of soybean seeds

Argentina is the leading exporter of soybean oil and flour, and the third largest producer of grain. Since, the crop isa matter of great importance to the national economy. Their production depends on the soil as their main resourceto ensure a good productive capacity, so it is necessary to preserve the physical, chemical and biological propertiesof the soil. Although, the indiscriminate use of chemical fertilizers, disturb them. In recent years, there has been atrend towards cleaner production to reduce the use of chemical. One of the alternatives involves biological meansthrough the use of plant growth promoting bacteria. These group of bacteria colonize the rhizosphere of plants andstimulate the plant growth by several mechanisms.The objective of this work was to characterize, identify and evaluate the growth promoting effect of 13 strainsisolated from the Andean vegetation rhizosphere. The bacterial isolates were Enterobacteria, Stenotrophomonas,Pseudomonas, Nocardiodes, Bacillus, Exiguobacterium, Acinetobacter and Lactococcus genera. The results of thebiochemical characterization determined that from the 13 bacterial strains, which produce siderophores, 11possess the catalase enzyme, 10 fixate nitrogen, 12 produce the protease enzyme, 12 solubilize phosphorus, and 11produce indoleacetic acid.The application of different inoculums to the seeds, allowed to obtain plants with longer stem length, moredeveloped roots, larger and more intense coloration leaves than the control plants. The results encourage deeperstudies to achieve the formulation of inoculums to use as a biofertilizer, which would replace chemical fertilizersor reduce their doses.Fil: Belfiore, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Santos, Ana Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin

The antibacterial action of microcin J25: evidence for disruption of cytoplasmic membrane energization in Salmonella newport

Microcin J25 (MccJ25) is a cyclic peptide of 21 unmodified amino acid residues produced by a fecal strain of Escherichia coli. It has previously been shown that the antibiotic activity of this peptide is mainly directed to Enterobacteriaceae, including several pathogenic E. coli, Salmonella and Shigella strains. In this paper we show that MccJ25 acts on the cytoplasmic membrane of Salmonella newport cells producing alteration of membrane permeability, and the subsequent gradient dissipation, that initiate the inhibition of process, such as oxygen consumption. These results, taken together with our in vitro observations [Rintoul et al. (2000) Biochim. Biophys. Acta 1509, 65–72], strongly suggest that the disruption of the cytoplasmic membrane gradient is closely related to the bactericidal activity of MccJ25 in S. newport.Fil: Rintoul, Maria Regina. 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: Fernandez, Beatriz Eugenia. 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: Salomon, Raul Armando. 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: Farias, Ricardo Norberto. 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: Morero, Roberto Dionisio. 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

Extreme-halophiles: their role in the arsenic biogeochemical cycle

Biofilms, mats and microbialites dwell under extreme environmental conditions (high salinity, extreme aridity, pH and arsenic concentration) in the Argentinean Puna and the Atacama Desert. Microbial communities inhabiting those ecosystems are poorly known. Arsenic metabolism is proposed to be an ancient mechanism in microbial life. Besides, some bacteria and archaea are not only able to use detoxification processes to grow under high arsenic concentration, but also, some of them are able to exploit arsenic as a bioenergetic substrate in either anaerobic arsenate respiration or chemolithotrophic growth on arsenite. Only four aioAB coding for arsenite oxidase and two arrA coding for arsenate reductase sequences from haloarchaea were previously deposited in the NCBI Database, but have not been reported in the literature. The arrA arsenate reductases are reliable indicators of anaerobic As (V) respiration and catalyze the electron transfer to the As (V) terminal acceptor in dissimilatory arsenatereducing prokaryotes (DARPs). In this work, we are presenting our first steps in the study of the arsenic biogeochemical cycle in these ecosystems. Thus, the aim of this study was to isolate and to study the arsenic metabolism genes of the isolated extreme halophile microorganisms as well as to test the growth in minimal medium using different carbon sources. Mats and microbialites samples were taken from the water’s edge of Laguna Tebenquiche, Laguna Brava (Salar de Atacama, Chile) during December 2012 and from gaylusite crystals (Laguna Diamante) in August 2014. Samples were enriched and plated in WS medium supplemented with arsenic (AsIII 0.5mM and AsV 20mM). Arsenite oxidase (aioB) and Arsenate reductase (arrA) primers specific for haloarchaea were designed using PrimerProspector software. Selected primers were aioB-1190F (5’-GCTCMTSACCGGCAGCGTCG-3’), aioB-1507R (5’-YGATCTCGTCGATGTCGGCG-3’), arrA-417F (5’CCCGAGTTCGAGCCSATCTC-3’) and arrA-614R (5’GCRCAGATCGMGCTGTGGGA-3’). In order to identify the isolates we used Archaea-specific primers for 16S rDNA gene amplification: 344F (5´- ACG GGG YGC AGC AGG CGC GA-3´) and 915R (5´- GTG CTC CCC CGC CAA TTC CT -3´). Fragments of 577 bp, 317pb and 197pb were obtained from 16S rDNA, aioB and arrA genes respectively. Universal primers 27F and 1492R were used to amplify 16S rDNA in bacterial isolates. 25 isolates belonging to Archaea and Bacteria Domain were obtained; they are related to the Phylum Euryarchaeota, Firmicutes and Proteobacteria. AioB and arrA genes were found in most of the isolates and DNA from the samples (mats, microbialites and biofilm). The best carbon source tested was pyruvate and acetate, being pyruvate better in all cases. Promising results were obtained in the search of organisms able to use arsenic in their bioenergetic metabolism. More studies are underway to try to better understand these very interesting systems.Fil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Ordoñez, Omar Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Soria, Mariana Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaXI Congreso Argentino de Microbiología GeneralCordobaArgentinaSociedad Argentina de Microbiología Genera

Uncovering Photolyase/Cryptochrome Genes Diversity in Aquatic Microbiomes Exposed to Diverse UV-B Regimes

During evolution, microorganisms exposed to high UV-B doses developed a fine-tuned photo-enzymes called ?photolyases? to cope with DNA damage by UV-B. These photoreceptors belonging to the Cryptochrome/Photolyase Family (CPF) were well characterized at the genomic and proteomic level in bacteria isolated from a wide range of environments. In this work, we go further towards studying the abundance of CPF on aquatic microbial communities from different geographic regions across the globe. Metagenomics data combined with geo-referenced solar irradiation measurements indicated that the higher the UV-B dose suffered by the microbiome´s environment, the higher the abundance of CPF genes and lower the microbial diversity. A connection between CPF abundance and radiation intensity/photoperiod was reported. Likewise, cryptochrome-like genes were found abundant in most exposed microbiomes, indicating a complementary role to standard photolyases. Also, we observed that CPFs are more likely present in dominant taxa of the highly irradiated microbiomes, suggesting an evolutionary force for survival and dominance under extreme solar exposure. Finally, this work reported three novel CPF clades not identified so far, proving the potential of global metagenomic analyses in detecting novel proteins.Fil: Alonso Reyes, Daniel Gonzalo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Albarracín, Virginia Helena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin

Strategies and approaches in plasmidome studies, uncovering plasmid diversity disregarding of linear elements?

The term plasmid was originally coined for circular, extrachromosomal genetic elements. Today, plasmids are widely recognised not only as important factors facilitating genome restructuring but also as vehicles for the dissemination of beneficial characters within bacterial communities. Plasmid diversity has been uncovered by means of culture dependent or independent approaches, such as endogenous or exogenous plasmid isolation as well as PCR-based detection or transposon-aided capture, respectively. High-throughput-sequencing made possible to cover total plasmid populations in a given environment, i.e. the plasmidome, and allowed to address the quality and significance of self-replicating genetic elements. Since such efforts were and still are rather restricted to circular molecules, here we put equal emphasis on the linear plasmids which despite their frequent occurrence in a large number of bacteria are largely neglected in prevalent plasmidome conceptions.Fil: Dib, Julian Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Planta Piloto de Procesos Industriales Microbiologicos; ArgentinaFil: Wagenknecht, Martin. Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster.; AlemaniaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucuman. Planta Piloto de Procesos Industriales Microbiologicos; ArgentinaFil: Meinhardt, Friedhelm. Institut für Molekulare Mikrobiologie und Biotechnologie, Westfälische Wilhelms-Universität Münster, Münster.; Alemani

Diseño experimental para la evaluación de perfiles de resistencia UV y habilidades de fotorreparación en extremófilos

Se evaluarán los perfiles de resistencia a UV y capacidad fotorreparadora de cepas de interés aisladas de lagunas de altura puno-andinas (LAPAs) empleando como organismo modelo Acinetobacter sp. Ver3. Además, utilizaremos herramientas bioinformáticas para obtener en bases de datos los genes codificantes para fotoliasas. De esta manera se podrán diseñar oligonucleótidos específicos para las reacciones de PCR para la detección de genes en el genoma de cepas extremófilas.Fil: Albarracín, Virginia Helena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Planta Piloto de Procesos Industriales Microbiológicos (i); Argentina. Universidad Nacional de Tucumán; Argentina. Max-Planck Institut für Chemische Energie Konversion; AlemaniaFil: Moreno, Julio Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Planta Piloto de Procesos Industriales Microbiológicos (i); Argentina. Universidad Nacional de Tucumán; ArgentinaFil: Gärtner, Wolfang. Max-Planck Institut für Chemische Energie Konversion; AlemaniaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Planta Piloto de Procesos Industriales Microbiológicos (i); Argentin

The biofilms formation of exiguobacterium sp. S17 on synthetic supports and under the influence of arsenic

The high-altitude Andean Lakes (HAAL) areecosystems located in the South American Andes. These ecosystems are unique dueto their geographical characteristics, their broad range of extremeenvironments, as well their abundant biodiversity. Thegenus Exiguobacteriumis one of the most widespread and representative genera on the HAAL, beingdetected by direct (pure culture isolation) and indirect (DGGE) techniques. Thisgenera have been isolated or molecularly detected from a wide range of habitatsincluding cold and hot environments with temperature between-12 and 55°C. This fact confers substantial interest to the genus as apotential model system to research attributes that may correlate withadaptation and evolution of organisms to diverse thermalregimes. Exiguobacterium sp. S17 is a high arsenic resistantpolyextremophilic bacteria isolated from the stromatolites of L. Socompa. This strain is able to grow readily in laboratory and represents an attractive model system for the study of environmentalstress. Previous studies showed that Exiguobacterium sp. S17 is able to resistto high arsenic concentration and to produce biofilm. The aim of this work was toassess biofilms formation byExiguobacterium sp. S17 in different synthetic supports and to investigatethe influence of arsenic (As[III] y As[V]) in their development.Determination andquantification of biofilms was measured using crystal violet 1% following themethodology proposed by Tomaras et al., (2003). Biofilms production wasevaluated at different incubation times (24, 48 and 72 h) in LB50media (without As) and in different synthetic supports: sterile glass tubes (15x 125mm) and polypropylene (12 x 75 mm) and polystyrene plates (20 cm3).The influence of As was investigated supplemented LB50 with arsenate(As[V]): 50mM, 100 mM, 150 mM, 200mM, 250mM and arsenite (As[III]): 2.5 mM,5mM, 7.5 mM, 10 mM, 12.5 mM at the same time.ANOVA analyzes revealed that the optimal production of biofilms isachieved after 24 hours of growth and the highest biofilm production wasobtained when using glass as support and adding  arsenate (As [V]100 mM). No significant differences were observed when adding arsenite in comparison tocontrol medium (without arsenic).The findings obtained in this work made an important contribution to theknowledge of the biology and ecology of the microbial communities of the HAALin response to stress factors. Moreover, this method can be applied for thebenefit of human and environmental health by establishing an experimental basisfor a bioremediation method. Furthermore, we propose that HAAL is a source of novelbacterial species of biotechnological interest.Fil: Ordoñez, Omar Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Zannier, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Albarracín, Virginia Helena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaXI Congreso argentino de Microbiología GeneralCordobaArgentinaSociedad Argentina de Microbiología Genera