Unravelling the complex influence of dissolved organic matter on microbial diversity in a salinized lake.

Ecosystems in cold and arid regions, such as Dai Lake - a typical inland, salinized lake in the semi-arid region of northern China - face severe environmental challenges, including salinization and biodiversity loss. This study investigates the chemical composition of dissolved organic matter (DOM) and the structure of microbial communities in lake water and sediments, offering novel insights into the ecosystem's dynamics. In winter, DOM in the lake water is primarily derived from decaying plant and animal matter, while sediment DOM is predominantly associated with microbial activity. Statistical analyses revealed significant correlations between DOM components and key microbial species, including Firmicutes, Actinobacteria, α-Proteobacteria, and Acidobacteria (p < 0.05), highlighting the critical role of microbial communities in DOM transformation. Partial least squares structural equation modeling (PLS-SEM), a latent variable approach integrating multiple regression analysis, demonstrates that DOM composition, along with environmental factors such as salinity, temperature, and nutrient levels, significantly influences microbial diversity and community dynamics in the lake. These findings highlight the importance of seasonally adjusting management strategies - such as controlling nutrient inputs, monitoring water quality, and managing sediments - to protect key microbial communities and sustain ecosystem health.