天津独流减河流域不同等级河流沉积物细菌区系及功能辨识

细菌群落对环境变化的敏感性较高，但在相似等级的生态条件下其代谢功能或具有趋同性.为探讨微生物群落的这种环境属性并验证其用于流域功能单元划分方面的可行性，本文以天津市独流减河流域上游汇水段河流表层沉积物为研究对象，从河道干流(MS)、左岸支流(LT)和右岸支流(RT)这3个连续的空间单元入手，研究沉积物中细菌的多样性、结构和功能代谢丰度，并探讨其作为流域功能单元划分关键因子的可行性.结果表明，不同等级河流沉积物之间细菌的Shannon指数和Simpson指数无显著差异(P>0.05),但Chao1、 Ace、 Observed＿species和PD＿whole＿tree指数均呈现支流显著高于干流的现象(P<0.05).细菌优势菌门的相对丰度在不同等级河流沉积物中差异不显著，但其功能代谢丰度则表现为干流显著高于支流(P<0.05),而不同支流之间差异不显著(P>0.05).本研究发现，除可交换态磷和硝态氮之外，其他理化性质在不同河流空间单元之间差异不显著，但pH和铁铝结合态磷显著影响了细菌群落的结构组成，有机质和总氮则与细菌功能代谢密切相关.研究同时发现，基于细菌代...

Identification of Bacterial Flora and Metabolic Function of Sediments in Different Channels of Duliujian River Basin, Tianjin

Bacterial communities are highly sensitive to environmental changes, but their metabolic functions may be convergent under similar ecological conditions. In order to test this environmental attribute of the bacterial community and verify the feasibility in using the bacterial metabolic data to divide functional units at the river basin scale, the surface sediments in three continuous spatial units of the main stream (MS), left tributary (LT), and right tributary (RT) of the Duliujian River basin were selected as the research objects. Therefore, 16S rDNA high-throughput sequencing and the PICRUSt platform were used to analyze the bacterial diversity and metabolic function of sediments in different units. The results showed that there were no significant differences for the Shannon and Simpson indices between the different river channels (P>0.05); however, the bacterial diversity indices of Chao1, ACE, Observed_species, and PD_whole_tree of LT and RT were significantly higher than those of the MS (P<0.05). Moreover, the dominant bacterial phyla were not significantly different among the different river channels. In the present study, a total of 41 metabolic pathways were predicted based on the KEGG database, among which 34 metabolic pathways such as membrane transport, amino acid metabolism, and carbohydrate metabolism were significantly different. The functional metabolic abundance was higher in MS than that in RT and LT (P<0.05); however, there was no significant difference between those of RT and LT (P>0.05). Except for exchangeable phosphorus and nitrate nitrogen, there were no significant differences in other physicochemical properties among the different river channels (P>0.05). Furthermore, pH and iron/aluminum-phosphorus were found to significantly affect the bacterial structure, and SOM and TN were found to significantly affect the bacterial metabolic function. Overall, the sediments of MS and tributaries (LT and RT) of the river were clearly divided into level-1 and level-2 groups, indicating that the metabolic abundance of the bacterial community can be used as the key indicator in the division of functional units at the river basin scale. This study provided a theoretical basis and technical support for ecological functional division and management in coastal river basins.