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As important parts of microbe–mineral associations, microalgae–montmorillonite composites are common in nature environment, which have been overlooked for a long time. In this study, the binding of Cd(II) in the montmorillonite, microalgae and their 1:5, 1:10 mass ratio composites interface were investigated. The results showed that maximum adsorption capacity of 1:5 and 1:10 mass ratio binary composites were 65.25 mg g−1 and 55.49 mg g−1, respectively, which both higher the theoretically calculated capacity from single montmorillonite and microalgae at pH 5.5. Fourier transform infrared spectrometer (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that phosphoryl and carboxyl functional groups on the algal cellular surface played major roles in both microalgae–montmorillonite composite formation and Cd(II) adsorption. Extended X-ray absorption fine structure (EXAFS) further probed that higher sorption on composites were attributed to Cd(II) bridging between microalgae and montmorillonite, in which monodentate phosphoryl-Cd and carboxyl-Cd complexes on microalgae side, leading Cd(II) to a more stabilized state. In addition, the montmorillonite promoted dispersion of microalgae, releasing more carboxyl and phosphoryl functional groups as Cd(II) binding sites on the microalgae surface. These findings highlight the function of microalgae in the microalgae–clay mineral associations for Cd(II) fixation and provide further insight into the sequestration and migration of toxic metals in natural environments.

Microbialite-producing microorganisms that inhabit the Puna lakes are traditionally considered constituents of fragile microsystems, unable to resist important environmental variations. Nevertheless, this region has experienced significant climatic fluctuations during the Holocene, raising the unsolved issue on how microbialite-forming systems have been able to resist these changes. Turquesa lake, located within Quaternary Peinado lake-basin (Puna), faces a hydric crisis in the last decades, which modified their physicochemical conditions. However, there has been a rapid re-establishment of the microbialite systems once the main parameters were stabilized, which allowed the establishment of three new microbialite levels in the coast and paleo-coastline. The aim of this contribution is to report for the first time microbialite levels in Turquesa lake, providing a multiscale analysis, besides an accurate study of the physico-chemical context of the lake. This new record provided us the opportunity to demonstrate the short-term resilience capacity of these microbialite-producing microorganisms to climatic changes, offering a key approach to understand analogue processes throughout Earth history.

The known diversity of the genus Liolaemus continues to increase, principally due to its great degree of endemism, the increasing number of researchers working on it, and advances in the taxonomic ...

Arsenic (As) is a metalloid present in the earth's crust and widely distributed in the environment. Due to its high concentrations in the Andean valleys and its chemical similarity with phosphorus (P), its biological role in Andean Microbial Ecosystems (AMEs) has begun to be studied. The AMEs are home to extremophilic microbial communities that form microbial mats, evaporites, and microbialites inhabiting Andean lakes, puquios, or salt flats. In this work, we characterize the biological role of As and the effect of phosphate in AMEs from the Laguna Tebenquiche (Atacama Desert, Chile). Using micro X-ray fluorescence, the distribution of As in microbial mat samples was mapped. Taxonomic and inferred functional profiles were obtained from enriched cultures of microbial mats incubated under As stress and different phosphate conditions. Additionally, representative microorganisms highly resistant to As and able to grow under low phosphate concentration were isolated and studied physiologically. Finally, the genomes of the isolated Salicola sp. and Halorubrum sp. were sequenced to analyze genes related to both phosphate metabolism and As resistance. The results revealed As as a key component of the microbial mat ecosystem: (i) As was distributed across all sections of the microbial mat and represented a significant weight percentage of the mat (0.17 %) in comparison with P (0.40%); (ii) Low phosphate concentration drastically changed the microbial community in microbial mat samples incubated under high salinity and high As concentrations; (iii) Archaea and Bacteria isolated from the microbial mat were highly resistant to arsenate (up to 500 mM), even under low phosphate concentration; (iv) The genomes of the two isolates were predicted to contain key genes in As metabolism (aioAB and arsC/acr3) and the genes predicted to encode the phosphate-specific transport operon (pstSCAB-phoU) are next to the arsC gene, suggesting a functional relationship between these two elements.

During evolution, microorganisms exposed to high amounts of UV-B irradiation developed fine-tuned photo-enzymes called ‘photolyases’ to cope with DNA damage caused by UV-B. These photoreceptors, belonging to the cryptochrome/photolyase family (CPF), have been 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 in 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 level in 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 found. Likewise, cryptochrome-like genes were found to be abundant in most exposed microbiomes, indicating a complementary role to standard photolyases. We observed that CPFs are more likely to be present in dominant taxa of the highly irradiated microbiomes, suggesting an evolutionary force for survival and dominance under extreme solar exposure. This work reports 3 novel CPF clades, proving the potential of global metagenomic analyses in detecting novel proteins.

Diamante Lake located at 4589 m.a.s.l. in the Andean Puna constitutes an extreme environment. It is exposed to multiple extreme conditions such as an unusually high concentration of arsenic (over 300 mg L−1) and low oxygen pressure. Microorganisms thriving in the lake display specific genotypes that facilitate survival, which include at least a multitude of plasmid-encoded resistance traits. Hence, the genetic information provided by the plasmids essentially contributes to understand adaptation to different stressors. Though plasmids from cultivable organisms have already been analyzed to the sequence level, the impact of the entire plasmid-borne genetic information on such microbial ecosystem is not known. This study aims at assessing the plasmidome from Diamante Lake, which facilitates the identification of potential hosts and prediction of gene functions as well as the ecological impact of mobile genetic elements. The deep-sequencing analysis revealed a large fraction of previously unknown DNA sequences of which the majority encoded putative proteins of unknown function. Remarkably, functions related to the oxidative stress response, DNA repair, as well as arsenic- and antibiotic resistances were annotated. Additionally, all necessary capacities related to plasmid replication, mobilization and maintenance were detected. Sequences characteristic for megaplasmids and other already known plasmid-associated genes were identified as well. The study highlights the potential of the deep-sequencing approach specifically targeting plasmid populations as it allows to evaluate the ecological impact of plasmids from (cultivable and non-cultivable) microorganisms, thereby contributing to the understanding of the distribution of resistance factors within an extremophilic microbial community. Fil: Perez, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Saona Acuña, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Poehlein, Anja. Universität Göttingen; Alemania Fil: Meinhardt, Friedhelm. Münster Universität; Alemania Fil: Daniel, Rolf. Universität Göttingen; Alemania Fil: Dib, Julian Rafael. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina

The Salar de Atacama in the Chilean Central Andes harbors unique microbial ecosystems due to extreme environmental conditions, such as high altitude, low oxygen pressure, high solar radiation, and high salinity. Combining X-ray diffraction analyses, scanning electron microscopy and molecular diversity studies, we have characterized twenty previously unexplored Andean microbial ecosystems in eight different lakes and wetlands from the middle-east and south-east regions of this salt flat. The mats and microbialites studied are mainly formed by calcium carbonate (aragonite and calcite) and halite, whereas the endoevaporites are composed predominantly of gypsum and halite. The carbonate-rich mats and microbialites are dominated by Bacteroidetes and Proteobacteria phyla. Within the phylum Proteobacteria, the most abundant classes are Alphaproteobacteria, Gammaproteobacteria and Deltaproteobacteria. While in the phylum Bacteroidetes, the most abundant classes are Bacteroidia and Rhodothermia. Cyanobacteria, Chloroflexi, Planctomycetes, and Verrucomicrobia phyla are also wellrepresented in the majority of these systems. Gypsum endoevaporites, on the contrary, are dominated by Proteobacteria, Bacteroidetes, and Euryarchaeota phyla. The Cyanobacteria phylum is also abundant in these systems, but it is less represented in comparison to mats and microbialites. Regarding the eukaryotic taxa, diatoms are key structural components in most of the microbial ecosystems studied. The genera of diatoms identified were Achnanthes, Fallacia, Halamphora, Mastogloia, Navicula, Nitzschia, and Surirella. Normally, in the mats and microbialites, diatoms form nano-globular carbonate aggregates with filamentous cyanobacteria and other prokaryotic cells, suggesting their participation in the mineral precipitation process. This work expands our knowledge of the microbial ecosystems inhabiting the extreme environments from the Central Andes region, which is important to ensure their protection and conservation., Centro de Investigaciones Geológicas

[EN] Extremophilic microorganisms were screened as biocontrol agents against two strains of Macrophomina phaseolina (Mp02 and 06). Stenotrophomonas sp. AG3 and Exiguobacterium sp. S58 exhibited a potential in vitro antifungal effect on Mp02 growth, corresponding to 52.2% and 40.7% inhibition, respectively. This effect was confirmed by scanning electron microscopy, where images revealed marked morphological alterations in fungus hyphae. The bacteria were found to secrete lytic enzymes and polyamines. Exiguobacterium sp. S56a was the only strain able to reduce the growth of the two strains of M. phaseolina through their supernatant. Antifungal supernatant activity was correlated with the ability of bacteria to synthesize and excrete putrescine, and the exogenous application of this polyamine to the medium phenocopied the bacterial antifungal effects. We propose that the combined secretion of putrescine, spermidine, and lytic enzymes by extremophilic microorganism predispose these microorganisms to reduce the disease severity occasioned by M. phaseolina in soybean seedlings., The authors acknowledge the generous financial support by the PICT V Bicentenario 2010 1788 Project (FONCyT, Argentina). This work was performed in the context of a project called ¿Análisis de Adaptación al Cambio Climático en Humedales Andinos¿. ID: 6188775¿8-LP13. Ministerio del Medio Ambiente, Región de Antofagasta. We are also grateful to Lic. C. Pérez Brandan for providing us with the M. phaseolina strains used in this study.

In this study, Chlorella sorokiniana FK, isolated from lead-zinc tailings, was employed for Pb(II) biomineralization with or without montmorillonite (MMT) addition in soil. Batch experiment results showed that montmorillonite facilitated Pb3(CO3)2(OH)2 formation on the surface of Chlorella-MMT composite, thus increasing algal cells' tolerance to Pb(II) poisoning. Surprisingly, Pb(II) adsorbed and biomineralized by Chlorella-MMT composite was 2.69 times and 3.76 times as much as that by Chlorella alone, respectively. The montmorillonite facilitated Chlorella-induced Pb biomineralization by promoting both photosynthesis and urea hydrolysis, mainly due to more hydroxyl functional groups generated during its binding with Chlorella and its high pH buffering capacity. Moreover, the SEM-EDS analysis indicated that the biomineral particles shifted from algal cell surface to montmorillonite surface in the composite during long-term Pb-detoxification. In-situ soil Pb(II) remediation experiments with Chlorella-MMT composites further showed that Pb was immobilized as carbonate form in the short term and as residue fraction in the long term. This study made the first attempt to explore the facilitating effects of montmorillonite on metal-carbonate precipitation mediated by microalgae and to develop a green, sustainable, and effective strategy for immobilization of heavy metal in soil by combining clay minerals and microalgae.

Central-Andean Ecosystems (between 2000 and 6000 m above sea level (masl) are typical arid-to-semiarid environments suffering from the highest total solar and ultraviolet-B radiation on the planet but displaying numerous salt flats and shallow lakes. Andean microbial ecosystems isolated from these environments are of exceptional biodiversity enduring multiple severe conditions. Furthermore, the polyextremophilic nature of the microbes in such ecosystems indicates the potential for biotechnological applications. Within this context, the study undertaken used genome mining, physiological and microscopical characterization to reveal the multiresistant profile of Nesterenkonia sp. Act20, an actinobacterium isolated from the soil surrounding Lake Socompa, Salta, Argentina (3570 masl). Ultravioet-B, desiccation, and copper assays revealed the strain’s exceptional resistance to all these conditions. Act20’s genome presented coding sequences involving resistance to antibiotics, low temperatures, ultraviolet radiation, arsenic, nutrient-limiting conditions, osmotic stress, low atmospheric-oxygen pressure, heavy-metal stress, and toxic fluoride and chlorite. Act20 can also synthesize proteins and natural products such as an insecticide, bacterial cellulose, ectoine, bacterial hemoglobin, and even antibiotics like colicin V and aurachin C. We also found numerous enzymes for animal- and vegetal-biomass degradation and applications in other industrial processes. The resilience of Act20 and its biotechnologic potential were thoroughly demonstrated in this work. Supplementary Information The online version contains supplementary material available at 10.1007/s11274-021-03129-9

The wetlands and salt flats of the Central Andes region are unique extreme environments as they are located in high-altitude saline deserts, largely influenced by volcanic activity. Environmental factors, such as ultraviolet (UV) radiation, arsenic content, high salinity, low dissolved oxygen content, extreme daily temperature fluctuation, and oligotrophic conditions, resemble the early Earth and potentially extraterrestrial conditions. The discovery of modern microbialites and microbial mats in the Central Andes during the past decade has increased the interest in this area as an early Earth analog. In this work, we review the current state of knowledge of Central Andes region environments found within lakes, small ponds or puquios, and salt flats of Argentina, Chile, and Bolivia, many of them harboring a diverse range of microbial communities that we have termed Andean Microbial Ecosystems (AMEs). We have integrated the data recovered from all the known AMEs and compared their biogeochemistry and microbial diversity to achieve a better understanding of them and, consequently, facilitate their protection., Centro de Investigaciones Geológicas

In this work, molecular diversity of two hypersaline microbial mats was compared by Whole Genome Shotgun (WGS) sequencing of environmental DNA from the mats. Brava and Tebenquiche are lakes in the Salar de Atacama, Chile, where microbial communities are growing in extreme conditions, including high salinity, high solar irradiance, and high levels of toxic metals and metaloids. Evaporation creates hypersaline conditions in these lakes and mineral precipitation is a characteristic geomicrobiological feature of these benthic ecosystems. The mat from Brava was more rich and diverse, with a higher number of different taxa and with species more evenly distributed. At the phylum level, Proteobacteria, Cyanobacteria, Chloroflexi, Bacteroidetes and Firmicutes were the most abundant, including ~75% of total sequences. At the genus level, the most abundant sequences were affilitated to anoxygenic phototropic and cyanobacterial genera. In Tebenquiche mats, Proteobacteria and Bacteroidetes covered ~70% of the sequences, and 13% of the sequences were affiliated to Salinibacter genus, thus addressing the lower diversity. Regardless of the differences at the taxonomic level, functionally the two mats were similar. Thus, similar roles could be fulfilled by different organisms. Carbon fixation through the Wood-Ljungdahl pathway was well represented in these datasets, and also in other mats from Andean lakes. In spite of presenting less taxonomic diversity, Tebenquiche mats showed increased abundance and variety of rhodopsin genes. Comparison with other metagenomes allowed identifying xantorhodopsins as hallmark genes not only from Brava and Tebenquiche mats, but also for other mats developing at high altitudes in similar environmental conditions. Fil: Kurth, Daniel German. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Elias, Dario Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones Médicas e Investigaciones Clínicas "Norberto Quirno". CEMIC-CONICET; Argentina Fil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Contreras, Emanuel. Centro de Ecología Aplicada (CEA); Chile Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina

Central Andean Ecosystems (between 2000 and 6000 masl) are typical arid to semiarid environments suffering from the highest total solar and UVB radiation on the planet but displaying numerous salt flats and shallow lakes. Isolated from these environments, Andean Microbial Communities (AME) of exceptional biodiversity endures multiple severe conditions. Also, the poly-extremophilic nature of AME’s microbes indicates the potential for biotechnological applications. In this context, the presented study used genome mining and physiological characterization to reveal the multi-resistant profile of Nesterenkonia sp. Act20, an actinobacterium isolated from the soil surrounding Lake Socompa, Salta, Argentina (3570 m). UV-B, desiccation, and copper assays showed the strain’s exceptional resistance to all these factors. Act20’s genome presented coding sequences involving antibiotics, low temperatures, UV and arsenic resistance, nutrient limiting conditions, osmotic stress response, low atmospheric oxygen pressure, heavy metal stress, and resistance to fluoride and chlorite. Act20 can also synthesize proteins and natural products such as an insecticide, bacterial cellulose, ectoine, bacterial hemoglobin, and even antibiotics like colicin V and aurachin C. We also found numerous enzymes for animal and vegetal biomass degradation and application in other industrial processes.The herein report shed light on the microbial adaptation to high-altitude environments, its possible extrapolation for studying other extreme environments of relevance, and its application to industrial and biotechnological processes.HIGHLIGHTSArid Andean Soils are attractive sources of microbial strains useful in biotechnological processes.Physiological studies revealed the multi-resistant nature of the poly-extremophile Nesterenkonia sp. Act20.Act20’s genome analysis showed a complete set of genes coding for proteins involved in resistance to multiple stresses, including extremoenzymes and extremolytes.

Laguna Tebenquiche is one of the largest waterbodies in the Salar de Atacama. The prokaryotic microorganisms inhabiting this lake are subjected to extreme conditions such as high solar radiation due to a lower barometric pressure at high altitude, extreme daily temperature fluctuations, severe changes in salinity caused by net evaporation, and high arsenic concentrations in the water owing to volcanic events. The microbial community of Laguna Tebenquiche was studied using culture-dependent and culture-independent molecular methods and more recently, metagenomic analyses. These multifarious approaches allowed determination of the prokaryotic diversity in the various microbial ecosystems comprising Laguna Tebenquiche. Here, we describe the main results from the different approaches/analyses, the most relevant results for understanding the ecology of this extreme environment, and discuss future perspectives for diversity/microbial ecological studies.

Peatlands are plant formations established in an edaphic environment, mainly organic, characterized by a water condition of permanent saturation, which works as an oasis that promotes abundant biological diversity in the arid high-altitude environment. Peatlands present cultural, environmental, and economic social relevance because they are sources of life and development for people who live in and depend on these ecosystems. These wetlands have begun to dry up, consequently leading to the loss of natural resources (flora and fauna) and damage to the ancestral rights to natural resources (including water) of indigenous communities, due to the acquisition and exploitation of water rights for non-agricultural uses (mainly mining) that are endangering the sustainability and survival of these groups. The relationship between microbial diversity and function in soil is largely unknown, but biodiversity is assumed to influence ecosystem stability, productivity, and resilience toward stress and disturbance. In this chapter, we will present the first performed approach of microbial diversity in peatland soils.

High-altitude Andean lakes (HAALs) represent unique environments on the Earth where one can study the biological chemistry of life in one of its most extreme versions. The Atacama Desert, Argentine Puna, and Bolivian Altiplano harbor hypersaline lakes where polyextremophilic Andean Microbial Ecosystems (AMEs) inhabit microbial mats, evaporitic mats, biofilms (BF), evaporites (EV), and microbialites (Mi). These AMEs have two remarkable characteristics: (i) they are the only ones in the world that inhabit areas ranging from 3100 to 4200 masl; and (ii) they are excellent modern analogues of those which populated the primitive Earth ~3 billion years ago. In this chapter, we will delve into the different kinds of AMEs present in the HAAL, their formation, structure, and their adaptation to conditions largely influenced by volcanic activity, UV radiation, arsenic content, high salinity, low dissolved oxygen content, extreme daily temperature fluctuation, and oligotrophic conditions. All of these physicochemical parameters recreate the early Earth and even extraterrestrial conditions. The relevance of studying these ecosystems does not lie only in scientific-descriptive and/or economic interest. The scientific research community has a great responsibility to address climate change. In this scenario, the AMEs could have played a key role, influencing changes that allowed the origin of aerobic life and those who have faced the great climatic events of the Earth.

Diamante Lake is located at 4589 m above sea level (m a.s.l.) inside the Galan 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.

While it is true that the chemistry of current life is well defined, 3.5 billion years ago, everything could have been different. Other elements may have been part of the chemical reactions that finally triggered an endless iteration with well-defined laws that gave way—and continue to give way—to the evolution of life. In this sense, arsenic could have been a key element for life back then. Its high reactivity and its abundance in the context of a reduced atmosphere could have given this element a key role, whereas nowadays it is so alien to the development of life. In this chapter, we address this question with a special emphasis on the description of one of the best natural laboratories to study early life that our planet presents: the Andean Puna.

Salar de Llamara is situated in the north of the Atacama Desert, which is the driest desert and one of the most irradiated places on Earth. Besides, its subterranean hypersaline waters contain a high content of arsenic, among other compounds such as heavy metals that are poisonous to life in the concentrations present. Despite these extreme conditions, diverse microbial communities flourish in gypsum stratified ecosystems (microbial mats and evaporitic domes).

The Salar de Atacama depression is a unique geomorphologic structure in northern Chile and is the oldest and largest evaporitic basin in that country. In the lowest region of the Atacama basin, groundwater surfaces forms a series of lakes that are exposed to the extreme conditions of the salar, including high ultraviolet radiation, low humidity, high water-column conductivity, and arsenic concentrations. Among these lakes, Laguna La Brava harbors a variety of living microbialites and microbial mats. Several studies have determined the microbial diversity and the genomic basis of the main metabolic pathways that allow these microbial ecosystems to thrive in such extreme conditions, which resemble Precambrian/Paleoproterozoic conditions. This chapter reviews the results published since these unusual ecosystems were first described 4 years ago.

Puna wetlands and salars are a unique extreme environment all over the world, since their locations are in high-altitude saline deserts, largely influenced by volcanic activity. Ultraviolet radiation, arsenic content, high salinity, and low dissolved oxygen content, together with extreme daily temperature fluctuations and oligotrophic conditions, shape an environment that recreates the early Earth and, even more so, extraterrestrial conditions. Microbes inhabiting extreme environments face these conditions with different strategies, including formation of intricate microbial communities with an increasing degree of complexity. In that way, biofilms, mats, endoevaporitic mats, domes, and microbialites have been found to exist in association with salars, lagoons, and even volcanic fumaroles in Central Andean extreme environments. They form microbial ecosystems, where light and O2 availability decrease with depth stratification, promoting functional group diversity. This microbial diversity, together with the geochemistry, may favor the precipitation of minerals. This chapter summarizes general concepts in the environmental microbiology of extreme Andean ecosystems, which are explored throughout this book.

Lithium (Li) is widely distributed in nature and has several industrial applications. The largest reserves of Li (over 85%) are in the so-called "triangle of lithium" that includes the Salar de Atacama in Chile, Salar de Uyuni in Bolivia and Salar del Hombre Muerto in Argentina. Recently, the use of microorganisms in metal recovery such as copper has increased; however, there is little information about the recovery of lithium. The strain Rhodococcus sp. A5wh used in this work was previously isolated from Laguna Azul. The assays revealed that this strain was able to accumulate Li (39.52% of Li/g microbial cells in 180 min) and that it was able to grow in its presence up to 1 M. In order to understand the mechanisms implicated in Li tolerance, a proteomic approach was conducted. Comparative proteomic analyses of strain A5wh exposed and unexposed to Li reveal that 17 spots were differentially expressed. The identification of proteins was performed by MALDI-TOF/MS, and the obtained results showed that proteins involved in stress response, transcription, translations, and metabolism were expressed under Li stress. This knowledge constitutes the first proteomic approach to elucidate the strategy followed by Rhodococcus to adapt to Li. El litio (Li) es un elemento químico con múltiples aplicaciones industriales. Es considerado uno de los minerales más ampliamente distribuidos en la naturaleza. Sus mayores reservas (más del 85%) se encuentran en el llamado «triángulo de litio»: salar de Atacama, en Chile; salar de Uyuni, en Bolivia, y salar del Hombre Muerto, en Argentina. En los últimos años, el empleo de microorganismos en la recuperación de metales se ha visto incrementado; sin embargo, hay muy poca información sobre la recuperación de Li por esta vía. En este estudio se trabajó con Rhodococcus sp. A5wh, cepa aislada de Laguna Azul. Los ensayos revelaron que este microorganismo fue capaz de acumular Li (39,52% de Li/g de biomasa en 180 min) y de crecer en presencia de este metaloide hasta una concentración de 1 M. Para comprender los mecanismos implicados en la tolerancia al Li, se llevó a cabo el análisis proteómico comparativo de esta cepa expuesta o no expuesta al Li. Los resultados revelaron 17 spots expresados en forma diferencial. La identificación de las proteínas se realizó porMALDI-TOF/MS. Este estudio constituye el primer enfoque proteómico para dilucidar la estrategia seguida por Rhodococcus en su adaptación al estrés.

The application of tandem MALDI-TOF MS screening with 16S rRNA gene sequencing of selected isolates has been demonstrated to be an excellent approach for retrieving novelty from large-scale culturing. The application of such methodologies in different hypersaline samples allowed the isolation of the culture-recalcitrant Salinibacter ruber second phylotype (EHB-2) for the first time, as well as a new species recently isolated from the Argentinian Altiplano hypersaline lakes. In this study, the genome sequences of the different species of the phylum Rhodothermaeota were compared and the genetic repertoire along the evolutionary gradient was analyzed together with each intraspecific variability. Altogether, the results indicated an open pan-genome for the family Salinibacteraceae, as well as the codification of relevant traits such as diverse rhodopsin genes, CRISPR-Cas systems and spacers, and one T6SS secretion system that could give ecological advantages to an EHB-2 isolate. For the new Salinibacter species, we propose the name Salinibacter altiplanensis sp. nov. (the designated type strain is AN15T = CECT 9105T = IBRC-M 11031T). Fil: Viver, Tomeu. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España Fil: Orellana, Luis. Instituto Tecnológico de Georgia; Estados Unidos. Georgia Institute of Techology; Estados Unidos Fil: González Torres, Pedro. Universidad de Alicante; España Fil: Díaz, Sara. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España Fil: Urdiain, Mercedes. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Benes, Vladimir. European Molecular Biology Laboratory Heidelberg; Fil: Kaempfer, Peter. Justus Liebig University Giessen; Fil: Shahinpei, Azadeh. University Of Tehran; Irán Fil: Ali Amoozegar, Mohammad. University Of Tehran; Irán Fil: Amann, Rudolf. Max Planck Institut Für Marine Mikrobiologie; Fil: Antón, Josefa. Universidad de Alicante; España Fil: Konstantinidis, Konstantinos T.. Georgia Institute of Techology; Estados Unidos. Instituto Tecnológico de Georgia; Estados Unidos Fil: Rosselló Móra, Ramon. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España

The hypersaline and extreme environments of the so-called high-altitude Andean lakes in the dry central region of the Andes are considered pristine ecosystems of biotechnological interest. By using culture-dependent and -independent methods, we aimed to describe the phylogenetic affiliation and ecological importance of Archaea thriving in extreme, hypersaline lakes and salt flats in the Argentinean and Chilean Puna. For this purpose, water and sediment samples were collected from 14 lakes and salt flats. Denaturing gradient gel electrophoresis (DGGE) indicated that representatives of the phylum Euryarchaeota dominated the microbial community in all samples. Most of the DGGE bands were assigned to the family Halobacteriaceae, while the rest corresponded to Methanocaldococcaceae, Methanobacteriaceae, Methanococcaceae, Methanosarcinaceae, and Methanothermaceae. In addition, isolation procedures yielded single colonies of 53 pure isolates belonging to the following genera: Haloarcula, Halomicrobium, Halopiger, Halorubrum, Natrialba, Natrinema, Natronorubrum, and Natronococcus. All strains proved to be polyextremophiles, with high tolerance to NaCl, UV-B radiation, and high arsenic concentration. Fil: Maldonado, Marcos Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Albarracín, Virginia Helena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Lara, José Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Ferrero, Marcela Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina

Microorganisms are globally distributed but new evidence shows that the microbial structure of their communities can vary due to geographical location and environmental parameters. In this study, 50 samples including brines and sediments from Europe, Spanish-Atlantic and South America were analysed by applying the operational phylogenetic unit (OPU) approach in order to understand whether microbial community structures in hypersaline environments exhibited biogeographical patterns. The fine-tuned identification of approximately 1000 OPUs (almost equivalent to ?species?) using multivariate analysis revealed regionally distinct taxa compositions. This segregation was more diffuse at the genus level and pointed to a phylogenetic and metabolic redundancy at the higher taxa level, where their different species acquired distinct advantages related to the regional physicochemical idiosyncrasies. The presence of previously undescribed groups was also shown in these environments, such as Parcubacteria, or members of Nanohaloarchaeota in anaerobic hypersaline sediments. Finally, an important OPU overlap was observed between anoxic sediments and their overlaying brines, indicating versatile metabolism for the pelagic organisms. Fil: Mora Ruiz, M.del R.. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España Fil: Cifuentes, Ana. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España Fil: Font Verdera, Francisca. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España Fil: Pérez Fernández, César A.. Universidad de Puerto Rico; Puerto Rico Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: González, Bernardo V.. Universidad Adolfo Ibanez; Chile Fil: Orfila, Alejandro. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España Fil: Rosselló Móra, Ramón. Consejo Superior de Investigaciones Cientificas. Instituto Mediterraneo de Estudios Avanzados; España

The aim of this study was to understand the spatial distribution of microbial communities (18S and 16S rRNA genes) across one of the harshest terrestrial landscapes on Earth. We carried out Illumina sequencing using samples from two expeditions to the high slopes (up to 6050 m.a.s.l.) of Volcán Socompa and Llullaillaco to describe the microbial communities associated with the extremely dry tephra compared to areas that receive water from fumaroles and ice fields made up of nieves penitentes. There were strong spatial patterns relative to these landscape features with the most diverse (alpha diversity) communities being associated with fumaroles. Penitentes did not significantly increase alpha diversity compared to dry tephra at the same elevation (5825 m.a.s.l.) on Volcán Socompa, but the structure of the 18S community (beta diversity) was significantly affected by the presence of penitentes on both Socompa and Llullaillaco. In addition, the 18S community was significantly different in tephra wetted by penitentes versus dry tephra sites across many elevations on Llullaillaco. Traditional phototrophs (algae and cyanobacteria) were abundant in wetter tephra associated with fumaroles, and algae (but not cyanobacteria) were common in tephra associated with penitentes. Dry tephra had neither algae nor cyanobacteria but did host potential phototrophs in the Rhodospirillales on Volcán Llullaillaco, but not on Socompa. These results provide new insights into the distribution of microbes across one of the most extreme terrestrial environments on Earth and provide the first ever glimpse of life associated with nieves penitentes, spire-shaped ice structures that are widespread across the mostly unexplored high-elevation Andean Central Volcanic Zone.

Cerro Tocorpuri, belongs to the II region of Chile, in San Pedro de Atacama, on the border of Chile-Bolivia. The presence of a more or less constant supply of water conditions the existence of characteristic vegetation systems known as bogs (bofedales, vegas and marshes). These wetlands have a cultural, environmental and economic social importance. As a result of the exploitation of aquatic rights peatlands began to dry up with the consequent loss of natural resources and damage to ancestral rights, and natural resources. The microbiome in wetlands plays an important role in biogeochemical processes and microbial activities there is crucial to the functions of wetland systems. The relationship between microbial diversity and soil function is unknown, but it has been assumed that biodiversity influences ecosystem stability, productivity, and resilience to stress. In the present work, the soil characteristics and the associated microbial biodiversity were studied, comparing samples of active and deteriorated peatland. It was seen that the loss of water causes great changes in the physical-chemical characteristics of the soil, which leads to a modification of the microbiota Proteobacteria decreased by 18% in deteriorated peatlands, which are evident more sensible to extreme conditions while Acidobacteria, Actinobacteria increased in these sample showing a better adaptation to the change of conditions. In view of the fact, that high Andean Peatlands are exposed to increasing environmental impact. This preliminary comparative study of pristine and altered soil could guide the research directed to recovery of dead peatlands strategies. Fil: Belfiore, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Fernandez, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Santos, Ana Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Contreras, Manuel. Pontificia Universidad Católica de Chile. Facultad de Ciencias Biológicas. Departamento de Ecología; Chile Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina

The combined electrosorption and chemisorption (CEC) behavior of As(III) with diluted concentration by manganese dioxide (MnO2) as the electrode was studied in this work. The CEC adsorption was better conformed to the pseudo-first-order kinetics and Langmuir model with the maximum adsorption capacity of 10.45 mg/g. Moreover, the conversion rate of As(III) to As(III) can reach 98% at pH 4 and 1 V with an initial As(III) concentration of 3.5 mg/L, which was almost 2.2 times of that with only chemisorption. The conversion of As(III) to As(V) can be attributed to the oxidation by MnO2 on the electrode and further enhanced by the electrostatic force provided by applied voltage.

Phosphate and arsenate are very similar compounds, and there is great interest in studying their relationship and their interaction with biological systems. Despite having no apparent biological function, specific genes regulate arsenic interaction with cells and can be located in regions of the genome called arsenic islands, where phosphate metabolism genes are also present. Although they are neighboring genes, the nature of their relationship and how they have been selected is still unknown.In this work, we analyzed the metagenomes of the four microbial ecosystems inhabiting hypersaline lakes of the Argentine Puna and the Atacama salt flat in Chile and have evaluated the presence and abundance of both arsenic and phosphate metabolism genes. The samples analyzed included microbialites, biofilms and microbial mats; all of them established under high arsenic concentrations, high UV radiation and high temperature fluctuation, among others.The results show great differences in the dispersion and abundance of genes related to both phosphate and arsenic metabolism in the analyzed samples. The main difference is given in the Diamante Lake, located in the crater of the Galan volcano characterized by being one of the lakes with the highest arsenic concentration (2.34 mM). Correlating genes abundance with the physicochemical parameters of the lakes studied, our results suggest that arsenic and phosphate metabolism are intricately co-regulated in environmental conditions.

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; Argentina Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Albarracín, Virginia Helena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina

The recently discovered "living" stromatolites in the Argentinean Puna are considered one of the most extreme stromatolites found so far. A rich biodiversity of bacteria, archaea and algae were previously reported in such stromatolites. As nematodes are the most numerous multicellular animals on Earth, the aim of this work was to investigate their presence in the stromatolites from Socompa lake at 3570 meters above sea level (masl). Nematodes were extracted and identified as belonging to the Monhysteridae family, with 91-92% homology to Diplolaimella dievengatensis. The phylogenetic analysis suggested they are novel species and probably belong to a new genus. This study represents the first report related to the presence of novel nematodes in such peculiar stromatolites. Knowing their functions and genetic features involved in the adaptation to these harsh conditions could help to elucidate important aspects about the ecological impact of these organisms in hostile environments. Недавно обнаруженные живые строматолиты Андского плоскогорья считаются самыми необычными из всех известных ранее. Богатство разнообразия бактерий и архей было ранее отмечено для строматолитов. Поскольку нематоды — самые многочисленные многоклеточные на планете Земля, то задачей работы было обнаружение нематод в строматолитах озера Сокомпа, расположенного на 3570 метров над уровнем моря. В ходе работы нематоды были обнаружены и определены как принадлежащие семейству Monhysteridae и с вероятностью 91–92% отнесены к виду Diplolaimella dievengatensis. В то же время филогенетический анализ показал, что обнаруженный вид представляет собой новый для науки вид, принадлежащий неописанному ранее роду нематод. Настоящая работа представляет собой краткое информационное сообщение о первой находке нематод в необычных пресноводных строматолитах. Новые знания о функциональных и генетических особенностях, приведших к адаптации в необычных условиях среды, позволят понять экологическую роль нематод в сообществах пресноводных строматолитов. Fil: D'almeida, Romina Elisa. 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 Fil: García, Marcia Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Perez, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Dib, Julian Rafael. 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; Argentina

High levels of arsenic present in the High Altitude Andean Lakes (HAALs) ecosystems selected arsenic-resistant microbial communities which are of novel interest to study adaptations mechanisms potentially useful in bioremediation processes. We herein performed a detailed characterization of the arsenic tolerance profiles and the biofilm production of two HAAL polyextremophiles, Acinetobacter sp. Ver3 (Ver3) and Exiguobacterium sp. S17 (S17). Cellular adherence over glass and polypropylene surfaces were evaluated together with the effect of increasing doses and oxidative states of arsenic over the quality and quantity of their biofilm production. The arsenic tolerance outcomes showed that HAAL strains could tolerate higher arsenic concentrations than phylogenetic related strains belonging to the German collection of microorganisms and cell cultures (Deutsche Sammlung von Mikroorganismen und Zellkulturen, DSMZ), which suggest adaptations of HAAL strains to their original environment. On the other hand, the crystal violet method (CV) and SEM analysis showed that Ver3 and S17 were able to attach to solid surfaces and to form the biofilm. The quantification of biofilms production in 48 hours´ cultures through CV shows that Ver3 yielded higher production in the treatment without arsenic cultured on a glass support, while S17 yield higher biofilm production under intermediate arsenic concentration on glass supports. Polypropylene supports had negative effects on the biofilm production of Ver3 and S17. SEM analysis shows that the highest biofilm yields could be associated with a larger number of attached cells as well as the development of more complex 3D multicellular structures. Fil: Zannier, Federico. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Portero, Luciano Raúl. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Tucumán; Argentina Fil: Ordoñez, Omar Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Martinez, Luciano Jose. Universidad Nacional de Tucumán; Argentina Fil: Farias, Maria Eugenia. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Albarracín, Virginia Helena. Universidad Nacional de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina

The Salar de Antofalla (salt flat) is located in the Puna region of Catamarca, in northern Argentina. In this paper we report and provide the first descriptive data of Las Quínoas, a modern system of oncoids located in the western margin of the salt flat. Oncoids were studied by insitu logging, polished and thin sections analysis. In addition, the 16s rRNA genes of microbial mats associated with these oncoids were amplified and sequenced to characterize the microbial biodiversity. Oncoids present discoidal to subrounded morphologies and sizes up to 15 cm in diameter. They are scattered along channels, which originate from the groundwater springs of a wetland and enter the salt flat. Its macrostructure is concentric and composed by three zones: 1. A nucleus zone built by clastic material in a carbonate matrix. 2. A well-laminated zone around the nucleus that shows two types of mesostructures: concentrically stacked spheroids (SS-C) and randomly stacked hemispheroids (SS-R), both showing an alternation of dense and dark micritic laminae with light micritic to microsparitic laminae. 3. A poorly-laminated zone, in the outermost sector of oncoids, with two types of mesostructures too: a laminated mesostructure composed also of an alternation of dense and dark micritic laminae with light micritic to microsparitic laminae, and a non-laminated mesostructure composed of agglomerated and cemented clastic material within a calcareous matrix (wackestones-packstones). Regarding the microbial diversity, the analyzed oncoids in this work are mainly inhabited by Proteobacteria (ca. 37.5%), Bacteroidetes (ca. 25.0%), and in less proportion Planctomycetes, Actinobacteria and Cyanobacteria. El salar de Antofalla se encuentra en la región de la Puna de Catamarca, en el norte de Argentina. En este artículo informamos y proporcionamos los primeros datos descriptivos de Las Quínoas, un sistema moderno de oncoides ubicado en el margen occidental de este salar. Ellos se estudiaron mediante registro in situ, análisis de secciones pulidas y delgadas. Además, los genes de ARNr 16s de tapices microbianos asociados con estos oncoides se amplificaron y secuenciaron para caracterizar la biodiversidad microbiana. Los oncoides presentan morfologías discoidales a subredondeadas y tamaños de hasta 15 cm de diámetro. Se encuentran dispersos a lo largo de canales, que se originan de las surgentes de agua de una vega y entran al salar. Su macroestructura es concéntrica y está compuesta por tres zonas: 1. Una zona de núcleo construida por material clástico en una matriz de carbonato. 2. Una zona bien laminada alrededor del núcleo que muestra dos tipos de mesoestructuras: esferoides concéntricamente apilados (SS-C) y hemisferoides apilados aleatoriamente (SS-R), ambos con una alternancia de láminas micríticas densas y oscuras con micríticas claras a microesparíticas. 3. Una zona pobremente laminada, en el sector más externo de los oncoides, también con dos tipos de mesoestructuras: una mesoestructura laminada compuesta por la alternancia de láminas micríticas densas y oscuras con láminas micríticas claras a microesparíticas, y una mesoestructura no laminada compuesta de material clástico aglomerado y cementado dentro de una matriz calcárea (wackestones-packstones). En cuanto a la diversidad microbiana, los oncoides analizados en este trabajo están habitados principalmente por Proteobacterias (ca. 37,5%), Bacteroidetes (ca. 25,0%), y en menor proporción Planctomicetes, Actinobacterias y Cianobacterias. Fil: Villafañe, Patricio Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Saona Acuña, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Gómez, Fernando Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: 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; Argentina Fil: Soria, Mariana Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina

In this study, living algae Didymogenes palatina XR was cultured in high-phosphorus medium for efficient Cd2+ immobilization from diluted wastewater solution. Algae cultivated from different phosphorus concentration medium was used to investigate its production and adsorption performances of Cd2+. This study showed that microalgae is sensitive to low concentration of heavy metal Cd, and different concentrations of phosphorus culture could regulate the surface phosphorus loading of microalgae to enhance its adsorption ability of Cd2+. The Cd2+ was further immobilized with the algae surface phosphorus group, such as PO43−, HPO4−, forming metallic mineral Cd-phosphate.

Arsenic is best known as an environmental toxin, but this element could also serve as a metabolic energy source to certain microorganisms. Moreover, As cycling may have driven microbial life on early Earth prior to oxygenation of the atmosphere. Still, little is known about the arsenic cycling processes occurring in the presence of microorganisms and the possible traces that could be preserved in the rock record. To advance our understanding of this we studied the geochemical proxies of microbial As metabolism in living microbialites from Laguna Diamante, a likely Precambrian ecosystem analogue (Catamarca, Argentina). In this study, we show that the coexistence of As(III) and As(V) strongly supports the presence of active microbially arsenic cycling in these microbialites. In addition, we propose a model by which arsenic metabolic processes can be preserved and interpreted as biosignatures in modern systems as well as in the rock record. Fil: Sancho Tomas, María. Institut de Physique Du Globe de Paris; Francia Fil: Somogyi, Andrea. Synchrotron Soleil; Francia Fil: Medjoub, Kadda. Synchrotron Soleil; Francia Fil: Bergamaschi, Antoine. Synchrotron Soleil; Francia Fil: Visscher, Pieter T.. Université de Bourgogne Franche-Comté; Francia. Centre National de la Recherche Scientifique; Francia Fil: van Driessche, Alexander E. S.. Universite Grenoble Alpes.; Francia. Centre National de la Recherche Scientifique; Francia Fil: Gérard, Emmanuelle. Institut de Physique Du Globe de Paris; Francia. Centre National de la Recherche Scientifique; Francia Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Contreras, Manuel. Centro Ecologia Aplicada; Chile Fil: Philippot, Pascal. Université de Montpellier; Francia. Centre National de la Recherche Scientifique; Francia

Biofilms, microbial mats, and microbialites dwell under highly limiting conditions (high salinity, extreme aridity, pH, and elevated arsenic concentration) in the Andean Puna. Only recent pioneering studies have described the microbial diversity of different Altiplano lakes and revealed their unexpectedly diverse microbial communities. Arsenic metabolism is proposed to be an ancient mechanism to obtain energy by microorganisms. Members of Bacteria and Archaea are able to exploit arsenic as a bioenergetic substrate in either anaerobic arsenate respiration or chemolithotrophic growth on arsenite. Only six aioAB sequences coding for arsenite oxidase and three arrA sequences coding for arsenate reductase from haloarchaea were previously deposited in the NCBI database. However, no experimental data on their expression and function has been reported. Recently, our working group revealed the prevalence of haloarchaea in a red biofilm from Diamante Lake and microbial mat from Tebenquiche Lake using a metagenomics approach. Also, a surprisingly high abundance of genes used for anaerobic arsenate respiration (arr) and arsenite oxidation (aio) was detected in the Diamante’s metagenome. In order to study in depth the role of arsenic in these haloarchaeal communities, in this work, we obtained 18 haloarchaea belonging to the Halorubrum genus, tolerant to arsenic. Furthermore, the identification and expression analysis of genes involved in obtaining energy from arsenic compounds (aio and arr) showed that aio and arr partial genes were detected in 11 isolates, and their expression was verified in two selected strains. Better growth of two isolates was obtained in presence of arsenic compared to control. Moreover, one of the isolates was able to oxidize As[III]. The confirmation of the oxidation of arsenic and the transcriptional expression of these genes by RT-PCR strongly support the hypothesis that the arsenic can be used in bioenergetics processes by the microorganisms flourishing in these environments. Fil: Ordoñez, Omar Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Soria, Mariana Noelia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Contreras, Manuel. Centro de Ecología Aplicada; Chile Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina

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; Argentina Fil: Santos, Ana Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina

Understanding how microorganisms adapted to the high arsenic concentration present on early Earth requires understanding of the processes involved in the arsenic biogeochemical cycle operating in living microbial mats. To this end, we investigated a living microbial mat from Laguna Brava (Salar de Atacama, Chile), a hypersaline lake with high arsenic concentration, using an array of conventional geochemical techniques, such as X-ray diffraction, SEM-EDX and Confocal Laser Scanning Microscopy (CLSM), combined with state-of-the-art high resolution scanning imaging techniques, including X-ray micro-fluorescence (μXRF) and X-ray Absorption Near Edge Structure (XANES) mapping. This experimental approach allowed us to unravel the relationship between the microbial mat activity, mineral occurrence, arsenic speciation, distribution of major and trace elements and their relationship with the mineralogy and the exopolymeric substances (EPS). We show that As was not linked to Ca or Si, and only moderately related to Fe, resulting from sorption onto an iron (oxy)hydroxide mineral. In addition, we were able to identify organic-rich globules containing significant As but no other trace metal(loid)s, and determine the co-existence of As(III) and As(V). These observations strongly support the occurrence of microbially-mediated arsenic cycling in these microbial mats. Fil: Sancho Tomás, María. Institut de Physique Du Globe de Paris; Fil: Somogyi, Andréa. Soleil Synchrotron; Fil: Medjoubi, Kadda. Soleil Synchrotron; Fil: Bergamaschi, Antoine. Soleil Synchrotron; Fil: Visscher, Pieter T.. University of Connecticut; Estados Unidos. Université Bourgogne Franche-comté; Fil: Van Driessche, Alexander E.S.. Institut Des Sciences de la Terre, Grenoble; Fil: Gérard, Emmanuelle. Institut de Physique Du Globe de Paris; Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina Fil: Contreras, Manuel. Centro Ecologia Aplicada; Chile Fil: Philippot, Pascal. Institut de Physique Du Globe de Paris

Carbonate microbialites provide a window to understand microbe-mineral interactions in modern environments and in the geological record. Unraveling microbial versus physicochemical controls and biogeochemical signatures is not always straightforward. Environmental and laboratory studies have shown that microbial activity can play a central role in calcium carbonate precipitation. Most studies have focused on the effects of Bacteria and Archaea activity on carbonate precipitation processes (e.g., cyanobacteria, sulfate-reducing bacteria, sulfide-oxidizing bacteria and iron-reducing bacteria). The influence of eukaryotic activity, such as diatoms and other microalgae, on carbonate precipitation and microbialite formation has been the focus of less attention. This study explores carbonate mineralization in active diatom-rich microbial mats developed in a high-Altitude groundwater-fed hypersaline lake in the Puna region of Catamarca, Argentina. Previous work has focused on the texture, mineralogy, and stable-isotope chemistry of the subfossil oncoidal and laminar microbialites. Here, using 16S rDNA Bacteria diversity analysis, confocal scanning laser microscopy, scanning electron microscopy, and transmittedlight microscopy, we explore the Bacteria and diatom diversity in the microbial mats and the related carbonates textures and make comparisons with similar textures in the associated oncoidal microbialites. Diatom-rich subspherical aggregates, which have not been previously described in the literature, show a diverse microbial community with abundant exopolymeric substances (EPSs) where carbonate precipitation takes place. These aggregates are a main component of the Laguna Negra microbial mats and show anhedral micritic calcite in the EPS matrix as the main mineral component. Similar calcite micrite textures are also preserved as one lamina type in the associated oncoids. On the other hand, where EPS are absent, carbonate precipitation, related to pennate diatom blooms, is represented by euhedral aragonite needles suggesting different mechanisms and controls. Changes in the microbial communities are recorded in the oncoids as different lamina types, providing a link between the currently active mats and the subfossil oncoidal structures. This is a first survey of these previously unexplored diatom-rich microbial mats developed under extreme environmental conditions in the Laguna Negra. Understanding the effect that the interaction between diatoms and prokaryotic communities has on carbonate precipitation may provide some insight on the evolution of microbialite textures and fabrics, and on the change from prokaryote-dominated systems to mixed eukaryotic-prokaryotic systems. Fil: 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; Argentina Fil: Mlewski, Estela Cecilia. Universidad Nacional de Córdoba; Argentina. 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; Argentina Fil: Boidi, Flavia Jaquelina. Universidad Nacional de Córdoba; Argentina. 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; Argentina Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentina. Universidad Nacional de Córdoba; Argentina Fil: Gérard, Emmanuelle. Université Paris Diderot - Paris 7; Francia