Mapping Acidithiobacillus populations with high resolution onto a natural environmental gradient.

ISSOTA FRANCISCO; OLAVE IVET; ULLOA RICARDO; CHIACHARINI PATRICIA; GIAVENO ALEJANDRA; CUEVAS MAYRA; PEDROZO FERNANDO; DIAZ MÓNICA; TEMPORETTI PEDRO; JHONSON DANIEL; QUATRINI RAQUEL

Simposio; 18th International Symposium on Microbial Ecology; 2018

The Copahue-Caviahue-ChanchoCo geothermal system is a natural extreme environment located in the Andes mountain range of northern Patagonia. Two hydrothermal springs near the volcano crater are the source of an acidic watershed of unique characteristics in South America named Río Agrio. Along its journey from the source to Lake Caviahue, and downstream of the lake for an additional 40 Km, this 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 microorganisms. Several extreme acidophilic bacteria have been found to occur along this environmental gradient, including sulfur-oxidizing bacteria of the Acidithiobacillus species complex.In this study, the microdiversity of Acidithiobacillus populations inhabiting the Copahue-Caviahue-ChanchoCo geothermal system is analysed using culture-dependent and independent strategies. Genomic DNA extracted from representative isolates and environmental DNA obtained from diverse sampling points along the river, was used to PCR-amplify the 16S rRNA gene marker. After high throughput sequencing, phylogenetic and oligotyping analyses were 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 physic-geochemical gradient parameters 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.Acknowledgments: Universidad Andres Bello, Facultad de Ciencias Biologicas, Santiago, Chile (FI); CONICYT scholarship 21160871 (FI); PIP CONICET 0343 (PT); Fondecyt 1181251 (RQ); Basal AFB 170004 (RQ).