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On Earth, salt environments are the most relevant analogues to Martian salt deposits with regard to the search for preserved biomolecules. In this study, we analyzed the distribution of lipids in salt samples from Dalangtan and Qarhan in the Qaidam Basin, which is the most important area to carry out analog research of Mars in China. Furthermore, we compared the lipids distribution results with that from other typical Martian analog sites such as the Atacama Desert. Salt samples in the Qaidam Basin are enriched with fatty acid compounds, including normal fatty acids, unsaturated fatty acids, branched fatty acids, and acyclic isoprene acids. In addtion, glycerol dialkyl glycerol tetraethers (GDGTs) and archaeol compounds were also detected in these salt samples. Compared with the hypersaline samples, the clay samples not only have higher abuandance of fatty acids, GDGTs and archaeol compounds, but also a more diversed lipids composition. Only a few lipids were detected in the pure-saline samples, such as archaeol compounds. These clues suggest that content of salt minerals is the major factor affecting the distribution of lipids. This study provides an analogy for detecting and evaluating the traces of life that may exist on Mars. [ABSTRACT FROM AUTHOR]

Over the past 150 million years, the Chilean Atacama Desert has been transformed into one of the most inhospitable landscapes by geophysical changes, which makes it an ideal Mars analog that has been explored for decades. However, a heavy rainfall that occurred in the Atacama in 2017 provides a unique opportunity to study the response of resident extremophiles to rapid environmental change associated with excessive water and salt shock. Here we combine mineral/salt composition measurements, amendment cell culture experiments, and next-generation sequencing analyses to study the variations in salts and microbial communities along a latitudinal aridity gradient of the Atacama Desert. In addition, we examine the reshuffling of Atacama microbiomes after the rainfall event. Analysis of microbial community composition revealed that soils within the southern arid desert were consistently dominated by Actinobacteria, Chloroflexi, Proteobacteria, Firmicutes, Bacteroidetes, Gemmatimonadetes, Planctomycetes, and Acidobacteria, and Verrucomicrobia. Intriguingly, the hyperarid microbial consortia exhibited a similar pattern to the more southern desert. Salts at the shallow subsurface were dissolved and leached down to a deeper layer, challenging indigenous microorganisms with the increasing osmotic stress. Microbial viability was found to change with aridity and rainfall events. This study sheds light on the structure of xerotolerant, halotolerant, and radioresistant microbiomes from the hyperarid northern desert to the less arid southern transition region, as well as their response to changes in water availability. [ABSTRACT FROM AUTHOR]