Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, People's Republic of China.
Department of Biogeochemistry, Max Planck Institute for Marine Microbiology, Bremen, Germany.
Environ Microbiol. 2018 May;20(5):1723-1738. doi: 10.1111/1462-2920.14098. Epub 2018 Apr 6.
The distribution and importance of anaerobic ammonium oxidation (anammox) and nitrite-dependent anaerobic methane oxidation (n-damo) have been identified in aquatic ecosystems; their role in agricultural upland soils however has not yet been well investigated. In this study, we examined spatio-temporal distributions of anammox and n-damo bacteria in soil profiles (300 cm depth) from an agricultural upland. Monitoring nitrogen (N) conversion activity using isotope-tracing techniques over the course of one year showed denitrification (99.0% N-loss in the winter and 85.0% N-loss in the summer) predominated over anammox (1.0% N-loss in the winter and 14.4% N-loss in the summer) and n-damo (0.6% N-loss in the winter) in surface soils (0-20 cm). While below 20 cm depth, N-loss was dominated by anammox (79.4 ± 14.3% in the winter and 65.4 ± 12.5% in the summer) and n-damo was not detected. Phylogenetic analysis showed that Candidatus Brocadia anammoxidans dominated the anammox community in the surface soil and Candidatus Brocadia fulgida dominated below 20 cm depth. Dissimilatory nitrate reduction to ammonium (DNRA), another nitrite reduction process, was found to play a limited role (4.9 ± 3.5%) in the surface soil compared with denitrification; below 80 cm DNRA rates were much higher than rates of anammox and denitrification. Ammonium oxidation was the main source of NO2- above 80 cm (70.9 ± 23.3%), the key influencing factor on anammox rates, and nitrate reduction (100%) was the main NO2- source below 80 cm. Considering the anammox, n-damo and denitrification rates as a whole in the sampled soil profile, denitrification is still the main N-loss process in upland soils.
在水生生态系统中，已经确定了厌氧氨氧化（anammox）和亚硝酸盐依赖型厌氧甲烷氧化（n-damo）的分布和重要性；然而，它们在农业旱地土壤中的作用尚未得到很好的研究。在这项研究中，我们研究了旱地土壤剖面（300 厘米深）中 anammox 和 n-damo 细菌的时空分布。使用同位素示踪技术监测一年过程中的氮（N）转化活性表明，反硝化（冬季 99.0%的 N 损失和夏季 85.0%的 N 损失）优先于 anammox（冬季 1.0%的 N 损失和夏季 14.4%的 N 损失）和 n-damo（冬季 0.6%的 N 损失）在表层土壤（0-20 厘米）中。而在 20 厘米以下的深度，N 损失主要由 anammox 主导（冬季 79.4±14.3%和夏季 65.4±12.5%），且未检测到 n-damo。系统发育分析表明，Candidatus Brocadia anammoxidans 主导了表层土壤中的 anammox 群落，而 Candidatus Brocadia fulgida 则主导了 20 厘米以下的深度。与反硝化相比，发现异化硝酸盐还原为铵（DNRA），另一种亚硝酸盐还原过程，在表层土壤中仅发挥有限的作用（4.9±3.5%）；在 80 厘米以下，DNRA 速率远高于 anammox 和反硝化速率。氨氧化是 80 厘米以上（70.9±23.3%）NO2-的主要来源，是 anammox 速率的关键影响因素，而硝酸盐还原（100%）是 80 厘米以下 NO2-的主要来源。考虑到采样土壤剖面中的 anammox、n-damo 和反硝化速率，反硝化仍然是旱地土壤中主要的 N 损失过程。
