A Deeper Look into the Biodiversity of the Extremely Acidic Copahue volcano-Río Agrio System in Neuquén, Argentina.

Germán Lopez Bedogni,Francisco L Massello,Edgardo Rubén Donati,Alejandra Giaveno,María Sofía Urbieta

doi:10.3390/microorganisms8010058

Abstract

The Copahue volcano-Río Agrio system, on Patagonia Argentina, comprises the naturally acidic river Río Agrio, that runs from a few meters down the Copahue volcano crater to more than 40 km maintaining low pH waters, and the acidic lagoon that sporadically forms on the crater of the volcano, which is studied for the first time in this work. We used next-generation sequencing of the 16S rRNA gene of the entire prokaryotic community to study the biodiversity of this poorly explored extreme environment. The correlation of the operational taxonomic units (OTUs)s presence with physicochemical variables showed that the system contains three distinct environments: the crater lagoon, the Upper Río Agrio, and the Salto del Agrio waterfall, a point located approximately 12 km down the origin of the river, after it emerges from the Caviahue lake. The prokaryotic community of the Copahue Volcano-Río Agrio system is mainly formed by acidic bacteria and archaea, such as Acidithiobacillus, Ferroplasma, and Leptospirillum, which have been isolated from similar environments around the world. These results support the idea of a ubiquitous acidic biodiversity; however, this highly interesting extreme environment also has apparently autochthonous species such as Sulfuriferula, Acidianus copahuensis, and strains of Acidibacillus and Alicyclobacillus.

Highlights

Acidic rivers are quite uncommon environments, their origins are majorly associated with volcanic activities
It receives the input of different snowmelt origin rivers and streams and it forms various waterfalls; in this study, this part of the Upper Rio Agrio (URA) is represented by sampling points AS1 and “Cascada de la Culebra” (CC) (Figure 1E)
The two geothermal sources of the river, VA1 and VA2, present pH values around 2, they differ in temperature (VA1 41.0 ◦C and VA2 28.8 ◦C), something already observed in previous samplings [27]

Summary

Introduction

Acidic rivers are quite uncommon environments, their origins are majorly associated with volcanic activities. Contrary to naturally acidic rivers, acidic environments originated by anthropogenic activity, such as mining, have been deeply studied. The interest in these systems relies on the threat that acid mine drainage represents for freshwater resources and water scarcity in general. Reports in this topic are 16S/18S rRNA gene diversity assessments, and characterizations and analyses of functions of interest such as iron and sulfur metabolism and heavy metal resistance mechanisms. Reports in this topic are 16S/18S rRNA gene diversity assessments, and characterizations and analyses of functions of interest such as iron and sulfur metabolism and heavy metal resistance mechanisms. [5,6,7,8,9]

Methods

Results

Conclusion