嘉陵江（南充段）水体及其底泥中氨氧化微生物群落空间分布特征及其与环境因子关系

为探究人为干扰较多的城市河流中氨氧化微生物的空间变异特征以及影响因素，以嘉陵江（南充段）流域及其城市支流为研究对象，分别采集城市上、中和下游以及流经城区的河流的表层水及其相应底泥，进行理化性质分析和基于16S rRNA基因的Miseq测序分析。结果表明：（1）城市支流水体中的总磷、无机氮和溶解性有机碳显著高于嘉陵江干流。（2）荧光定量PCR分析amoA基因的丰度表明干流中氨氧化古菌（AOA）的丰度总体高于氨氧化细菌（AOB），在水体和底泥中AOA/AOB的比例分别为086~631和179~6985。仅在城市支流水体中AOB的数量高于AOA。（3）嘉陵江水体中主导AOB类群隶属于亚硝化单胞菌属Nitrosomonas cluster 6，而城区支流和靠近排污口的水体和底泥中Nitrosococcus oceani like AOB则为主导AOB类群。（4）水体NH4+-N浓度是影响AOB群落结构空间分布的主导环境因子（P < 005）。（5）该江段中主导AOA类群主要为泉古菌Candidatus Nitrosoarchaeum和Nitrososphaera，且C.Nitrososphaera在城市支流底泥中高度富集。结论综合表明嘉陵江干流和支流氨氧化微生物群落存在显著的空间分异，城市支流及生活污水的汇入是影响其群落特征的主要因素

Spatial Distribution of Ammonia Oxidizing Microorganism in Surface Water and Sediment in Jialing River (Nanchong Section) and Their Relationship with Environmental Factors

Urban rivers represent a unique ecosystem in which anthropic intervention occurs regularly. However, the spatial distribution of ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA) in the urban river has not well documented. Here, a comprehensive analysis of AOA and AOB in the surface water and sediments in Nanchong section of Jialing River and its two urban branches was conducted using 16S rRNA gene based Illumina MiSeq sequencing. Results were as follows: (1) The total phosphorus and inorganic nitrogen of urban branch were significantly higher than those in main Jialing River. (2) Real time quantitative PCR of ammonia monooxygenase (amoA) genes showed that the ratios of AOA/AOB were 086-631 and 179-6985 in surface water and sediment, respectively, which indicating AOA mostly predominated over AOB. But the abundance of AOB in urban branches was much higher than that of AOA. (3) AOB in surface water and sediment in Jialing River were mostly affiliated to Nitrosococcus oceani like lineage，while the dominant AOB in urban branches and drain outlet fell within Nitrosococcus oceani like lineage. (4) Redundancy analysis suggested that NH4+-N content in surface water was the most significant driver determining the AOB community composition in the Jialing River. (5) The AOA community in Jialing River was dominanted by Candidatus Nitrosoarchaeum and Nitrososphaera, the latter was highly enriched in urban branches. Findings highlight that ammonia oxidizers exhibit spatial variations in Jialing River (Nanchong section) and urban branches. The joint influence of sewage discharging and contaminated urban branches could be the main factors to sharp the community of ammonia oxidizing microorganisms.