三峡库区水体中硫氧化菌的群落多样性

Diversity of sulfur-oxidizing bacteria in waters of the Three Gorges Reservoir, China

摘要:

[目的]探究三峡库区干流和支流水体硫氧化菌群落组成和多样性及其与水体理化性质的相关性。[方法]于2017年3月在三峡库区支流和干流共选取9个采样点，测量各采样点水体理化参数，针对水体样品的soxB基因进行系统发育分析、聚类分析和多样性分析，并分析水体理化性质与硫氧化菌群落组成和多样性的相关性。[结果]克隆文库分析显示，本研究的三峡库区水体样品中硫氧化菌分属于α-Proteobacteria和β-Proteobacteria纲，其中β-Proteobacteria的硫氧化菌是群落构成主体，在干流和支流的采样点中相对丰度均高于95.6%。聚类分析和主坐标分析（PCoA）显示，各支流采样点之间以及支流样点和其对应干流样点之间的硫氧化菌群落构成差异较大，而干流采样点间硫氧化菌群落构成差异较小。Mantel检验结果显示，硫氧化菌群落组成与水体的温度、盐度、溶氧量、藻含量和pH等理化参数呈显著（P < 0.05）相关。Pearson相关性分析显示硫氧化菌的群落多样性与藻含量和DIC呈现显著负相关。[结论]三峡库区支流和干流水体中硫氧化菌主要由β-Proteobacteria纲构成，库区干流水体中硫氧化菌群落构成较为相似，而不同支流水体中的硫氧化菌群落构成差异较明显，并且支流和对应干流交汇处的水体中硫氧化菌群落组成差异明显，水体理化性质是导致这一差异的重要原因之一。

Abstract:

[Objective] To explore the composition and diversity of sulfur-oxidizing bacteria (SOB) community and its response to environmental variables in the mainstream and branches of the Three Gorges Reservoir (TGR). [Methods] A total of nine sampling locations were selected along the mainstream and branches of the TGR in March 2017. The physical and chemical parameters were measured on the sampled waters, followed by soxB gene-based phylogenetic analyses. The correlation analysis was performed between the physicochemical properties of the sampled waters and the composition and diversity of sulfur-oxidizing bacterial community. [Results] SOB in the collocted TGR waters belonged to α-Proteobacteria and β-Proteobacteria, with the the latter being dominant (relative abundance was higher than 95.6% in the studied mainstream and branch samples). Cluster analysis and principal coordinate analysis (PCoA) showed that the branch samples are scattered with each other and with their corresponding mainstream sample, while the mainstream sampls are relatively more centralized. The Mantel test showed that the SOB population composition was significantly (P < 0.05) correlated with the measured physicochemical parameters (i.e. water temperature, salinity, dissolved oxygen, algal content and pH) of the water samples. Pearson correlation analysis showed that the community diversity of sulfur-oxidizing bacteria was negatively correlated with algal content and dissolved inorganic carbon (DIC). [Conclusion] The SOB in the branch and mainstream TGR waters mainly belongs to the Proteobacteria. The composition of the SOB populations is similar among the mainstream samples, whereas the SOB population composition in the branch samples differs with each other and with their corresponding mainstream samples. This situation is mainly caused by the characteristic physical and chemical properties of the TGR waters.