Microbial ecosystems in central Andes extreme environments: a window into early Earth microbial life

The central Andes mountains of South America contain numerous wetlands and salt flats. Due to the high altitude and volcanic activity of this region, these environments exhibit extreme conditions resembling those of ancient Earth, including low oxygen pressure, intense solar radiation, minimal precipitation, high evaporation rates, pronounced seasonal and daily temperature fluctuations, strong winds, and elevated arsenic concentrations. Therefore, the study of the microbial ecosystems inhabiting these unique environments is vital for reconstructing the geobiological processes that shaped ancient sedimentary deposits on Earth.

In my presentation, I report the discovery of biofilms, microbial mats, and microbialites in Salar de Antofalla, Salar Carachipampa, Volcán Galán, and Complejo de la Laguna Verde (Catamarca, Argentina) through a combination of satellite data and field prospection. By integrating physicochemical analyses, mineralogy (X-ray diffraction, XRD), bulk geochemistry, molecular and isotopic (stable carbon and hydrogen) analyses of lipid compounds, scanning micro X-ray fluorescence (µXRF), 16S and 18S ribosomal RNA amplicon sequencing, and metagenomic analyses, my research group has identified diverse microbial communities with metabolic capacities that induce mineralisation. Our findings suggest that carbon fixation and the metabolic drivers of alkalinity in microbialites evolved over time. Moreover, the variability in prokaryotic composition among microbialites demonstrates that carbonate precipitation is governed by metabolic potential rather than taxonomy, reinforcing their role as dynamic records of environmental conditions.