Spatial and temporal variations related to hydric seasonality in abundance and diversity of denitrifier communities were examined in sediments taken from two sites differing in nitrate concentration along a stream Doñana National Park during a 3-year study. We found a positive relationship between the relative abundance of denitrifiers, determined as narG, napA, nirK, nirS and nosZ denitrification genes, and sediment nitrate content, with similar spatial and seasonal variations. However, we did not find association between denitrification activity and the community structure of denitrifiers. Because nosZ showed the strongest correlation with the content of nitrate in sediments, we used this gene as a molecular marker to construct eight genomic libraries. Analysis of these genomic libraries revealed that diversity of the nosZ-bearing communities was higher in the site with higher nitrate content. Regardless of nitrate concentration in the sediments, the Bradyrhizobiaceae and Rhodocyclaceae were the most abundant families. On the contrary, Rhizobiaceae was exclusively present in sediments with higher nitrate content. Results showed that differences in sediment nitrate concentration affect the composition and diversityof nosZ-bearing communities.

中文翻译：

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硝酸盐含量不同的沉积物中反硝化菌群落丰度和结构的时空变化。

在一项为期 3 年的研究中，对取自 Doñana 国家公园河流沿线的两个硝酸盐浓度不同的地点的沉积物进行了与反硝化菌群落丰度和多样性的水季节性相关的时空变化。我们发现反硝化菌的相对丰度（确定为narG、napA、nirK、nirS和nosZ反硝化基因）与沉积物硝酸盐含量之间存在正相关关系，具有相似的空间和季节变化。然而，我们没有发现反硝化活性与反硝化菌群落结构之间存在关联。因为nosZ显示与沉积物中硝酸盐含量的最强相关性，我们使用该基因作为分子标记构建了八个基因组文库。对这些基因组文库的分析表明，在硝酸盐含量较高的地点，携带nosZ的群落的多样性较高。无论沉积物中硝酸盐的浓度如何，慢生根瘤菌科和红环菌科是最丰富的科。相反，根瘤菌科仅存在于硝酸盐含量较高的沉积物中。结果表明，沉积物硝酸盐浓度的差异影响着nosZ类群落的组成和多样性。