Characteristics of bacterial community in Le'an River in winter based on high-throughput sequencing

Abstract:

[Objective] The aims of this study were to analyze the compositional changes of bacterial community in Le'an River from upstream to downstream, and to reveal the main environmental factors shaping the bacterial community. [Methods] The hydrochemical indicators in different reaches, such as C, N, P, Cu, Zn, As and Pb, were measured. High-throughput sequencing of 16S rRNA gene was used to profile the bacterial community structure. Non-metric Multidimensional Scale (NMDS) Analysis and Cluster Analysis of sampling sites based on Bray-Curtis distance were used to explore the bacterial community structure along Le'an River. Redundancy analyzed (RDA) was used to analyze the relationship between environmental factors and bacterial communities. [Results] The concentrations of C, N, P, Cu, Zn, As and Pb were higher in the middle and lower reaches than those in the upper reaches. The diversity of bacterial communities decreased in the middle reaches because of the wastewater from the Dexing Copper Mine, and the richness and diversity increased in the lower reaches because of the wastewater from the agricultural and domestic wastewater. The predominant bacteria composition was Beta-proteobacteria (53.03%), Actinobacteria (20.24%) and Bacteroidetes (14.75%). Due to the influence of Dexing Copper Mine, the abundance of Beta-proteobacteria increased in the middle reaches, while the abundance of Actinobacteria decreased. In the lower reaches, the abundance of Bacteroidetes decreased due to the inter-microbial predation. In the relationship between the bacterial community and environmental factors, dissolved oxygen (DO) was the best environmental factor explaining the changes of bacterial community structure along the Le'an River. [Conclusion] Wastewater from the Dexing Copper Mine in the middle reaches of Le'an River and the agricultural and domestic wastewater in the middle and lower reaches changed the bacterial community structure, resulting the significant changes of the bacterial community along Le'an River. These findings provide a reference for revealing the influences of human activities on the water ecology of the Le'an River.