This project aims to conduct a detailed investigation of the microbial diversity, metabolic potential and sulfur cycling bacteria within microbial mats developed in the Laguna Negra, a high-altitude Andean hypersaline lake in Catamarca, Argentina. Laguna Negra is considered to be an analogue for early Earth and, potentially, Mars sedimentary environments. Microbial activity plays a critical role in biogeochemical nutrient cycling and dissolution/precipitation of minerals and can leave biosignatures in the sedimentary record. Understanding the metabolic capabilities and sulfur bacteria communities in these microbial mats will allow us to relate them to carbonate precipitation processes and sulfur isotopes biosignatures there recorded.