Hotspot for microbial life in the Puna de Atacama (Dry Andes): Effect of a fresh-water high-altitude temporary lake on the andesite microbial communities in the Barrancas Blancas Plain (Chile)

The Central Andes region, encompassing the Central Volcanic Zone and the Altiplano–Puna High Plateau, one of the most extreme mountain environments globally. Here we found the Barrancas Blancas Plain (68°39' W, 27°02' S, 5000 m.a.l.s), a unique ecological niche hosting a temporary lake. This area serves as a natural laboratory, facilitating the study of extremophiles and water's impact on microbial life in a desert environment. A 70-meter long moisture transect, from the lake to a dry reference site, uncovered a diverse microbial community using a novel intracellular DNA extraction method. Depth-related clustering was evident, with surface samples dominated by Proteobacteria and Bacteroides, while Gemmatimonadota increased with depth. As other Andean Lake environments, the prevalence of common primary producers such as Cyanobacteria was low in all samples. Gemmatimonadota exhibited higher abundance compared to similar environments, potentially playing a role in phototrophy and the nitrogen cycle. Additionally, surface samples at 8-23 meters away from the lake exhibited heightened ATP content and enzymatic activity, mirroring levels observed in forests and other water-favourable extreme environments. This heightened activity correlated with the prevalence of Proteobacteria and Bacteroidota. Despite being recognized as opportunistic microbes capable of degrading complex organic matter, studies in desert environments have revealed their adaptability in using alternative energy pathways, aligning with metabolic prediction analyses. In summary, this location emerges as a life hotspot amid the harsh mountain desert landscape, showcasing the significant influence of available water on microbial communities and their activities in the development of the ecosystem.