Abstract：
Brownification in aquatic ecosystems under global change has attracted attention. The composition and quantity of dissolved organic matter transported from various land use types to lakes differ significantly, causing varying ecological effects of lake brownification by region. Bacterial communities make a significant contribution to the material cycle of ecosystems and are sensitive to environmental changes. In this study, a series of mesocosm systems were used to simulate forest lakes and urban lakes with different degrees of brownification, and a high-throughput amplicon sequencing technique was used to explore the changes in the composition, structure, and function of bacterial communities in shallow lakes undergoing brownification. Principal coordinate analysis (PCoA) and Jensen‒Shannon distance typing analysis both indicated significant differences in bacterial communities between forest lakes and urban lakes. The α diversity of bacterial communities in urban lakes increased with the degree of brownification. However, whether forest lakes or urban lakes, brownification increased the abundance of carbon cycling-related bacterial phyla (Proteobacteria, Poribacteria, and Chloroflexi) and nitrogen cycling-related bacterial genera (Microbacteriaceae, Limnohabitans, Comamonadaceae, Bacillus, and Rhizobiales_Incertae_Sedis). Additionally, the carbon and nitrogen cycling functions of bacterial communities in forest lakes are dominant, while those in urban lakes are dominated by functions related to light. Our study has preliminarily revealed that lake brownification promotes the growth of carbon and nitrogen cycling microorganisms, providing a new paradigm for understanding the response of lake ecosystems in different catchment areas to environmental changes and the carbon and nitrogen cycling processes in shallow lake ecosystems.
摘要：
全球变化下水生生态系统中的布朗效应引起了人们的关注。从各种土地利用类型运输到湖泊的溶解有机物的组成和数量差异很大，造成不同区域湖泊褐化的生态效应。细菌群落对生态系统的物质循环做出重大贡献，并且对环境变化敏感。在这项研究中,一系列的中观系统被用来模拟不同程度的森林湖泊和城市湖泊，并采用高通量扩增子测序技术探索组成变化，结构,浅水湖泊中细菌群落的功能。主坐标分析（PCoA）和Jensen-Shannon距离分型分析均表明森林湖泊和城市湖泊之间的细菌群落存在显着差异。城市湖泊细菌群落的α多样性随着褐化程度的增加而增加。然而,无论是森林湖泊还是城市湖泊，褐化增加了与碳循环相关的细菌门的丰度(变形杆菌，Poribacial,和氯氟菌）和氮循环相关的细菌属（微细菌科，Limnohabitans,Comamonadaceae,芽孢杆菌,和根瘤菌属酶_Incertae_Sedis）。此外,森林湖泊中细菌群落的碳和氮循环功能占主导地位，而城市湖泊中的湖泊则以与光有关的功能为主导。我们的研究初步揭示了湖泊褐化促进了碳氮循环微生物的生长,为了解不同流域湖泊生态系统对环境变化的响应以及浅水湖泊生态系统的碳氮循环过程提供了新的范式。
