Characterization of Microbialites and Microbial Mats of the Laguna Negra Hypersaline Lake (Puna of Catamarca, Argentina)

Microbial carbonates provide an invaluable tool to understand biogeochemical processes in aqueous systems, especially in lacustrine and marine environments. Lakes are strongly sensitive to climatically driven environmental changes, and microbialites have recently been shown to provide a record of these changes. Unraveling physicochemical and microbiological controls on carbonates textures and geochemistry is necessary to correctly interpret these signals and the microbial biosphere record within sedimentary carbonates. The Laguna Negra is a high-altitude hypersaline Andean lake (Puna of Catamarca, Argentina), where abundant carbonate precipitation takes place and makes this system an interesting example that preserves a spectrum of carbonate fabrics reflecting complex physical, chemical, and biological interactions. The extreme environmental conditions (high UV radiation, elevated salinity, and temperature extremes) make the Laguna Negra a good analogue to some Precambrian microbialites (e.g., Tumbiana Fm., Archean, Australia). In addition, the discovery of ancient evaporating playa-lake systems on Mars’ surface (e.g., ShalbatanaVallis, Noachian, Mars) highlights the potential of Laguna Negra to provide insight into biosignature preservation in similar environments, in both terrestrial and extraterrestrial settings, given that microbial processes in the Laguna Negra can be studied with remarkable detail.Fil: Boidi, Flavia Jaquelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Mlewski, Estela Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Gomez, Fernando Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Centro de Investigaciones en Ciencias de la Tierra. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Centro de Investigaciones en Ciencias de la Tierra; ArgentinaFil: Gérard, Emmanuelle. Centre National de la Recherche Scientifique; Franci

The Discovery of Stromatolites Developing at 3570 m above Sea Level in a High-Altitude Volcanic Lake Socompa, Argentinean Andes

We describe stromatolites forming at an altitude of 3570 m at the shore of a volcanic lake Socompa, Argentinean Andes. The water at the site of stromatolites formation is alkaline, hypersaline, rich in inorganic nutrients, very rich in arsenic, and warm (20-24 degrees C) due to a hydrothermal input. The stromatolites do not lithify, but form broad, rounded and low-domed bioherms dominated by diatom frustules and aragonite micro-crystals agglutinated by extracellular substances. In comparison to other modern stromatolites, they harbour an atypical microbial community characterized by highly abundant representatives of Deinococcus-Thermus, Rhodobacteraceae, Desulfobacterales and Spirochaetes. Additionally, a high proportion of the sequences that could not be classified at phylum level showed less than 80% identity to the best hit in the NCBI database, suggesting the presence of novel distant lineages. The primary production in the stromatolites is generally high and likely dominated by Microcoleus sp. Through negative phototaxis, the location of these cyanobacteria in the stromatolites is controlled by UV light, which greatly influences their photosynthetic activity. Diatoms, dominated by Amphora sp., are abundant in the anoxic, sulfidic and essentially dark parts of the stromatolites. Although their origin in the stromatolites is unclear, they are possibly an important source of anaerobically degraded organic matter that induces in situ aragonite precipitation. To the best of our knowledge, this is so far the highest altitude with documented actively forming stromatolites. Their generally rich, diverse and to a large extent novel microbial community likely harbours valuable genetic and proteomic reserves, and thus deserves active protection. Furthermore, since the stromatolites flourish in an environment characterized by a multitude of extremes, including high exposure to UV radiation, they can be an excellent model system for studying microbial adaptations under conditions that, at least in part, resemble those during the early phase of life evolution on Earth

Diversity of arbuscular mycorrhizal fungi in soil from the Pampa Ondulada, Argentina, assessed by pyrosequencing and morphological techniques

Abstract: The aim of this study was to assess the effects of agronomic practices on the arbuscular mycorrhizal (AM) fungalcommunity in soils from the Pampa Ondulada region (Argentina), and to compare conclusions reached when using pyrosequencingor a morphological approach. The AM fungal diversity of 3 agricultural exploitations located in the Pampa Ondulada region(Argentina) was assessed by using 454 amplicon pyrosequencing and morphological (based on spore traits) approaches. Twokinds of soil managements are found in these sites: agronomic and non-agronomic. A total of 188 molecular operationaltaxonomic units and 29 morphological species of AM fungi were identified. No effect of soil management on AM richness wasdetected. AM fungal communities were more diverse and equitable in the absence of agronomic management. In contrast, theresults on -diversity varied according to the methodology used. We concluded that agronomic management of soil has anegative effect on AM fungal community biodiversity in the Pampa Ondulada region. We also conclude that both methodologiescomplement each other in the study of AM fungal ecology. This study greatly improved the knowledge about AM fungi in SouthAmerica where the molecular diversity of AM fungi was practically unknown

Diversity of arbuscular mycorrhizal fungi in soil from the Pampa Ondulada, Argentina, assesed by pyrosequencing and traditional techniques

The aim of this study was to assess the effects of agronomic practices on arbuscular mycorrhizal (AM) fungal community in soils from the Pampa Ondulada region (Argentina), and to compare conclusions reached when using pyrosequencing or morphological approach. AM fungal diversity was assessed in three agricultural exploitations located at the Pampa Ondulada region (Argentina) by 454 amplicon pyrosequencing and morphological (based on spore traits) approaches. Two kinds of soil managements are found in these sites (agronomic and non-agronomic). 188 Molecular Operational Taxonomic Units (MOTUs) and 29 morphological species of AM fungi were identified in total. Non effect of soil management on AM richness was detected. AM fungal communities were more diverse and equitable in absence of agronomic management. In contrast, results on beta diversity varied according to the methodology used. We concluded that agronomic management of soil has a negative effect on AM fungal community biodiversity in the Pampa Ondulada region. We also conclude that both methodologies complement each other in the study of AM fungal ecology. This study greatly improved the knowledge about AM fungi in South America where the molecular diversity of AM fungi was practically unknown.Fil: Colombo, Roxana. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Microbiología del Suelo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fernandez Bidondo, Laura. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Microbiología del Suelo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Silvani, Vanesa Analia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Microbiología del Suelo; ArgentinaFil: Carbonetto, María Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Agrobiotecnología de Rosario; ArgentinaFil: Rascovan, N.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Agrobiotecnología de Rosario; ArgentinaFil: Bompadre, Maria Josefina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pergola, Mariana. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Microbiología del Suelo; ArgentinaFil: Cuenca, G.. Instituto Venezolano de Investigaciones Científicas; VenezuelaFil: Godeas, Alicia Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Cs.exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Microbiología del Suelo; Argentin

A Unique Natural Laboratory to Study Polyextremophile Microorganisms: Diamante Lake as a Window to the Origin of Life

Diamante Lake is located at 4589 m above sea level (m a.s.l.) inside the Galán Volcano caldera and presents extreme environmental conditions, such as high arsenic concentration (210 mg l−1), salinity, pH and UV radiation. Until 2010, most studies in the area had largely overlooked the microbial biodiversity in Diamante Lake. With the advent of high throughput sequencing, it became possible to study the microbial communities of environmental samples using metagenomic approaches. In a recent work, we discovered red biofilms forming on the surface of sedimentary rocks on the bottom of the lake containing the rare mineral gaylussite. A metagenomic analysis of these biofilms revealed a predominance of haloarchaea (>96%) over other prokaryotic or eukaryotic organisms. To thrive under the extreme conditions in the lake, these biofilms use different metabolic and physiologic strategies: (1) to avoid the arsenic uptake into the cell, this is done through highly specific phosphate transporters (Pst) and consequently, (2) to take advantage bioenergetically of the high extracellular arsenic concentration and obtain energy from arsenite oxidation and to perform anaerobic respiration of arsenate. Contrary to what could be expected, the required enzymes for these arsenic metabolisms were likely not acquired recently by the selective pressure within Diamante Lake, but rather correspond to reminiscences of primitive metabolisms that could date back to even the origins of the haloarchaea lineage billions of years ago. Diamante Lake is a unique environment in the world and represents an open window to study the evolution of life on Earth and the adaptations required to survive under the extreme conditions that prevailed on the ancient Earth and that are currently found on other planets.Fil: Stepanenko, Tatiana Mariel. 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: Saona Acuña, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Lencina, Agustina Inés. 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