秦皇岛新开河河口邻近海域细菌多样性及其影响因子

Impacts of environmental factors on bacterial diversity of Xinkai river estuary in the coastal area of Qinhuangdao

摘要:

【目的】分析秦皇岛新开河河口及其邻近海域3个站位的细菌多样性，了解入海口污染对微生物多样性的影响，为该海域微生物的生态功能研究提供理论基础。【方法】于2014 8月选取秦皇岛新开河入海河口(XKH)及其邻近海域(W1，W2)共3个站位采集水样，采用荧光显微镜计数以及构建16S rRNA基因克隆文库的方法，分析细菌群落结构多样性与海水环境条件的关系。【结果】邻近海域W1站位的细菌总数(2.62×106 cells/mL)和多样性均高于新开河河口XKH站位(细菌总数：6.62×105 cells/mL)和W2站位(细菌总数：2.02×106 cells/mL)；从XKH、W1、W2 3个站位的16S rRNA基因克隆文库中分别获得57、89、87条有效序列，按97%的序列相似性分别划分为46、51、56个OTU，分别属于Proteobacteria、Cyanobacteria、Bacteroidetes、Firmicute、Actinobacteria、Planctomycetes和Verrucomicrobia七个门。其中在XKH和W2站位中，Proteobacteria门的克隆子分别占总克隆数的50.9%和75.9%，是最优势的类群，分属于Alphaproteobacteria、Betaproteobacteria、Gammaproteobacteria、Deltaproteobacteria和Epsilonproteobacteria纲；在W1站位中，Cyanobacteria门的克隆子占总克隆数的38.2%，是该站位的最优势类群，这些优势类群可通过利用水体中的氮等营养来调节水体生态环境。影响细菌群落分布的环境因子主要为溶解氧、pH和氮营养盐。【结论】秦皇岛新开河河口及其邻近海域的细菌具有丰富的多样性，处于河口海域过渡带的水样具有更高的多样性，细菌群落多样性的分布受氮营养盐的影响更为显著。

Abstract:

[Objective] The goal of this study is to reveal the dynamics of bacterial communities and their relationship with environmental variables through analysis of 16S rRNA gene clone libraries derived from the three stations of Xinkai River estuary for better understanding the ecological functions of this region. [Methods] In August 2014, water samples were collected from 3 stations of Xinkai River estuary (XKH) area and its adjacent water in the coast of Qinhuangdao. Bacterial abundance was estimated using a fluorescence microscope and 16S rRNA gene clone libraries derived from the total bacterial DNA of the water samples. [Results] Total number of bacteria (2.62×106 cells/mL) and diversity of station W1 were higher than that of Xinkai River estuary XKH station (6.62×105 cells/mL) and the station W2 (2.02×106 cells/mL); 16S rRNA gene clone libraries of the stations XKH, W1, and W2 yielded 46, 51 and 56 OTUs, respectively. Those OTUs belonged to the members of 7 different bacterial phyla: Proteobacteria, Cyanobacteria, Bacteroidetes, Firmicutes, Actinobacteria, Planctomycetes and Verrucomicrobia. Proteobacteria was the predominant taxa in the clone libraries of the stations XKH (50.9%) and W2 (75.9%). On the other hand, members of Cyanobacteria were the predominant taxa (38.2%) in the station W1. These dominant groups were closely related to availability of nitrogen and other nutrients of water column. The environmental factors, which affected the distribution of bacterial communities, were dissolved oxygen, pH and nitrogen nutrients. [Conclusion] Xinkai River estuary and its adjacent seawater contained rich bacterial diversity. Particularly, the water samples from the transition zone between the estuary and the sea harbored much higher bacterial diversity. Distribution of bacterial communities was largely regulated by nitrogen nutrients.