| DOI: | 10.2172/1227715
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| 报告号: | DOE-UTK--SC0006662
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| 报告题名: | PUNCS: Towards Predictive Understanding of Nitrogen Cycling in Soils |
| 作者: | Loeffler, Frank E.; Konstantinidis, Konstantinos T.; Sanford, Robert A.
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| 出版年: | 2015
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| 发表日期: | 2015-11-30
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| 总页数: | 17
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| 国家: | 美国
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| 语种: | 英语
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| 英文关键词: | Nitrogen cycle
; nitrous oxide
; greenhouse gas emissions
; nrfA and nosZ gene diversity and distribution
; monitoring tools
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| 中文主题词: | 土壤
; 碳
; 氮
; 排放物
; 冰上通道
; 硝酸盐
; 亚硝酸盐
; 一氧化二氮/氧化亚氮
; 水道
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| 主题词: | SOILS
; CARBON
; NITROGEN
; EMISSIONS
; LEADS
; NITRATE
; NITRITE
; NITROUS OXIDE
|
| 英文摘要: | In anoxic environments, the major nitrate/nitrite-consuming processes are respiratory ammonification (also known as dissimilatory nitrate reduction to ammonium) and denitrification (i.e., the formation of the gaseous products N2O and N2). Respiratory ammonification oxidizes more carbon per mole of nitrate than denitrification and generates a cation (NH4+), which is retained in soils and bioavailable for plants. Thus, these processes have profoundly different impacts on N retention and greenhouse gas (CO2, N2O) emissions. Microbes capable of respiratory ammonification or denitrification coexist but the environmental controls over these competing nitrate/nitrite-reducing processes are largely unknown. With the current level of understanding, predictions under what environmental conditions respiratory ammonification activity predominates leading to N-retention rather than N-loss are tenuous. Further, the diversity of genes encoding the ammonium-forming nitrite reductase NrfA is poorly defined hampering the development of tools to assess and monitor this activity in environmental systems. Incomplete denitrification leads to N2O, a gas implicated in ozone layer destruction and climate change. The conversion of the greenhouse gas N2O to benign N2 is catalyzed by N2O reductase, the characteristic enzyme system of complete denitrifiers. Thus, efforts to estimate N2O conversion to N2 have focused on the well-characterized denitrifier nosZ genes; however, our understanding of the diversity of genes and organisms contributing to N2O consumption is incomplete. This paucity of information limits the development of more accurate, predictive models for C- and N-fluxes and greenhouse gas emissions. A comprehensive analysis of the key catalyst of respiratory ammonification, ammonia-forming nitrite reductase NrfA, revealed the evolutionary history of nrfA and identified novel diagnostic features, allowing optimized primer design for nrfA monitoring. Further, a novel group of functional âatypicalâ nosZ genes was found indicating that a much broader diversity of genes and organisms contribute to consumption of N2O. The atypical nosZ genes are distributed in soil ecosystems and often outnumber their typical counterparts, emphasizing their potential role in N2O consumption in soils and possibly other environments. Kinetic studies revealed that organisms with atypical NosZ exhibit significantly higher affinity to N2O, indicating that the relative activity of bacteria with typical versus atypical NosZ control N2O emissions and determine a soilâs N2O sink capacity. Collectively, the discoveries made under the PUNCS project improve understanding of N- and associated C-cycling processes in soils, enable the design of enhanced monitoring tools, and allow a larger research community to generate comprehensive datasets required to generate Earth System Models with higher predictive power. |
| URL: | http://www.osti.gov/scitech/servlets/purl/1227715
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| Citation statistics: |
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| 资源类型: | 研究报告
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| 标识符: | http://119.78.100.158/handle/2HF3EXSE/41699
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| Appears in Collections: | 过去全球变化的重建
影响、适应和脆弱性
科学计划与规划
气候变化与战略
全球变化的国际研究计划
气候减缓与适应
气候变化事实与影响
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| 1227715.pdf（392KB） | 研究报告 | -- | 开放获取 | | View
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| Recommended Citation: | |
Loeffler, Frank E.,Konstantinidis, Konstantinos T.,Sanford, Robert A.. PUNCS: Towards Predictive Understanding of Nitrogen Cycling in Soils. 2015-01-01.
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