崇明东滩夏季沉积物厌氧氨氧化菌群落结构与空间分布特征

为探索长江口崇明东滩表层沉积物中是否存在厌氧氨氧化菌以及厌氧氨氧化菌的群落结构与空间分布特征,以崇明东滩高、中、低潮滩夏季表层沉积物中总DNA为模板,PCR扩增沉积物样品中厌氧氨氧化菌特异性16S rDNA片段,通过克隆、测序,构建相应基因文库,将文库中有效克隆序列分别提交到GenBank中进行相似序列搜索,并利用MEGA5绘制系统发育树.分析结果发现,克隆序列CM-L-7和CM-L-18与已发现厌氧氨氧化菌Candidatus"Scalindua sp."同源性达98%,CM-L-13与Candidatus"Scalindua wagneri"同源性达94%,CM-M-6与Candidatus"Kuenenia sp."同源性达94%,CM-M-22与Anaerobicammonium-oxidizing planctomycete JMK-1的同源性达95%,CM-H-15与Candidatus"Kuenenia stuttgartiensis"的同源性达94%.表明,崇明东滩高、中、低潮滩表层沉积物中均存在厌氧氨氧化菌,但所属菌属不同,低潮滩以Candidatus"Scalindua"为主,中、高潮滩以Candidatus"Kuenenia"为主.相比之下,中潮滩厌氧氨氧化菌群落结构较为复杂.部分克隆序列与已发现厌氧氨氧化菌存在较大进化距离,表明崇明东滩可能还存在其他具有潜在厌氧氨氧化功能的细菌.

Community Structure and Spatial Distribution of Anaerobic Ammonium Oxidation Bacteria in the Sediments of Chongming Eastern Tidal Flat in Summer

The objectives of this study were to identify whether there were Anaerobic Ammonium Oxidation (ANAMMOX) bacteria in the surface sediments of Chongming eastern tidal flat in the Yangtze estuary and the feature of their community structure and spatial distribution. Based on the total DNA extracted from the surface sediments of Chongming eastern tidal flat, ANAMMOX-specific 16S rDNA fragments were amplified. PCR products were cloned and sequenced, and an ANAMMOX-specific 16S rDNA gene library was established. Phylogenetic tree was constructed using MEGA5 after the sequences were checked in the GenBank database. Phylogenetic analysis indicated that the clone sequences CM-L-7 and CM-L-18 had 98% identities with ANAMMOX bacteria Candidatus 'Scalindua sp.'. CM-L-13 had 94% identities with Candidatus 'Scalindua wagneri'. CM-M-6 had 94% identities with Candidatus 'Kuenenia sp.'. CM-M-22 had 95% identities with Anaerobic ammonium-oxidizing planctomycete JMK-1. CM-H-15 had 94% identities with Candidatus 'Kuenenia stuttgartiensis'. The results indicated that there were ANAMMOX bacteria in the surface sediments of Chongming eastern tidal flat, but the ANAMMOX species were diverse in different tidal flats: Candidatus 'Scalindua' was the predominant group in the low tidal flat, while Candidatus 'Kuenenia' was the major population in the high tidal flat and the middle tidal flat. In comparison with the high and low tidal flats, the community structure of ANAMMOX bacteria in the middle tidal flat was the most complicated. A portion of the sequences related to uncultivated bacteria outside the known ANAMMOX cluster, probably indicated that there were potential ANAMMOX bacteria in the sediments of Chongming eastern tidal flat.