[Seasonal Response Features of Microbial Community Structure for Nitrogen Transformation in Inland Lakes on the...

Studying the nitrogen transformation characteristics of microbial communities in the inland lakes of the Qinghai-Xizang Plateau （QXP） is of great significance for a deeper understanding of the nitrogen budget balance and biogeochemical cycling in the regional lake ecosystems. Based on metagenomic sequencing technology， this study constructed a non-redundant gene library of nitrogen-transforming microorganisms and conducted multivariate statistical analysis to explore the characteristics and assembly mechanisms of nitrogen-transforming microbial communities in inland lakes on the QXP. The results indicate： ① Bacteria were the main group of nitrogen transformation microbes in the plateau inland lakes. The dominant bacterial phylum involved in nitrogen conversion both in summer and winter was Pseudomonadota， with an average proportion of 39.35% and 35.09% at different sampling sites in different seasons， respectively. The dominant bacterial genera in summer and winter were Candida_planktophila （the average proportion of different sampling sites was 4.04%） and unclassified_c_Actinomycetes （the average proportion of different sampling sites was 7.91%）. ② Salinity and dissolved oxygen were the most significant environmental factors affecting the microbial community structure of nitrogen transformation in different seasons. There were differences in the process of nitrogen transformation microbial community assembly in different seasons and different sampling lakes. ③ There were differences in the abundance of functional genes of nitrogen transformation microbes in different seasons， and denitrification was the most widely involved process of microbial communities in the plateau inland lakes in different seasons. The environmental factors driving the abundance of nitrogen transformation genes in different seasons were altitude， water temperature， total dissolved solids， and salinity. Overall， there was significant spatiotemporal heterogeneity in the assembly process of nitrogen transformation microbial communities in the plateau inland lakes. The results of this study can provide data support for the understanding of nitrogen-transforming microbes in the plateau inland lake ecosystem and provide a theoretical basis for lake water ecological management and regional greenhouse gas emissions.