For 9 days, reaching 2,900 meters above sea level and only 100 meters away from the crater, a group of researchers explored and collected samples from the Copahue volcano and its surroundings, located in the BioBío Region of Chile and the Neuquén province of Argentina.

A multidisciplinary group of scientists, led by the researcher of Centro Basal Fundación Ciencia y Vida, Raquel Quatrini, explored the microbial ecosystem inhabiting the water bodies that emanate from the Copahue volcano, at limit between Chile and Argentina. The research is one of the first metagenomic studies carried out in the area that, among other things, will contribute knowledge on extremophile microorganisms that are of great interest for the mining industry in Chile and elsewhere.

The journey began on March 2, departing from Santiago towards Los Angeles, and then into the Andes Mountains. Surrounded by an intense smell of sulfur dioxide, the researchers carried out exhaustive work, collecting hundreds of samples from different parts of the system, traversing the environmental gradient that characterizes the area. But why is this system of scientific interest?

The area of Copahue or “place of sulfur” by its translation in Mapuche language, is characterized by a diverse landscape including high altitudes, rivers, waterfalls, lakes and lagoons. The region is known for its natural beauty and biodiversity, with endemic flora and fauna. On the slopes of the volcano, and accompanying the water course of the Agrio River, one can find forests of araucarias, ñires and lengas, as well as different species of animals such as lizards, condors, pumas and foxes.

For the research team, the place is an interesting study model due to its volcanic-glacial origin, and its particular characteristics. At the volcano heights, eternal ice, hot springs and fumaroles, ash and volcanic rocks encrusted with elemental sulfur are observed. The mixture of meltwater, with acidic hydro geothermal fluids which emanate from two springs at the base of the crater, gives rise to the Río Agrio. This water course enriched in sulfur and other chemical elements, provides the optimal conditions for the proliferation of several of the extremely acidophilic microorganisms, on which their study focuses.

In its nearly 40 kilometers of trajectory downhill, several freshwater tributaries dilute the Agrio River, generating habitats with different physicochemical characteristics that are the home of varied communities of microbial acidophiles. At the springs, communities resemble those of thermal environments; further downstream communities bear the signatures of those present in active mining sites, and others with characteristics of abandoned drainages.

“We have different types of communities in a single system, along a common longitudinal axis, which is the Agrio River, and which varies in its physicochemical characteristics. This is ideal for addressing community assembly studies,” explained Raquel Quatrini, PhD in Microbiology and expert in microbial genomics.

Acidophiles

Although most life occurs within normal pH, pressure, temperature and salinity ranges, there are microorganisms that have evolved adaptations that allow them to survive and thrive in environments with extreme characteristics, which are hostile or uninhabitable for most organisms. Examples of this are habitats with high pressure where only barophilic organisms proliferate; those with elevated temperatures where thermophiles are found, or habitats with extremely acidic pH where acidophiles prosper. All these microorganisms (extremophiles) deal with their extreme environments through a variety of biological and physiological mechanisms that border on science fiction.

Due to their capacity to endure extreme acidity and high concentrations of metals in solution, acidophiles are of great interest for the mining industry. Leaching is a process in which metals are extracted from rocks using chemical solutions. These are often highly acidic and toxic, harmful for both the environment and human health. In this context, mining biotechnologies offers a more ecological and safer alternative, increasing the recovery rates of metals of interest (such as copper) through the use of acidophilic microorganisms in bioleaching processes.

“For long, experts in biomining considered that a single microorganism (native or modified) could suffice to recover metals from a given mineral matrix. Today, instead, we consent that different sets of microorganisms, which we designate as ‘communities’ or ‘consortia’, are indeed responsible for mineral dissolution. These communities harbor the capacities to carry out the various reactions required to drive bioleaching under the changing conditions of active bioprocesses”, explained Dr. Quatrini. “How communities or the alternative states of these communities are configured to carry out these activities, or ecosystem functions, is not fully understood,” she added.

One of the objectives of the expedition was to collect concentrates from the native communities, which will be kept in bioreactors, and used in various community assembly tests to be carried out in the lab. “We will study how the communities are structured, modeling the metagenomic data collected from sites across the physicochemical gradient of the Río Agrio and the metadata recovered in this, and in previous sampling campaigns. In addition, we are going to carry out in vitro community assembly experiments, to test aspects of the models under controlled conditions”, commented the researcher Raquel Quatrini. 

“From the integration of these different study approaches, we expect to be able to understand how these communities are structured, what their composition is, how they change in space and time, that is, how communities assemble in alternative states over time as environmental factors gradually change across the rivers course”, she added.

Community outreach

The area surrounding the volcano generates great touristic interest. This is greatly due to the “Copahue Hot Springs”, located 18 km away from the town of Caviahue, famed  for  the curative and therapeutic properties of its waters. The thermal waters oscillate between 35° and 80° C (Celsius), and contain a wide variety of minerals such as iron, sulfur, calcium and magnesium, among others. 

Since 1870 they have been acknowledged for their ability to relieve muscle and joint pain, to improve blood circulation, reduce stress and anxiety, among other benefits. “They have a completely different approach to the hot springs that one knows in Chile, which are more recreational. At the Copahue Hot Springs, work is being done to treat pathologies using the different resources that come from the hot springs and other thermal manifestations, said the Universidad San Sebastian researcher and participant in the expedition, Simón Beard.

However, not all the waters that surround the Copahue Volcano have healthy and safe characteristics for humans, since there are significant concentrations of toxic ions, such as arsenic and fluoride.

“Part of this project seeks generating knowledge that is useful for the general public, making people aware of the peculiar characteristics of this system, so it may safeguarded and not excessively intervened. It is important that the unique characteristics of this system are recognized, so that it is not thought of as a system that should be remedied or repaired,” Beard said.

Considering several of its characteristics, the environments of this geothermal park recall the characteristics of the primitive world and provide unique windows to explore the evolutionary scenarios that have shaped life on our planet.

Collaborative work

The team led by Dr. Raquel Quatrini, from the Microbial Ecophysiology Laboratory of the Basal Center Fundación Ciencia & Vida, and associate professor at Universidad San Sebastian, explored the extreme system for 9 days in the company of collaborators.  Simón Beard, also researcher at USS and member of the team, evaluated the experience very positively. “There was a lot of mutual support among team members. Expeditions of this nature are very demanding physically and mentally, calling for high levels of diligence, tolerance and hard work, despite little sleep. Even if this is typical of field activities, hurdles’ are exacerbated in extreme environments, and this generate a very important strengthening of the work team”, he commented.

Away from the field, the project counts with the participation of different areas of knowledge, such as Computational Biology. Through a collaboration with doctor in biotechnology, Tomás Pérez-Acle, Director of the Basal Center Fundación Ciencia y Vida, said “data will be taken from the communities collected at different points along the Agrio River that runs downhill the Copahue volcano – almost as an introspection to the past, to the prehistoric past of the Earth – with the idea of understanding how these microbial communities work together almost as a kind of macroscopic living being”, explained Pérez-Acle.

“We will use mathematical algorithms and computational analyses to take the information of these multiple organisms that exist at each of the sampling points, and evaluate how this macroorganism changes as it moves along this gradient, because there is a temperature gradient, a chemical gradient, a physical gradient, which in some way makes life change”, he added.

The project financed by a FONDECYT project of the National Agency for Research and Development (ANID) is supported by international collaborators Dr. Alejandra Giaveno and Dr. Ricardo Ulloa, both from the University of Comahue, in the province of Neuquén in Argentina, and by Dr. Barrie Johnson, professor of Environmental Biotechnology at the University of Bangor in the United Kingdom, among others.

This project will contribute relevant information and knowledge on this type of extreme systems and the extremophilic communities that inhabit it, with eventual projections applied in biomining and environmental remediation. “All this study on the community structure, the assembly rules and the stability of acidophilic communities in the face of changes that occur in the environmental gradient, has direct application in the field of bioleaching, environmental protection and mitigation of damage from environmental contamination that can occur as a consequence of mining activity”, emphasized Dr. Quatrini.