连续降雨后太湖流域典型农田土地利用方式下土壤至入湖河流水体细菌群落的变化

研究以太湖区域中林地、桃园、稻田以及链接这些典型土地的河流共8个点为取样地，借助16S rRNA扩增子高通量测序和分析技术，基于Illumina HiSeq测序平台，利用双末端测序的方法得到1 865 862条原始序列，通过对原始序列进行拼接、过滤，得到1 712 497条有效序列，按照97%相似性将优质序列划分为95 132 条可操作分类单元（OTU， operational taxonomic units） ，同时基于OTUs 信息计算Alpha 和Beta 群落丰富度和多样性指数，并采用RDP Classifier结合GreenGene数据库对代表性OTU 序列进行注释。在OTU聚类信息、群落多样性指数及组间差异性物种统计方面，分析了明显连续降雨后监测的细菌群落从农田到河流连续地变化规律。结果表明，森林景观带、稻田、桃园土壤细菌种群多样性明显比河流水体中丰富，说明陆源微生物在迁移过程中发生了适应特定生境的变化。Acidobacteria门在森林景观带、水稻田、桃园中表现出较高的丰度，Proteobacteria门在河流中展现出更大的种群优势。Nitrospirae门是一类具有硝化作用的细菌，在水稻田中显示较高的优势。Yersinia属、Flavobacterium属、Aeromonas属、Pseudomonas属、Acinetobacter属是具有传播水生动物、人畜流行疾病能力的种群，并且在河流中具有较高丰度，应当引起注意。Sphaerotilus属对污水中的有机物和有毒物质有很强的降解作用，在河流中的丰度高于土壤。Sphingomonas属、Arthrobacter属、Thiobacillus属能够降解除草剂、农药等有机污染物，在桃园和稻田中表现出较高丰度，具有环境修复价值。本文为系统掌握太湖流域果园和水稻田土壤细菌群落结构的差异特征，以及土壤微生物群落从农田系统到河流的变化规律提供了理论依据，提示该区域农业从事者应当从经济、生态和健康方面综合考虑土地利用方式。

Variations of Bacterial Community Along Farmland-river Continuum After Continuous Rainfall in Taihu Lake Basin, China

The land of forest,orchard, paddy and the river connected lands in Changzhou and Wuxi City of Taihu Lake basin were selected to monitor the changes of bacterial communities along farmland-river continuum after obvious rainfall. With the help of 16S rRNA high throughput sequencing, 1 865 862 raw sequences were obtained and then 1 712 497 effective sequences were singled out after matching and filtering, 95 132 operational taxonomic units(OTUs) identified basing on a similarity of 97%, which were used for calculating the Alpha and Beta diverse indexes. The phylogenetic affiliation of each representative sequence was analysed by an RDP classifier against the GreenGene database. The results showed that the bacterial community in soil from forest, orchard and paddy field was more diverse than that in the adjacent rivers, indicating the local expression of soil-derived inoculum in rivers. The relative abundance of Acidobacteria was higher in forest, paddy and orchard soil, while the relative abundance of Proteobacteria was higher in rivers. Nitrospirae that has nitrification ability showed much higher abundance in paddy soil. It was worthwhile to note that some genus that could cause diseases in human and animals, e.g. Yersinia, Flavobacterium, Aeromonas, Pseudomonas, Acinetobacter, presented higher abundance in rivers. In addition, the rivers contributed to the establishment of higher abundant Sphaerotilus with the ability to decompose the hazardous organic compounds. On the contrast, the genus of Sphingomonas, Arthrobacter, Thiobacillus that could degrade herbicides and pesticides, presented higher abundance in orchard and paddy field. This study will help us to understand the differences of bacterial community between orchard soil and paddy soil, and provide some valuable fundamental information on how bacterial communities succeed along farmland-river continuum around area of Taihu Lake basin.