第七届青年地学论坛

The search for signs of life on Mars has been the ultimate goal of the existing Mars exploration missions and pivotal to understanding the planetary evolution and life sustainbility. The current climate of Mars is characterized by extreme aridity and freezing temperatures, while there are widespread deposits of chloride, sulfate and perchlorate minerals, and desiccating saline lakes. However, life has been widely reported to persist under high salinity and low moisture in hypersaline environments on earth, which may hold the key to the search for life on Mars. The Barkol Lake (43.61ºN 92.82ºE), situated to the northeast of the Tianshan Mountains, Xinjiang, is a hypersaline lake featured with cold (the lowest recorded temperature of -43.2°Celsius) and dry (potential evaporation far exceeding precipitation) climate as well as abundant mirabilite (Na₂SO₄•10H₂O) and halite (NaCl) minerals. Due to its cold and dry climate and salt environment, the Barkol Lake can be a potential analog for ancient saline paleolakes on Mars. Therefore, to understand the Barkol Lake system, we sampled the lake water and sediments (across the depth profile and horizontal transect) from the Barkol lake in order to understand the microbial community structure and diversity in hypersaline lake systems. Results showed that: (1) the Barkol Lake is dominated by bacterial community Proteobacteria, Firmicutes and Bacteroidetes as well as archaea community Parvarchaeota, Euryarchaeota and Crenarchaeota; (2) microbial community structure differed significantly between sample types; (3) Furthermore,  salinity is the most important environmental factor affecting the microbial community; (4) archaea community might play an important role in nitrogen cycle, while bacterial community might mainly participate in the sulfur cycle, including functions of dark oxidation of sulfur compounds, dark sulfur oxidation and respiration of sulfur compounds. This study is supplementary to the dataset of microbial community structure for hypersaline environments, which will provide important perspectives into the search for life on Mars.

Hypersaline environment,Microbial community structure,Mars analog,16s rRNA gene