[Bacterioplankton Community Structure in the Lancang River Basin and the Analysis of Its Driving Environmental Factors].

Abstract

In order to explore the bacterioplankton diversity community structure in the Lancang River basin, as well as to study the relationship between the bacterial diversity and environmental factors, MiSeq high-throughput sequencing was used to analyze and compare the bacterial diversity and community composition of samples in February 2017. Furthermore, Pearson correlation analysis and redundancy analysis (RDA) were used to identify the key environmental factors for the change of bacterial community structure in the natural river and reservoirs of the Lancang river. The results show that the ACE index and Shannon index of the natural river are higher than those of the reservoir, and the main environmental factors causing the diversity of planktonic bacteria in natural river and reservoir segments are water temperature (WT), dissolved oxygen (DO), turbidity (Tur), permanganate index, pH, and total nitrogen (TN). Overall, 26772 optimized reads were obtained from samples based on the high-throughput sequencing of the V3 and V4 region of the 16S rRNA gene. The bacterial species detected in these samples cover 45 phyla and 965 genera. Taxonomic assignment analysis indicated that Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria are the abundant phyla. Among them, the Proteobacteria content is relatively rich, accounting for 36%-94% of the bacterial community. The predominant groups are α-Proteobacteria, β-Proteobacteria, and γ-Proteobacteria, at the genus level, with Proteobacteria ratios of 0.39%-21.56%, 0.39%-55.80% and 31.09%-99.18%, respectively. The environmental factors affecting the community structure of planktonic bacteria are different in natural river and reservoir. DO and Tur are the key environmental factors affecting the community structure of planktonic bacteria in the natural river, while the community structure of planktonic bacteria in reservoirs is mainly affected by WT, permanganate index, and TN.