Hu Yang, Bai Chengrong, Cai Jian, Dai Jiangyu, Shao Keqiang, Tang Xiangming, Gao Guang
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences.
University of Chinese Academy of Sciences.
Microbes Environ. 2018 Jul 4;33(2):127-134. doi: 10.1264/jsme2.ME17170. Epub 2018 May 22.
Rivers and their tributaries sculpt the earth's surface, and play an important role in substance circulation and energy flow. Bacteria are involved in most biogeochemical processes in the fluvial ecosystem; however, their pattern distribution in a river and its tributaries has not yet been investigated in detail. In the present study, high-throughput sequencing was employed to examine bacterial communities and their co-occurrence networks between Kaidu River and its nine tributaries in northwestern China. The results obtained demonstrated that both bacterial communities shared a similar dominant sub-community, mainly consisting of Actinobacteria, Bacteroidetes, and Proteobacteria, with Limnohabitans and Variovorax as the dominant genera. In spite of these commonalities, bacterial community structures still significantly differed between these two habitats, which may be related to the distance-related dispersal limitation. Their co-occurrence networks were generally both positively structured. The structural analysis showed that OTUs from the same phyla were more likely to co-occur. Although the keystone genera were taxonomically different between Kaidu River and its tributaries, they both shared common trophic properties in exploiting niches under oligotrophic conditions. We noted that their relative abundances were less than 1%, indicating the over-proportional roles of rare genera in the bacterial community. In addition, the inferred networks showed less nodes and edges, but higher modularity in Kaidu River than its tributaries, suggesting the higher fragmentation of the bacterial community in the mainstream.
河流及其支流塑造了地球表面，并在物质循环和能量流动中发挥着重要作用。细菌参与了河流生态系统中的大多数生物地球化学过程；然而，它们在河流及其支流中的分布模式尚未得到详细研究。在本研究中，采用高通量测序技术来检测中国西北部开都河及其九条支流中的细菌群落及其共生网络。所得结果表明，两个细菌群落共享一个相似的优势亚群落，主要由放线菌门、拟杆菌门和变形菌门组成，其中Limnohabitans和Variovorax为优势属。尽管存在这些共性，但这两个生境之间的细菌群落结构仍存在显著差异，这可能与距离相关的扩散限制有关。它们的共生网络总体上都是正结构。结构分析表明，来自同一门的操作分类单元更有可能共生。尽管开都河及其支流中的关键属在分类学上有所不同，但它们在贫营养条件下利用生态位方面都具有共同的营养特性。我们注意到它们的相对丰度小于1%，这表明稀有属在细菌群落中发挥着超比例的作用。此外，推断出的网络显示，开都河中的节点和边较少，但模块化程度高于其支流，这表明主流中的细菌群落具有更高的碎片化程度。
