Diversity and structure of bacterial and archaeal communities in a carbonate-salt lake， Chali Co Lake in Tibet

Chali Co Lake is a high-altitude （4650 m） carbonate-salt lake located in the Qinghai-Tibet Plateau. The community structure composition of bacteria and archaea involved is still unclear. This study employed high-throughput Illumina sequencing to analyze the diversity of bacteria and archaea in Chali Co Lake. By a 97% similarity level， operational taxonomic units （OTUs） were noted and analyzed based on the phylum， class， order， and genus level， respectively. The Redundancy analysis （RDA） was employed to examine the relationship between the dominant genus and environmental factors. A total of 37 phyla， 54 classes， 78 orders， and 417 genera （1，678 OTUs） of bacteria， and 10 phyla， 9 classes， 15 orders， and 32 genera （526 OTUs） of archaea were identified. The predominant bacterial genus were Pelobacter （4.60% to 9.58%）， Aquiflexum （1.08% to 13.97%）， Desulfurivibrio （0.64% to 8.07%） and Desulfocapsa （6.87%）； The dominant archaeota genera were Woesearchaeota AR16 （72.60% to 86.31%）、AR18 （2.71% to 6.45%） and AR15 （0.26% to 6.19%）. Significant correlation between the bacterial community structure and the concentrations of TS， HCO3-， and SO42- （PPelobacter exhibited a significant correlation with T， TN， and Na+ concentrations. Aquiflexum demonstrated a significant correlation with TOC， TN， and temperature. Additionally， both Desulfurivibrio and Desulfocapsa exhibited correlations with temperature， SO42-， and HCO3- concentrations. The structure of archaeal communities was most strongly correlated with K+， TS， and pH. The dominant genera AR16 and AR18 subgroups of archaea exhibited a significant correlation with TP， Mg2+， and K+. The AR15 subgroup demonstrated a significant correlation with TOC， TN， and SO42-. This study revealed the community structure of bacteria and archaea and their species diversity in Chali Co Lake， and provided a theoretical basis for developing halophilic bacteria and exploiting microbial resources.