Temporary lake sustains active heterotrophic microbial communities in poly-extreme high-altitude environments of the Atacama Desert

The Puna de Atacama, or Altiplano, is a high-altitude desert region known for its extreme environmental conditions, leading to limited biological activity and nutrient availability. This study explores the impact of a temporary lake on microbial communities in the Barrancas Blancas plain, a poorly studied area of this desert. A 70-meter moisture transect was established from the lake to a dry site, and a multidisciplinary approach was used, including physicochemical and enzymatic analyses, a novel DNA extraction method targeting intact microbial cells, and molecular techniques. Results showed that the temporary lake significantly increased microbial abundance and activity, comparable to non-desert environments. A peak in microbial activity was detected 8 to 23 meters from the lake, associated with the presence of Bacteroides and Proteobacteria, which likely degrade complex polymers from Artemia cysts and microbial mats. Despite oligotrophic conditions, the lake sustains a full food web, including bacteria, fungi, algae, and crustacean-like Artemia, possibly supported by cyanobacteria, anoxygenic phototrophs and trace gas oxidizers. This study highlights the crucial role of temporary lakes in supporting life in extreme environments like the Puna de Atacama.