The composition of microbial communities varies considerably across ecological environments, particularly in extreme environments, where unique microorganisms are typically used as the indicators of environmental conditions. However, the ecological reasons for the differences in microbial communities remain largely unknown. Herein, we analyzed taxonomic and functional community profiles via high-throughput sequencing to determine the alkaline saline soil bacterial and archaeal communities in the Qarhan Salt Lake area in the Qinghai–Tibet Plateau. The results showed that Betaproteobacteria (Proteobacteria) and Halobacteria (Euryarchaeota) were the most abundant in the soils of this area, which are common in high salinity environments. Accordingly, microbes that can adapt to local extremes typically have unique metabolic pathways and functions, such as chemoheterotrophy, aerobic chemoheterotrophy, nitrogen fixation, ureolysis, nitrate reduction, fermentation, dark hydrogen oxidation, and methanogenesis. Methanogenesis pathways include hydrogenotrophic methanogenesis, CO2 reduction with H2, and formate methanogenesis. Thus, prokaryotic microorganisms in high salinity environments are indispensable in nitrogen and carbon cycling via particular metabolic pathways.

Microbial metabolism is the driving force for biogeochemical cycles in the biosphere. The composition of microbial communities varies greatly in various ecological environments, particularly in extreme environments where animals and plants cannot survive. Unique microorganisms are often used as indicators to reflect environmental conditions, but the ecological reasons for the differences in microbial communities are still largely unknown. Here, we analyzed taxonomic and functional community profiles via high-throughput sequencing to determine the alkaline saline soil bacterial and archaeal communities in the Qarhan Salt Lake area in the Qinghai-Tibet Plateau. The results showed that Betaproteobacteria (Proteobacteria) and Halobacteria (Euryarchaeota) were most abundant in the soils of this area, which are most common in high salinity environments. Accordingly, microorganisms in this area that can adapt to local extremes often have functions such as chemoheterotrophy, aerobic chemoheterotrophy, nitrogen fixation, ureolysis, nitrate reduction, fermentation, methanogenesis, hydrogenotrophic methanogenesis, methanogenesis by CO2 reduction with H2, methanogenesis using formate, and dark hydrogen oxidation. There is no doubt that prokaryotic microorganisms in high salinity environments play an irreplaceable role in nitrogen and carbon cycling through special metabolic pathways.