Marine plastisphere expands the ecological niche and evolutionary dynamics of nrfA-dependent nitrite ammonifying bacteria.

DNRA: A short-circuit in biological N-cycling to conserve nitrogen in terrestrial ecosystems

Straw return and low N addition modify the partitioning of dissimilatory nitrate reduction by increasing conversion to ammonium in paddy fields

Survey of dissimilatory nitrate reduction to ammonium microbial community at national wetland of Shanghai, China

PDF HTML阅读 XML下载 导出引用 引用提醒 硝态氮异化还原机制及其主导因素研究进展 DOI: 10.5846/stxb201407181464 作者: 作者单位: 中国科学院水库水环境重点实验室，中国科学院重庆绿色智能技术研究院，西南大学地理科学学院,中国科学院水库水环境重点实验室，中国科学院重庆绿色智能技术研究院,中国科学院水利部成都山地灾害与环境研究所中国科学院山地表生过程与生态调控重点实验室,西南大学地理科学学院,南京师范大学地理科学学院,中国科学院水库水环境重点实验室，中国科学院重庆绿色智能技术研究院,中国科学院水库水环境重点实验室，中国科学院重庆绿色智能技术研究院 作者简介: 通讯作者: 中图分类号: 基金项目: 中国科学院西部行动计划项目(KZCX2-XB3-14); 重庆市基础与前沿研究项目(cstc2013jcyjA0302);中国科学院水库水环境重点实验室开放基金(RAE2014BA06B) The synergetic and competitive mechanism andthe dominant factors of dissimilatory nitrate reduction processes: a review Author: Affiliation: Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Science;School of Geography Science, Southwest University,,Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Science,Institute of Mountain Hazards and Environment, Chinese Academy of Sciences and Ministry of Water Resources;Key Laboratory of Mountain Environment Evolvement and Regulation,Chinese Academy of Sciences,School of Geography Science, Southwest University,College of Geography Science, Nanjing Normal University,Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Science,Key Laboratory of Reservoir Aquatic Environment, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Science Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:硝态氮(NO3-)异化还原过程通常包含反硝化和异化还原为铵(DNRA)两个方面,是土壤氮素转化的重要途径,其强度大小直接影响着硝态氮的利用和环境效应(如淋溶和氮氧化物气体排放)。反硝化和DNRA过程在反应条件、产物和影响因素等方面常会呈现出协同与竞争的交互作用机制。综述了反硝化和DNRA过程的研究进展及其二者协同竞争的作用机理,并阐述了在NO3-、pH、有效C、氧化还原电位(Eh)等环境条件和土壤微生物对其发生强度和产物的影响,提出了今后应在产生机理、土壤环境因素、微生物学过程以及与其他氮素转化过程耦联作用等方面亟需深入研究,以期增进对氮素循环过程的认识以及为加强氮素管理利用提供依据。 Abstract:The nitrate ion (NO3-), an important form of inorganic soil nitrogen, is susceptible to reduction under anaerobic conditions, and its reduction consists of both assimilatory and dissimilatory processes. The dissimilatory nitrate reduction process-of great significance in nitrogen transformation-includes denitrification and dissimilatory nitrate reduction to ammonium (DNRA). Such reduction processes can directly affect the transformation of nitrates and the environmental consequences (such as NO3- leaching and N2O emission). During the processes of denitrification and DNRA, NO3- is utilized as a substrate, while N2O is generated synchronously. Nonetheless, there are significant differences between denitrification and DNRA, such as metabolic processes, the transformation mechanism, reductases, and the final products. For DNRA, the final product is ammonium (NH4+), which can continue to participate in other soil nitrogen transformation processes, such as crop uptake and nitrification. In agroecosystems, DNRA can consume 3.9%-25.4% of NO3-; this process can decrease NO3- leaching and N2O emissions in comparison with denitrification.Both reducing pathways show a synergistic and competitive mechanism among the reaction conditions, products, and dominant regulators. The synergistic mechanism of denitrification and DNRA manifests itself as the similar suitable environmental conditions, the shared nitrate reductase (Nar), and an intermediate product (N2O), along with the similar soil parameters. Thus, according to the synergistic effect, the dissimilatory nitrate reduction process can be greatly enhanced without limiting factors such as the soil water regimen, temperature, and soil substrates. As for the competitive mechanism, it mainly involves competition for a substrate and energy supplies between denitrification and DNRA. In contrast, the direct competition for NO3- exists ubiquitouslybetween denitrification and DNRA. Nevertheless, regulation of soil parameters (such as available carbon,oxidation-reduction potential (Eh)) changes the concentration of NO3- accordingly; thus, the competition for NO3- between denitrification and DNRA should be rebalanced subsequently. Moreover, soil microorganisms that are related to denitrification and DNRA can compete for a carbon source for their growth and proliferation. The dissimilatory nitrate reduction process is influenced by a great number of factors, mainly environmental conditions and microorganisms. Sufficient soil NO3- and available carbon can significantly enhance the dissimilatory nitrate reduction process, whereas soil pH and Eh have their own suitable ranges for different dissimilatory nitrate reduction processes. The competition between denitrification and DNRA is regulated by these factors. With the changes in available carbon, soil pH, and Eh, the two pathways show different levels of activity. Bacteria can exist in the form of an advantageous microbial population during the dissimilatory nitrate reduction process. Nevertheless, different populations and genes are involved in denitrification and DNRA, and the diversity of soilmicroorganisms is in turn influenced by soil environmental factors. This review summarizes the synergistic and competitive mechanisms and the factors influencing denitrification and DNRA, for example, soil environmental conditions (soil NO3-, soil pH, available carbon and Eh) and microorganisms (population, diversity and genes). The mechanism of formation, soil environmental factors, microbiological processes, and the correlation with other nitrogen transformation processesurgently need further research on dissimilatory nitrate reduction processes. In DNRA, the mechanism of formation and analysis of N2O emissions, populations, diversity, and genes of a microorganism have not been established yet. In addition, the interactions of nitrogen transformation processes in soils-e.g., between denitrification and DNRA or between anaerobic ammonium oxidation and denitrification-should be investigated holistically. The knowledge about synergistic and competitive mechanisms and the factors influencing denitrification and DNRA should improve the understanding of the regulation of nitrogen transformation in soils; this knowledge is also necessary for the development of effective countermeasures and policies on soil nitrogen management. 参考文献 相似文献 引证文献

High nitrogen (N) input in intensive cropping systems has resulted in significant nitrate (NO₃⁻) accumulation in agricultural soils of China. However, despite substantial N input (500-600 kg ha-1 y-1) in the Taihu Lake region, NO₃⁻ accumulation in soils and groundwater therein remains minimal with the mechanisms behind are unclear. Here, we investigated the spatiotemporal distribution and activity of dissimilatory nitrate reduction to ammonium (DNRA), anaerobic ammonium oxidation (anammox), and denitrification, and the associated microbial communities—in the vadose zones of rice-wheat, vegetable, and orchard fields of the Taihu Lake region. Results revealed NO₃⁻ content decreased progressively with soil depth, while NH₄⁺ levels increased, particularly in deeper soil layers. DNRA emerged as the primary pathway for NO₃⁻ reduction, contributing to over 50% of NO₃⁻ removal, especially in the 50–190 cm depth range. Seasonal variations indicated that DNRA activity was highest during spring and autumn, with lower rates observed in winter and summer. DNRA significantly contributed to NH₄⁺ accumulation, with rates strongly positively correlated with NH₄⁺ content, especially in rice-wheat rotation fields characterized by high OC/ NO₃⁻ ratios. Interestingly, DNRA rates were significantly negatively correlated with groundwater N₂O concentrations and the N₂O/(N₂ + N₂O) ratios. Microbial community analysis revealed that the nrfA gene, a marker for DNRA, exhibited higher diversity compared to genes related to denitrification. Additionally, the abundance of DNRA-specialist microbes was positively associated with DNRA rates, particularly in deep layer soils, emphasizing the role of microbial community composition in shaping DNRA activity. These findings demonstrate that DNRA plays a crucial role in facilitating NH₄⁺ accumulation, attenuating NO₃⁻ accumulation, and mitigating N₂O emission in the vadose zone of agricultural croplands in the Taihu Lake region.

Dissimilatory nitrate reduction to ammonium (DNRA) in traditional municipal wastewater treatment plants in China: Widespread but low contribution

Dissimilatory nitrate reduction to ammonium (DNRA) is an important nitrate reduction pathway in freshwater sediments. Many studies have focused on the DNRA process in various natural habitats. However, the joint operation of cascade reservoirs will affect the physical and chemical properties of sediments, which may change the DNRA process and bacterial community pattern in the surface sediments of cascade reservoirs. Our study was the first to investigate the spatiotemporal distribution patterns of potential DNRA rate, nrfA gene abundances, and DNRA bacterial community diversity in surface sediments of the Lancang River cascade reservoirs. The results of slurry incubation experiments combined with the 15N isotope tracer experiment ascertained that the potential rates of DNRA were 0.01-0.15 nmol-N cm-3 h-1, and qPCR results indicated that the abundance range of nrfA was 1.08 × 105-2.51 × 106 copies g-1 dry weight. High throughput sequencing of the nrfA gene revealed that the relative abundance of Anaeromyxobacter (4.52% on average), Polyangium (4.09%), Archangium (1.86%), Geobacter (1.34%), and Lacunisphaera (1.32%) were high. Pearson and RDA correlation analysis exhibited that nrfA gene abundance was positively correlated with altitude, pH, OC, and sand concentration. Anaeromyxobacter was positively correlated with reservoir age and DNRA potential rate. The deterministic environmental selection process plays a crucial role in the formation of the DNRA bacterial community. Network analysis displayed that the dominant DNRA genus was the key population of the DNRA microbial community in the sediments of Lancang River cascade reservoirs. This study reveals that the variation of DNRA bacterial activity and community structure is largely driven by the construction of cascade reservoirs, and provides a new idea for further understanding the characteristics of the DNRA community in the cascade reservoir ecosystem.

Dissimilatory nitrate reduction to ammonium (DNRA) and denitrification are two nitrate respiration pathways in the microbial nitrogen cycle. Diversity and abundance of denitrifying bacteria have been extensively examined in various ecosystems. However, studies on DNRA bacterial diversity are limited, and the linkage between the structure and activity of DNRA communities has yet to be discovered. We examined the composition, diversity, abundance, and activities of DNRA communities at five sites along a salinity gradient in the New River Estuary, North Carolina, USA, a shallow temporal/lagoonal estuarine system. Sediment slurry incubation experiments with 15N-nitrate were conducted to measure potential DNRA rates, while the abundance of DNRA communities was calculated using quantitative PCR of nrfA genes encoding cytochrome C nitrite reductase, commonly found in DNRA bacteria. A pyrosequencing method targeting nrfA genes was developed using an Ion Torrent sequencer to examine the diversity and composition of DNRA communities within the estuarine sediment community. We found higher levels of nrfA gene abundance and DNRA activities in sediments with higher percent organic content. Pyrosequencing analysis of nrfA genes revealed spatial variation of DNRA communities along the salinity gradient of the New River Estuary. Percent abundance of dominant populations was found to have significant influence on overall activities of DNRA communities. Abundance of dominant DNRA bacteria and organic carbon availability are important regulators of DNRA activities in the eutrophic New River Estuary.

Dissimilatory nitrate reduction to ammonium (DNRA) plays an important role in keeping nitrate retention as a more bioavailable form (ammonium) in estuarine and intertidal environments. However, the effects of soil abiotic and biotic characteristics on DNRA in Spartina alterniflora ecotones of estuarine and intertidal wetlands remain unclear. In this study, we used nitrogen isotope tracing and molecular approaches to investigate DNRA activity, and abiotic and biotic factors of both rhizosphere and non-rhizosphere soils in Spartina alterniflora ecotones of the Yangtze estuarine and intertidal wetlands. DNRA varied significantly throughout the sampling sites, with potential rates of 0.53–3.57 nmol N g−1 h−1. The rates of DNRA were significantly higher in rhizosphere than non-rhizosphere soils at the oligohaline sites. Salinity had more influence on DNRA activity than Spartina alterniflora at the brackish sites. Total organic carbon, nitrate, Fe (II) and sulfide were significantly correlated with DNRA rates and nrfA gene abundance. Soil substrates strongly affected DNRA activity in rhizosphere soil, while nrfA gene abundance was the predominant factor mediating DNRA activity in non-rhizosphere soil. DNRA contributed more to the total nitrate reduction at the brackish than oligohaline sites, suggesting that DNRA plays an important role in nitrate reduction in estuarine and intertidal wetlands. This study suggests that soil substrates rather than nrfA gene dominate DNRA activity in estuarine and intertidal wetlands after Spartina alterniflora invasion. Our results are helpful to understand the importance of soil characteristics changes induced by the exotic plant invasion to nitrogen cycling in estuarine and intertidal wetlands.

Functional microbial inoculants affect the balance of DNRA and denitrification pathways in compost amended soil.

Dissimilatory nitrate reduction to ammonium (DNRA) potentially facilitates the accumulation of phosphorus in lake water from sediment.

Dissimilatory nitrate reduction to ammonia (DNRA) is the process in which nitrate is reduced, via nitrite, to ammonia. Bacteria known to carry out DNRA mainly originate from wastewater treatment plants, where DNRA is a relevant process. The ability to carry out DNRA is phylogenetically widespread, and the gene nrfA, encoding for the key enzyme of the second step of the pathway, could be used as a marker for this process. In this study we developed a new primer pair specific for nrfA in the genus Desulfovibrio. The specificity of the primer pair was tested on DNA from thirteen species of Desulfovibrio and DNA from two wastewater samples. PCR amplifications yielded products of the expected size (850 bp), and sequences obtained from Desulfovibrio strains and environmental sample clone libraries matched the Desulfovibrio nrfA gene. Nevertheless, we found nrfA gene sequences in the environmental samples that are not present in the databases. The new primer set can be used to obtain more sequences of the nrfA gene and improve our knowledge of the DNRA pathway in this genus, e.g. with the aim to improve the wastewater treatment process.

Role of organic carbon, nitrate and ferrous iron on the partitioning between denitrification and DNRA in constructed stormwater urban wetlands

Dissimilatory nitrate reduction to ammonium (DNRA): A unique biogeochemical cycle to improve nitrogen (N) use efficiency and reduce N-loss in rice paddy

Dissimilatory nitrate reduction to ammonium (DNRA), denitrification, anaerobic ammonium oxidation (anammox), and biological N2 fixation (BNF) can influence the nitrogen (N) use efficiency of rice production. While the effect of N application on BNF is known, little is known about its effect on NO3- partitioning between DNRA, denitrification, and anammox. Here, we investigated the effect of N application on DNRA, denitrification, anammox, and BNF and on the abundance of relevant genes in three paddy soils in Australia. Rice was grown in a glasshouse with N fertilizer (150 kg N ha-1) and without N fertilizer for 75 days, and the rhizosphere and bulk soils were collected separately for laboratory incubation and quantitative PCR analysis. Nitrogen application reduced DNRA rates by >16% in all the soils regardless of the rhizospheric zone, but it did not affect the nrfA gene abundance. Without N, the amount and proportion of NO3- reduced by DNRA (0.42 to 0.52 μg g-1 soil day-1 and 45 to 55%, respectively) were similar to or higher than the amount and proportion reduced by denitrification. However, with N the amount of NO3- reduced by DNRA (0.32 to 0.40 μg g-1 soil day-1) was 40 to 50% lower than the amount of NO3- reduced by denitrification. Denitrification loss increased by >20% with N addition and was affected by the rhizospheric zones. Nitrogen loss was minimal through anammox, while BNF added 0.02 to 0.25 μg N g-1 soil day-1 We found that DNRA plays a significant positive role in paddy soil N retention, as it accounts for up to 55% of the total NO3- reduction, but this is reduced by N application.IMPORTANCE This study provides evidence that nitrogen addition reduces nitrogen retention through DNRA and increases nitrogen loss via denitrification in a paddy soil ecosystem. DNRA is one of the major NO3- reduction processes, and it can outcompete denitrification in NO3- consumption when rice paddies are low in nitrogen. A significant level of DNRA activity in paddy soils indicates that DNRA plays an important role in retaining nitrogen by reducing NO3- availability for denitrification and leaching. Our study shows that by reducing N addition to rice paddies, there is a positive effect from reduced nitrogen loss but, more importantly, from the conversion of NO3- to NH4+, which is the favored form of mineral nitrogen for plant uptake.