CONICET | Buscador de Institutos y Recursos Humanos

The Copahue-Caviahue-ChanchoCo geothermal system is a natural extreme environment located in the Andes mountain range of northern Patagonia, right at the border between Chile and Argentina. Two hydrothermal springs near the Copahue volcano crater are the source of the acidic Río Agrio, a watershed of unique characteristics in South America. Along its journey from the source to Lake Caviahue, and downstream of the lake for an additional 40 Km, the river features an ample gradient of pH (pH 0.5?8.5), temperature (10-80ºC) and conductivity (0.5-500 mS/cm). Several fumaroles, pools, ponds and hot springs away from the river path complete the system. The wide range of physical and chemical conditions measured in this environment support a great biodiversity of algae, archaea and bacteria. Several taxons of extreme acidophilic bacteria have been found to occur along this environmental gradient, including sulfur-oxidizers of the Acidithiobacillus species complex. In this study, the microdiversity of Acidithiobacillus populations inhabiting the Copahue-Caviahue-ChanchoCo geothermal system is explored using culture-dependent and independent strategies. Phylogenetic and oligotyping analysis of the 16S rRNA gene sequence is used to infer the taxonomy of the representative isolates and sequence clones and to resolve meaningful differences between closely related populations along the environmental gradient. The correlation between the emerging population structure and the physico(geo)chemical gradient is analysed through multivariate statistical analysis in order to gain insights into the ecological and evolutionary processes that structure and maintain microbial diversity in this ecosystem. Acknowledgements: Fondecyt 1140048, Basal CCTE PFB16 and CONICYT scholarships 21160871 and 21171049.