Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Environ Sci Technol. 2021 Apr 20;55(8):4573-4584. doi: 10.1021/acs.est.0c00915. Epub 2021 Mar 18.
The discovery of complete ammonia oxidation (comammox) has altered our understanding of nitrification, which is the rate-limiting process in the global nitrogen cycle. However, understanding the ecological role of comammox or its contribution to nitrification in both natural and artificial ecosystems is still in its infancy. Here, we investigated the community distribution and function of comammox bacteria in riparian ecosystems and analyzed interactions between comammox and other nitrogen cycling microorganisms. The comammox bacterial abundance and rate were higher in summer than in winter and higher in nonrhizosphere soils than in the rhizosphere. Fringe soils in the riparian zone comprise a comammox hotspot, where the abundance (2.58 × 10 copies g) and rate (0.86 mg N kg d) of comammox were not only higher than at other sampling sites but also higher than those of other ammonia oxidation processes. The comammox rate correlated significantly positively with relative abundance of the comammox species but not with that of the species . Analysis of comammox interaction with other ammonia-oxidizing processes revealed ammonia-oxidizing archaea to dominate interface soils, comammox to dominate in fringe soils, and anaerobic ammonium oxidation (anammox) to dominate in interface sediments of the riparian zone. These results indicate that comammox may constitute an important and currently underestimated process of microbial nitrification in riparian zone ecosystems.
氨氧化（comammox）的发现改变了我们对硝化作用的理解，硝化作用是全球氮循环中的限速过程。然而，对 comammox 的生态作用或其在自然和人工生态系统中对硝化作用的贡献的理解仍处于起步阶段。在这里，我们调查了河岸生态系统中 comammox 细菌的群落分布和功能，并分析了 comammox 与其他氮循环微生物之间的相互作用。comammox 细菌的丰度和速率在夏季高于冬季，在非根际土壤中高于根际。河岸带边缘土壤是 comammox 的热点区域，其 comammox 的丰度（2.58×10 拷贝 g）和速率（0.86mgNkgd）不仅高于其他采样点，而且高于其他氨氧化过程。comammox 的速率与 comammox 种的相对丰度呈显著正相关，但与种的相对丰度无关。comammox 与其他氨氧化过程相互作用的分析表明，氨氧化古菌在界面土壤中占主导地位，comammox 在边缘土壤中占主导地位，而厌氧氨氧化（anammox）在河岸带的界面沉积物中占主导地位。这些结果表明，comammox 可能是河岸带生态系统中微生物硝化作用的一个重要且目前被低估的过程。
