Xi Dan, Bai Ren, Zhang Limei, Fang Yunting
Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China.
Qingyuan Forest CERN, Shenyang, China.
Appl Environ Microbiol. 2016 Jul 15;82(15):4602-4612. doi: 10.1128/AEM.00888-16. Print 2016 Aug 1.
Anaerobic ammonium oxidation with nitrite reduction to dinitrogen (termed anammox) has been reported to be an important process for removing fixed nitrogen (N) in marine ecosystems and in some agricultural and wetland soils. However, its importance in upland forest soils has never been quantified. In this study, we evaluated the occurrence of anammox activity in two temperate forest soils collected from northeastern China. With (15)N-labeled NO3 (-) incubation, we found that the combined potential of the N2 production rates of anammox and codenitrification ranged from 0.01 ± 0.01 to 1.2 ± 0.18 nmol N per gram of soil per hour, contributing 0.5% to 14.4% of the total N2 production along the soil profile. Denitrification was the main pathway of N2 production and accounted for 85.6% to 99.5% of the total N2 production. Further labeling experiments with (15)NH4 (+) and (15)NO2 (-) indicated that codenitrification was present in the mixed forest soil. Codenitrification and anammox accounted for 2% to 12% and 1% to 7% of the total N2 production, respectively. Two anammox species, "Candidatus Brocadia fulgida" and "Candidatus Jettenia asiatica," were detected in this study but in very low abundance (as indicated by the hzsB gene). Our results demonstrated that the anammox process occurs in forest soils, but the contribution to N2 loss might be low in these ecosystems. More research is necessary to determine the activities of different N2 releasing pathways in different forest soils.
In this study, we examined the anammox activity in temperate upland forest soils using the (15)N isotope technique. We found that the anammox process contributed little to the N2 production rate in the studied forest soil. Two anammox organisms, "Candidatus Brocadia fulgida" and "Candidatus Jettenia asiatica," were detected. In addition, we found that codenitrification was another N2 production pathway in forest soils. Our results could contribute to the understanding of soil gaseous N losses and microbial controls in forest soils.
据报道，亚硝酸还原为氮气的厌氧氨氧化（称为厌氧氨氧化）是海洋生态系统以及一些农业和湿地土壤中去除固定氮（N）的重要过程。然而，其在山地森林土壤中的重要性从未被量化。在本研究中，我们评估了从中国东北采集的两种温带森林土壤中厌氧氨氧化活性的发生情况。通过（15）N标记的NO3（-）培养，我们发现厌氧氨氧化和共反硝化作用产生N2的速率综合潜力为每克土壤每小时0.01±0.01至1.2±0.18 nmol N，占土壤剖面总N2产生量的0.5%至14.4%。反硝化作用是N2产生的主要途径，占总N2产生量的85.6%至99.5%。进一步用（15）NH4（+）和（15）NO2（-）进行标记实验表明，混交林土壤中存在共反硝化作用。共反硝化作用和厌氧氨氧化分别占总N2产生量 的2%至12%和1%至7%。在本研究中检测到两种厌氧氨氧化菌，“Candidatus Brocadia fulgida”和“Candidatus Jettenia asiatica”，但丰度非常低（如hzsB基因所示）。我们的结果表明，厌氧氨氧化过程发生在森林土壤中，但在这些生态系统中对N2损失的贡献可能较低。需要更多研究来确定不同森林土壤中不同N2释放途径的活性。
在本研究中，我们使用（15）N同位素技术检测了温带山地森林土壤中的厌氧氨氧化活性。我们发现，厌氧氨氧化过程对所研究森林土壤中N2产生速率的贡献很小。检测到两种厌氧氨氧化生物，“Candidatus Brocadia fulgida”和“Candidatus Jettenia asiatica”。此外，我们发现共反硝化作用是森林土壤中另一种N2产生途径。我们的结果有助于理解森林土壤中气态氮损失和微生物控制。
