Limited Microbial Contribution in Salt Lake Sediment and Water to Each Other’s Microbial Communities

Climate change and human activities have led to frequent exchanges of sedimentary and aquatic microorganisms in lakes. However, the ability of these microorganisms to survive in their respective habitats between saline lake sediment and water remains unclear. In this study, we investigated microbial sources and community composition and metabolic functions in sediments and water in Yuncheng Salt Lake using a combination of source tracking and Illumina MiSeq sequencing. The results showed that 0.10–8.47% of the microbial communities in the sediment came from the corresponding water bodies, while 0.12–10.78% of the sedimentary microorganisms contributed to the aquatic microbial populations, and the microbial contributions depended on the salinity difference between sediment and water. Habitat heterogeneity and salinity variations led to the differences in microbial diversity, community composition, and assembly between sediment and water communities. The assembly of sedimentary communities was mainly controlled by stochastic processes (>59%), whereas the assembly of aquatic communities was mainly controlled by deterministic processes (>88%). Furthermore, sediments had a higher potential for metabolic pathways related to specific biogeochemical functions than lake water. These results provide insights into the survival ability of microorganisms and the mechanisms of microbial community assembly under frequent exchange conditions in saline lakes.