Bacterial community plays a key role in environmental and ecological processes of river ecosystems. Given the special climatic and geographical conditions, studying the compositional characteristics of microorganisms in highland rivers and the relationship between such microorganisms and water physicochemical factors is important for an in-depth understanding of microbial ecological mechanisms. In the present study, high-throughput sequencing was used to investigate and study the bacterioplankton community of the Huangshui River in the ecotone zone of the Qinghai Plateau and Loess Plateau. The results showed that the Huangshui River had significantly lower alpha diversity than the plain rivers. Despite the similarity in their environmental conditions, the main taxonomic compositions of the bacterial communities were distinct between the Huangshui River and polar regions (the Arctic and Antarctica). Proteobacteria accounted for the largest proportion (30.79–99.98%) of all the sequences, followed by Firmicutes (0–49.38%). Acidiphilium was the most numerous genera, which accounted for 0.03–86.16% of the assigned 16S reads, followed by Acidocella (0–95.9%), both belonging to Alphaproteobacteria. The diverse taxa of potential pathogens, such as Acinetobacter, Pseudomonas, and Aeromonas, were also identified. A principal coordinates analysis, coupled with a canonical correspondence analysis, showed spatial variations in the bacterial community composition. The water physical properties (e.g., Cr⁶⁺, total phosphorus, and COD_Mn); altitude; and land use (e.g., urban land cover and aquaculture) determined the distribution of the bacterioplankton composition. PICRUSt2 revealed that the overall functional profiles of the bacterial communities in different samples were similar, and our results suggested the potential health risks of water sources in this area. This work provided valuable insight into the composition of the plankton bacterial community and its relationship with the environmental factors in the Huangshui River in the ecotone zone of the Qinghai Plateau and Loess Plateau and a theoretical foundation for ecological health management.

中文翻译：

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湟水河浮游细菌群落组成、功能特征及影响因素

细菌群落在河流生态系统的环境和生态过程中起着关键作用。鉴于特殊的气候和地理条件，研究高原河流微生物的组成特征及其与水体理化因素的关系，对于深入了解微生物生态机制具有重要意义。本研究采用高通量测序技术对青海高原和黄土高原交错带湟水河浮游细菌群落进行调查研究。结果表明，湟水河的α多样性显着低于平原河流。尽管它们的环境条件相似，细菌群落的主要分类组成在湟水河和极地地区（北极和南极洲）之间是不同的。Proteobacteria 占所有序列的最大比例（30.79-99.98%），其次是 Firmicutes（0-49.38%）。Acidiphilium是数量最多的属，占分配的 16S 读数的0.03-86.16% ，其次是Acidocella (0-95.9%)，均属于 Alphaproteobacteria。还鉴定了潜在病原体的不同分类群，例如不动杆菌属、假单胞菌属和气单胞菌属。主坐标分析与规范对应分析相结合，显示了细菌群落组成的空间变化。水的物理性质（例如 Cr ⁶⁺、总磷和 COD _Mn); 高度; 和土地利用（例如，城市土地覆盖和水产养殖）决定了浮游细菌组成的分布。PICRUSt2 显示不同样本中细菌群落的整体功能特征相似，我们的结果表明该地区水源存在潜在的健康风险。这项工作为了解青海高原和黄土高原交错带湟水河浮游生物细菌群落组成及其与环境因子的关系提供了宝贵的见解，为生态健康管理提供了理论基础。