Abstract

The abundance and community structure of nirS-encoding and nirK-encoding denitrifiers inhabiting the sediment of the Pearl River Estuary was examined with quantitative PCR and high-throughput MiSeq sequencing. The results indicated that the low-oxygen condition (around 4 mg/L) of the Pearl River Estuary was the suitable environment for the denitrifying bacterial growth, and the abundances of nirS-encoding and nirK-encoding denitrifier were both highest in station P3, while the diversity and evenness were highest in stations P2 and P4, respectively. In addition, gene abundance and diversity of nirS was higher than nirK, which indicated that the denitrifying potential of nirS-encoding denitrifiers were significantly greater than that of nirK-encoding denitrifiers (p < 0.05). The most dominant nirS-encoding denitrifiers present in the sediment samples belonged to the phylum Proteobacteria, followed by Chloroflexi. However, the dominant classes of Betaproteobacteria and Gammaproteobacteria showed obvious salinity heterogeneity along the Pearl River Estuary. Betaproteobacteria have a strong survival ability in oligohaline environments and Gammaproteobacteria were opposite. Additionally, the distribution of both Betaproteobacteria and Gammaproteobacteria positively correlated with TOC and \({\text{NO}}_{2}^{ - }.\) For nirK-encoding denitrifiers, the distribution of cluster A and cluster C also showed salinity heterogeneity; the former favored oligohaline environments and the latter were opposite.

中文翻译：

---

珠江口表层沉积物中Nir S-编码和nir K-编码反硝化剂的分布规律

摘要

通过定量PCR和高通量MiSeq测序，研究了居住在珠江口沉积物中的Nir S编码反硝化剂和nir K编码反硝化菌的丰度和群落结构。结果表明，珠江口低氧条件（约4 mg / L）是反硝化细菌生长的适宜环境，nir S编码和nir K编码反硝化菌的丰度均最高。 P3，而站P2和P4的多样性和均匀性最高。另外，nir S的基因丰度和多样性均高于nir K，这表明Nir S的反硝化潜能。编码Nir的反硝化剂明显大于编码Nir的反硝化剂（p <0.05）。沉积物样品中存在的最主要的编码Nir S的反硝化剂属于Proteobacteria门，其次是Chloroflexi。但是，沿珠江河口，β-变形杆菌和γ-变形杆菌的优势类别显示出明显的盐度异质性。Betaproteobacteria在寡盐环境中具有很强的生存能力，而Gammaproteobacteria则相反。此外，这两种β-变形菌和γ-变形菌的分布与正相关TOC和\（{\文本{NO}} _ {2} ^ { - }。\）对于NIR编码K的反硝化剂，簇A和簇C的分布也显示出盐度异质性。前者偏爱寡盐环境，而后者则相反。