三峡水库中段水体微生物群落结构的季节变化

为了探究三峡库区中段水体微生物群落结构的季节变化特征，分别于2018年春季（3月）、夏季（7月）、秋季（9月）、冬季（1月）采集三峡库区中段万州、涪陵、忠县流域表层水样，分析水质指标和微生物群落结构；通过构建16S rRNA基因克隆文库，结合PCR扩增技术进行高通量测序。结果表明，变形菌门（Proteobacteria）、放线菌门（Actinobacteria）、拟杆菌门（Bacteroidetes）、蓝细菌门（Cyanobacteria）是三峡库区中段水体中的优势菌，不同菌门分布呈现明显的季节特征，冬季微生物多样性高于夏季。夏、秋、冬三季中，变形菌门是第一优势菌，占细菌群落的42.63%~92.90%，春季放线菌门的含量相对丰富，占细菌群落的16.65%~42.25%，蓝细菌门在春冬季的含量相对较高，占细菌群落的6.50%~13.50%，夏秋季的含量较低。PCoA和层级聚类分析显示，夏季和秋季微生物群落结构相似度高，冬季和春季的相似度高，且夏秋季和冬春季的多样性存在显著性差异（P=0.01）。RDA分析表明，温度是影响三峡库区中段水体微生物群落结构最主要的环境因子。

Seasonal Variation of Microorganism Community Structure in the Middle Section of Three Gorges Reservoir

Seasonal variation and exploitation of microbial community diversity in the middle section of Three Gorges Reservoir can provide information to regulate Three Georges Reservoir (TGR) more effectively. In this study, we investigated microbial community structure and diversity in the middle section of TGR by constructing a 16S rDNA clone library. The seasonal distribution of the microbial community and its relationship with environmental parameters were then analyzed. The aim was to better understand seasonal variation of microbial community structure in Three Gorges Reservoir. In winter (January), spring (March), summer (July) and autumn (September) of 2018, water samples were collected from TGR at Wanzhou, Fuling and Zhongxian for analysis of water quality parameters and microbial community structure. The 16S rRNA gene clone library was constructed and analyzed by high-throughput sequencing combined with PCR amplification. Results show that Proteobacteria, Actinobacteria, Bacteroidetes and Cyanobacteria were the dominant bacteria taxa in the middle section of the Three Gorges Reservoir, and the distribution of different bacteria phyla clearly varied with season. Proteobacteria was the most dominant taxa in summer, autumn and winter, accounting for 42.63%-92.90% of the total bacteria. Actinobacteria were relatively abundant in spring (16.65%-42.25%), while cyanobacteria were relatively abundant in winter and spring (6.50%-13.50%), but low in summer and autumn. Microbial diversity in winter was higher than in summer, but microbial abundance was higher in summer than in winter. Principal Coordinate Analysis (PCoA) and hierarchical cluster analysis show that microbial community structure in summer and autumn was similar, and similarity in winter and spring was high. Analysis of variance showed that microbial community diversity in summer and autumn were significantly different from in spring and winter (P=0.01). Redundancy Analysis (RDA) showed that water temperature was the primary environmental factor affecting microbial community structure in the middle section of Three Gorges Reservoir.