College of Water Sciences, Beijing Normal University, Beijing 100875, China.
College of Water Sciences, Beijing Normal University, Beijing 100875, China.
Water Res. 2021 Nov 1;206:117774. doi: 10.1016/j.watres.2021.117774. Epub 2021 Oct 15.
The recent discovery of complete ammonia oxidation (comammox) has increased our understanding of nitrification. Although comammox has been shown to play an important role in plain wetland ecosystems, studies of comammox contribution are still limited in plateau wetland ecosystems. Here, we analyzed the abundance, activity, community and biogeochemical mechanisms of the comammox bacteria in Yunnan-kweichow and Qinghai-Tibet plateau wetlands from elevations of 1000-5000 m. Comammox bacteria were widely distributed in all 16 sediment samples with abundances higher than 0.96 ± 0.26 × 10 copies g (n = 16). Comammox showed high activity (1.18 ± 0.17 to 1.98 ± 0.08 mg N kg d) at high-elevation (3000-5000 m) and dominated the nitrification process (activity contribution: 37.20 - 60.62%). The activity contribution of ammonia-oxidizing bacteria (1.07 ± 0.08 to 2.79 ± 0.35 mg N kg d) dominated the nitrification process (44.55 - 64.15%) in low-elevation (1000-3000 m) samples. All detected comammox Nitrospira belonged to clade A, while clade B was not detected. Elevation always had a strongest effect on key comammox species. Thus, we infer that elevation may drive the high relative abundance of the species Candidatus Nitrospira nitrificans (avg. 12.40%) and the low relative abundance of the species Nitrospira sp. SG-bin2 (avg. 4.75%) in high-elevation samples that showed a high comammox activity (avg. 1.62 mg N kg d) and high contribution (avg. 46.08%) to the nitrification process. These results indicate that comammox may be an important and currently underestimated microbial nitrification process in plateau wetland ecosystems.
最近发现的完全氨氧化（comammox）增加了我们对硝化作用的理解。虽然 comammox 已被证明在平原湿地生态系统中发挥着重要作用，但在高原湿地生态系统中，对 comammox 贡献的研究仍然有限。在这里，我们分析了从海拔 1000-5000 米的云南-贵州高原湿地和青藏高原湿地的 16 个沉积物样本中 comammox 细菌的丰度、活性、群落和生物地球化学机制。comammox 细菌广泛分布于所有 16 个沉积物样本中，丰度高于 0.96±0.26×10 拷贝 g（n=16）。comammox 在高海拔（3000-5000 米）表现出高活性（1.18±0.17-1.98±0.08mgNkgd），并主导硝化过程（活性贡献：37.20-60.62%）。氨氧化细菌的活性贡献（1.07±0.08-2.79±0.35mgNkgd）主导了低海拔（1000-3000 米）样本中的硝化过程（44.55-64.15%）。所有检测到的 comammox Nitrospira 都属于 clade A，而 clade B 未被检测到。海拔总是对关键的 comammox 物种有最强的影响。因此，我们推断，海拔可能导致高海拔样本中相对丰度较高的种 Candidatus Nitrospira nitrificans（平均 12.40%）和相对丰度较低的种 Nitrospira sp. SG-bin2（平均 4.75%），这些样本表现出较高的 comammox 活性（平均 1.62mgNkgd）和对硝化过程的较高贡献（平均 46.08%）。这些结果表明，在高原湿地生态系统中，comammox 可能是一个重要的、目前被低估的微生物硝化过程。
