柴达木盆地河流与湖泊水体微生物群落结构及共现网络模式差异

Differences of microbial community structures and co-occurrence networks in rivers and lakes in the Qaidam Basin

摘要:

【目的】 河流与湖泊是重要且紧密联系的水生生态系统，其中微生物是河流与湖泊生态系统中重要的有机组分并参与介导水体各类物质的转化和能量流动，探究河流与湖泊水体细菌和真菌群落特征及其共现网络模式的差异是深入理解柴达木盆地水生生态系统生物地球化学循环的关键。【方法】 基于高通量测序技术利用统计分析，选取柴达木盆地典型河湖(4个湖泊和6条河流)为研究对象，解析河流与湖泊水体的细菌和真菌群落的多样性、群落结构、驱动因素和共现网络的差异性。【结果】 河流水体细菌和真菌的丰度和多样性指数均高于湖泊水体(Wilcoxon，P<0.01)。河流与湖泊水体的细菌群落的最优势菌门均为变形菌门(Proteobacteria，河流占比：6.0%−63.0%；湖泊占比：8.0%−61.0%)，河流与湖泊的真菌群落最优势物种不同，河流为子囊菌门(Ascomycota)：0.5%−75.0%、湖泊为未分类菌门(unclassified_k_Fungi)：3.0%−87.0%。河流与湖泊水体的细菌和真菌群落结构差异显著(细菌：R=0.599，P=0.001；真菌：R=0.435，P=0.001)。海拔(altitude, Alt)、叶绿素a (chlorophyll a, Chl-a)和总氮(total nitrogen, TN)是不同水体的细菌群落结构的显著驱动因子；而溶解氧(dissolved oxygen, DO)、酸碱度(potential of hydrogen potential of hydrogen, pH)和温度(temperature, Temp)是不同水体真菌群落结构的显著驱动因子。细菌和真菌群落在不同生境中稳定性差异较大：河流细菌群落比湖泊细菌群落中更稳定，而湖泊真菌群落比河流真菌群落更稳定。【结论】 柴达木盆地河流与湖泊水体的细菌和真菌群落特征存在较明显差异，表现出一定的空间异质性。本研究可为深入研究柴达木盆地河湖水生生态系统微生物群落特征的差异和联系提供数据支撑，并为该区域水资源保护和管理提供一定理论依据。

关键词:河流与湖泊;细菌和真菌;驱动因素;共现网络

Abstract:

[Objective] Rivers and lakes are important and closely linked aquatic ecosystems, in which microorganisms are important organic components and participate in the transformation of various substances and energy flow. Comparing the bacterial and fungal communities and their co-occurrence networks between rivers and lakes is the key to a deeper understanding of the biogeochemical cycling in aquatic ecosystems of the Qaidam Basin. [Methods] We analyzed the diversity, structures, driving factors, and co-occurrence networks of bacterial and fungal communities in six rivers and four lakes of the Qaidam Basin by next-generation sequencing and statistical analysis methods. [Results] The abundance and diversity of bacteria and fungi in rivers were higher than those in lakes (Wilcoxon, P<0.01). The most dominant bacterial phylum was Proteobacteria in both rivers and lakes (rivers: 6.0%–63.0%; lakes: 8.0%–61.0%), while the most dominant fungal phylum varied between rivers and lakes, being Ascomycota (0.5%–75.0%) in rivers and unclassified_k_Fungi (3.0%–87.0%) in lakes. The structures of bacterial and fungal communities differed between rivers and lakes (bacteria: R=0.599, P=0.001; fungi: R=0.435, P=0.001). Altitude (Alt), chlorophyll a (Chl-a), and total nitrogen (TN) were significant factors shaping bacterial community structures, while dissolved oxygen (DO), pH, and temperature (Temp) were significant drivers shaping fungal community structures in different aquatic ecosystems. The stability of bacterial and fungal communities varied significantly between habitats. Specifically, bacterial communities were more stable in rivers than in lakes, while fungal communities were more stable in lakes than in rivers. [Conclusion] The bacterial and fungal communities varied between rivers and lakes in the Qaidam Basin, demonstrating spatial heterogeneity. This study can provide data support for the in-depth study of the differences and connections of the microbial community characteristics between rivers and lakes in the Qaidam Basin. Moreover, it lays a theoretical foundation for the protection and management of water resources in this region.

Key words:river and lake;bacteria and fungi;driving factors;co-occurrence network