Anaerobic ammonium oxidation (anammox) is an important pathway for the removal of fixed nitrogen from aquatic and terrestrial ecosystems. Previous studies on anammox were focused on the surface sediments in estuaries, but the activity and community composition of anammox bacteria in the estuarine subsurface sediments remained unknown. In this study, we used high-throughput sequencing of 16S rRNA gene combined with ¹⁵N isotope tracing method to investigate the activity, diversity, and spatio-temporal distribution of anammox bacteria in sediment cores of the Pearl River Estuary (PRE). Our results indicated that anammox in the subsurface sediments has significant potential activity, contributing to approximately 17.49% of the total microbial nitrogen loss. A variety of anammox bacteria, including Candidatus Scalindua, Ca. Brocadia, Ca. Jettenia, and Ca. Kuenenia, were all detected in the subsurface sediments. Moreover, the anammox bacterial community had a significant specific geographic distribution but no obvious difference along the sediment depth. Multiple environmental factors including salinity, and NH₄⁺ and NO₃⁻ contents, synergistically shaped the diversity and distribution of anammox bacteria in PRE sediments.

中文翻译：

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珠江口沉积物核中厌氧氨氧化（厌氧氨化）细菌的活性，丰度和群落组成

厌氧铵氧化（厌氧氨）是从水生和陆地生态系统中去除固定氮的重要途径。以前关于厌氧氨水的研究集中在河口的表层沉积物上，但是在河口地下沉积物中厌氧菌的活性和群落组成仍然未知。在这项研究中，我们使用高通量的16S rRNA基因测序与¹⁵ N同位素示踪方法相结合，以研究珠江口（PRE）沉积物中厌氧细菌的活性，多样性和时空分布。我们的结果表明，地下沉积物中的厌氧氨氧化具有明显的潜在活性，约占微生物总氮损失的17.49％。多种厌氧菌，包括暂定Scalindua，Ca的 加利福尼亚布罗卡迪亚 杰特尼亚和Ca。Kuenenia，都在地下沉积物中检测到。而且，厌氧细菌群落具有明显的特定地理分布，但沿沉积物深度没有明显差异。多种环境因素，包括盐度，和NH ₄ ⁺和NO ₃ ^-含量，协同形PRE沉积物的多样性和厌氧氨氧化菌的分布。