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

Integral Prospection of Andean Microbial Ecosystem Project

When microbial ecosystems first started to be reported 10 years ago, nobody reallyhad a notion of the relevance they would have in the Central Andean region.Consequently, the heritage of the microbialites reported in El Peinado, LagunaNegra, Laguna Pozo Bravo, Laguna La Brava, etc. promises to position the Andes asreservoirs of the most relevant modern microbialites on the planet (Table 17.1,Fig. 17.1). Furthermore, the number of different ecosystems is worth paying closeattention to, as it gives rise to questions such as: What favors the development ofthese ecosystems? What are the conditions that influence the precipitation of a carbonaceousor a gypsum system at such a short distance and under similar environmentalconditions, such as at the Atacama salt flat? Why are oncolites distributed so? Untilnow, it has been possible only to survey the systems and to carry out more in-depthstudies in some of them to try to achieve their preservation. Throughout the prospection of the Andean microbial ecosystems (AMEs), some shared characteristics have beenfound from the geological, physical, and chemical points of view [(1) active volcanicincidence: all of the microbial ecosystems that have been found are in some way connectedto areas where active volcanoes are present; (2) underground water input;(3) mixed zones with different salinities: underground low-conductivitywater andsalar thalassic water; (4) two kinds of microbialites found: oncolites (at LagunaNegra, Tres Quebradas, Las Quinoas, etc.) or domes with thrombolites at the bottomand stromatolites at the top surface (at La Brava, Pozo Bravo, Ojos Bravos, and ElPeinado)] and from the biological point of view [(5) predominance of diatoms, themain component in all studied systems; (6) predominance of anaerobic over aerobicphotosynthetic microorganisms; (7) microbial rhodopsin as the main system for producing adenosine triphosphate (ATP); (8) arsenicresistance and bioenergetic mechanisms;and (9) predominance of Carbon fixation pathways other than the Calvincycle]. The biological aspects of these are being studied thoroughly in our lab and arebriefly discussed below.Fil: Farias, Maria Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Villafañe, Patricio Guillermo. 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 de Investigaciones y Transferencia de Catamarca. Universidad Nacional de Catamarca. Centro de Investigaciones y Transferencia de Catamarca; Argentin

Complete Characterization of Stratified Ecosystems of the Salar de Llamara (Atacama Desert)

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).Here, we reviewed all the analysis carried out in these communities, involving taxonomic and functional studies by culture-independent techniques, analysis of the physicochemical parameters of the water and its relation with the microbial ecosystems, together with pigments, mineralogy, and the microscopic view.Regarding taxonomy, the major points analyzed were: (1) the taxonomic trends at phylum level showed that Proteobacteria and Bacteroidetes were the major components of these communities. (2) A low proportion of sequences associated with the phylum Cyanobacteria were detected in all the studied samples. (3) The increased proportion of sequences that could not be affiliated with any taxonomic group that is deposited in the databases. (4) The large amount of rare phyla represented by candidate phyla, such as OD1, OP1, OD8, Hyd24-12, and NKB19.The functional analysis, carried out in these gypsum evaporite systems, revealed that there was only a minor presence of oxygenic photosynthesizers in the community, and anoxygenic photosynthesis appears as an alternative for primary production. Since the Calvin?Benson cycle was scant, the low abundance of oxygenic photosynthesizers was also related to unusual carbon fixation pathways.Regarding physicochemical parameters of the water, the most interesting results were: (1) a huge amount of arsenic; (2) high salinity; (3) low nutrients and high levels of some ions, such as sodium, sulfate, and calcium. The low dissolved oxygen in most of the set points was low, which was consistent with the low proportion of oxygenic photosynthesizers in all the samples studied.Regarding the mineralogy, gypsum mainly compounded all the evaporitic domes, and the microbial mats present halite as the main mineral component.Fil: Rasuk, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Contreras Leiva, Manuel. Centro de Ecología Aplicada; ChileFil: Kurth, Daniel German. 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

Andean Microbial Ecosystems: Traces in Hypersaline Lakes About Life Origin

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.Fil: Saona Acuña, Luis Alberto. 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: Villafañe, Patricio Guillermo. 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: Stepanenko, Tatiana Mariel. 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

Arsenic and Its Biological Role: From Early Earth to Current Andean Microbial Ecosystems

Arsenic (As) is present in the Earth's crust and is widely distributed in the environment. It is frequently a component of sulfidic ores in the form of arsenides of nickel, cobalt, copper, and iron. The main sources of As are natural, mostly associated with volcanic areas and hydrothermal vents; further, it can also originate as a result of human activities: mining, waste treatment, and industrial activities, among others.Arsenic is a redox-active metalloid and exists in nature in four oxidation states: arsine [As(-III)], elemental [As(0)], arsenate [As(V)], and arsenite [As(III)]. These states vary according to changes in pH and the redox environment. The first two forms are relatively rare; naturally, As is found as As(V) or As(III). As(V) is predominant in oxygenated aqueous environments, while As(III) is found in reduced or anoxic conditions. Arsenic is a highly dangerous element, as As(III) is 100 times more toxic than As(V). Its greatest toxicity is due to the fact that it can bind to sulfhydryl groups, affecting the correct functioning of many enzymes and proteins. As(V), on the other hand, is a chemical analog of phosphate, so it can interact and eventually replace it in early steps in different ways. On our planet, there are environments with a high arsenic content.Our research group has worked in bioprospecting in Andean microbial ecosystems (AMEs) in the Atacama Desert, Bolivian Altiplano, and Argentine Puna (the so-called Puna?High Andes region). In all of these places, there are hypersaline lakes at altitudes higher than 3000 m above sea level (asl). These lakes share the common characteristic of high concentrations of arsenic, normally ranging between 12 and 230 mg L−1. This range of As concentrations is one of the highest ranges reported for hypersaline lakes.Fil: Saona Acuña, Luis Alberto. 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: Villafañe, Patricio Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Stepanenko, Tatiana Mariel. 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