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Although arsenic (As) is recognized as a toxic element for living species, some microorganisms have the ability to tolerate and transform it; recent studies have proposed to take advantage of such capacity to develop sustainable bioremediation strategies. In this study, we evaluated the adaptation to increasing concentrations of As(III) and As(V) of three metabolically different microbial cultures (heterotrophic, autotrophic–acidophilic, and anaerobic) obtained from a sample with low‐soluble As content from the Copahue geothermal system. At the end of the adaptation process, the heterotrophic culture was able to grow at 20 mM and 450 mM of As(III) and As(V), respectively; the autotrophic– acidophilic culture showed tolerance to 15 mM of As(III) and 150 mM of As(V), whereas the anaerobic culture only developed in As(V) at concentrations up to 50 mM. The most tolerant consortia were characterized by their growth performance, complexity, and the presence of genes related to As metabolism and resistance. Regarding the consortia complexity, the predominant genera identified were: Paenibacillus in both heterotrophic consortia, Acidithiobacillus in the autotrophic–acidophilic consortium tolerant to As(III), Acidiphilium in the autotrophic–acidophilic consortium tolerant to As(V), and Thiomonas and Clostridium in the anaerobic consortium. This study is the first report of As tolerance microorganisms obtained from Copahue and reasserts the versatility and flexibility of the community of this natural extreme environment; also, it opens the door to the study of possible uses of these consortia in the design of biotechnological processes where the As concentration may fluctuate. Fil: Lima, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Urbieta, María Sofía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina Fil: Donati, Edgardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Fermentaciones Industriales. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Fermentaciones Industriales; Argentina

The millenary activity of extracting heavy metals (HM) is nowadays considered to be one of the main economic activities of the world with Mexico, Chile, China and Australia being some of the countries with higher productions. Due to their particular properties, HM were and still are, used in many industries and production activities. The impact of heavy metals in the diversity of microbial communities has been studied for several years. The methods used have evolved with the passage of time. Metals and metalloids can be classified into three categories according to their biological roles and effects on microorganisms Metatranscriptomics deals with the massive sequencing of the whole RNA of a microbial community and gives information on the genes that are expressed in certain conditions and time. Metagenomics, the massive sequencing of the microbial community DNA, can be applied to a specific gene, for example the 16S rRNA, or to the entire genetic material.

Assessing microbial communities in extreme environments allows the search for novel extremophilic microorganisms that can be of use in the development or improvement of biotechnological processes. Most microbial communities developed in such harsh environments have different heavy metal resistance strategies of importance in some technological applications as biomining but also in the bioremediation of metal-polluted environments. In this chapter we describe the microbial diversity of an acidic, volcanic geothermal environment in Northern Patagonia of Argentina: the Copahue geothermal system, containing different geothermal manifestations with temperatures up to 90 °C and pH values from 2 to 7 under aerobic and anaerobic conditions, provoking an enormous biodiversity. In addition, we report some heavy metal applications of those communities, focusing mainly in the bioprecipitation of heavy metals using sulfate-reducing microorganisms.