Denitrification dominates dissimilatory nitrate reduction across global natural ecosystems.

Denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) are three competing processes of microbial nitrate reduction that determine the degree of ecosystem nitrogen (N) loss versus recycling. However, the global patterns and drivers of relative contributions of these N cycling processes to soil or sediment nitrate reduction remain unknown, limiting our understanding of the global N balance and management. Here, we compiled a global dataset of 1570 observations from a wide range of terrestrial and aquatic ecosystems.

Type VI secretion system drives bacterial diversity and functions in multispecies biofilms.

Type VI secretion system (T6SS) plays an essential role in interspecies interactions and provides an advantage for a strain with T6SS in multispecies biofilms. However, how T6SS drives the bacterial community structure and functions in multispecies biofilms still needs to be determined. Using gene deletion and Illumina sequencing technique, we estimated bacterial community responses in multispecies biofilms to T6SS by introducing T6SS-containing Pseudomonas putida KT2440.

Temperature drives elevational diversity patterns of different types of organisms in Qinghai-Tibetan Plateau wetlands.

The spatial pattern and driving mechanism of biodiversity along elevational gradients are key topics in ecology. However, it is still unclear whether the multidimensional diversity of different types of organisms shows a similar response to elevation changes. Here, we measured the species and phylogenetic diversity of plants, bacteria, fungi, and microbial functional groups (nitrifiers, denitrifiers, methanogens, and methanotrophs) in 36 wetland sites on the Qinghai-Tibetan Plateau.

Feammox is more important than anammox in anaerobic ammonium loss in farmland soils around Lake Taihu, China.

Ammonium (NH) oxidation is a key step in nitrogen transformation in ecosystems. Prior to the recent discovery of Feammox (anaerobic NH oxidation coupled with iron reduction), anammox (anaerobic NH oxidation coupled with nitrite reduction) was thought of as the only pathway by which anaerobic NH loss (NH directly to N) occurs in soils. Experimental evidence has confirmed that both anammox and Feammox contribute to anaerobic NH loss; however, their relative contributions to this process in farmland soils are largely unknown.

Evidence for the occurrence of Feammox coupled with nitrate-dependent Fe(II) oxidation in natural enrichment cultures.

Feammox is a newly discovered process of anaerobic ammonium oxidation driven by Fe(III) reduction. Nitrate-dependent Fe(II) oxidation (NDFO) is the coupling of Fe(II) oxidation and nitrate reduction to produce N under anaerobic conditions. It has not been reported whether the coupling of the two reactions exists in natural enrichment.

Nitrogen loss through denitrification, anammox and Feammox in a paddy soil.

Since the process of anaerobic ammonium oxidation (anammox) coupled with ferric iron reduction (termed Feammox) was discovered, it has been observed in various natural environments. However, besides the vertical distribution of Feammox in paddy soils, its differences and relationships with traditional nitrogen loss processes, including denitrification and anammox, remain unclear. Here, we studied the distribution of nitrogen loss pathways in different layers (0-50 cm) of paddy soil in southeastern China using N isotope tracer technology and molecular analysis.

Effects of the addition of nitrogen and phosphorus on anaerobic ammonium oxidation coupled with iron reduction (Feammox) in the farmland soils.

Anaerobic ammonium oxidation coupled with iron reduction is termed as Feammox, and is a new nitrogen removal process. However, there is a paucity of studies on the response of nutrient additions on Feammox process in farmland ecosystems. In this study, we investigated the shifts of Feammox and iron-reducers under nitrogen (N) and phosphorus (P) applications via isotopic tracing and high-throughput sequencing technology.

Impact of sand mining on the carbon sequestration and nitrogen removal ability of soil in the riparian area of Lijiang River, China.

Riparian areas are widely recognized as the main areas for carbon sequestration and nitrogen pollution removal, while little is known about the effects of the respective sand mining activities on riparian zones. In this study, the effects of sand mining activities on the soil organic carbon (SOC) storage, different N-removal processes (Feammox, anammox, and denitrification), and composition of the relative bacterial community at a depth of 0-40 cm were determined based on investigations in riparian sand mining areas and adjacent forestlands. The SOC density of the sand mining areas (2.

[Denitrification and Anaerobic Ammonium Oxidation in Soil Nitrogen Migration Process in a Farmland of Wanshandang Lake].

To explore the rate variation and contribution to N loss of denitrification and anaerobic ammonia oxidation (ANAMMOX) in the nitrogen migration process of farmland soils in southern China, we assess the physicochemical characteristics soil samples of different soil layers from farmland and different land use types (farmland, river channel, riparian zone, and lake sediment) in a wheat-rice rotation area of Wanshandang Lake. Illumina MiSeq sequencing and quantitative real-time polymerase chain reaction (qPCR) are used to investigate the microbial community composition and functional gene abundances of the samples. The potential denitrification and ANAMMOX rate (calculated by N) of each sample was determined by an isotope culture experiment.

[Insight into the Process of Mn-ANAMMOX in Soils of Agricultural Drainage Ditches].

Anaerobic ammonium oxidation mediated by MnO (termed Mn-ANAMMOX) is a newly discovered microbial nitrogen removal pathway. However, few studies have reported on the Mn-ANAMMOX process and related microbial communities in agricultural drainage ditches. In this study, Mn(Ⅳ)-reducing bacteria (MnBR) enrichment cultivation was carried out for 340 days and an isotope tracing technique and high-throughput sequencing technology were used to provide convincing evidence of the occurrence of Mn-ANAMMOX.

Nitrogen loss through anaerobic ammonium oxidation mediated by Mn(IV)-oxide reduction from agricultural drainage ditches into Jiuli River, Taihu Lake Basin.

Up to date, no great breakthrough has been made in the research of anaerobic ammonium oxidation mediated by Mn(IV)-oxide reduction (termed Mnammox). Recently, the Feammox process has become a hot research topic in the study of nitrogen loss from soils. Interestingly, in this study, an alternative pathway of N loss was proposed in terrestrial ecosystems.

Spatial and seasonal distributions of Feammox from ecosystem habitats in the Wanshan region of the Taihu watershed, China.

Anaerobic ammonium oxidation coupled to Fe(III) reduction, termed Feammox, is a newly identified microbial process that occurs in nitrogen and iron cycles. As the seasonal distribution of Feammox in different ecosystem habitats has not been fully explored, this study investigated the potential Feammox rates and the diversity and abundance of iron reducing bacteria (IRB) in three habitats during two seasons by using isotope tracing technique and molecular analysis, respectively. Results showed that potential Feammox rates vary both seasonally and spatially, having relatively higher rates in summer (0.

Variation of Feammox following ammonium fertilizer migration in a wheat-rice rotation area, Taihu Lake, China.

Feammox is a newly discovered and important anaerobic nitrogen (N) loss pathway, and its variation and role in removing N following the application of N fertilizer and its migration from paddies to other land use types and from surface soils to deep soils have not been thoroughly elucidated to date. In this study, field sampling and slurry incubation experiments were performed to evaluate the Feammox rate between different land use types (paddy, irrigation ditch, riparian zone and lake, 0-10 cm) and different paddy soil depths (0-70 cm) in a wheat-rice rotation area in China. Based on a N-labelled isotope-tracing technique and analysis of microbial communities, it was estimated that the potential Feammox rate ranged from 0.

Nitrogen loss through anaerobic ammonium oxidation coupled to Iron reduction from ecosystem habitats in the Taihu estuary region.

Anaerobic ammonium oxidation coupled to iron reduction, termed Feammox, is a new microbial process linked the nitrogen cycles. However, the nitrogen losses through Feammox from different ecosystem habitats remain unclear. In this study, isotope tracing technology and molecular microbial analysis were used to investigate the Feammox and its contribution to the nitrogen loss in the farmland and riparian soils, and river sediments.

[Effect of -Immobilized Nitrogen Cycling Bacteria on the Mechanism of Nitrogen Removal in Polluted River Water].

Surface water, and undisturbed sediment cores from the Qinshui River in Gonghu Bay were collected to carry out a simulation experiment in a laboratory to study the effect of -immobilized nitrogen-cycling bacteria on nitrogen removal mechanisms from the river water. In this study, the transformation and fate of ammonium among four different treatment groups were investigated by using a stable N isotope pairing technique combined with high-throughput sequencing technology[Treatment A:bare sediment, Treatment B:sediment+immobilized nitrogen cycling bacteria (INCB), Treatment C:sediment+, Treatment D:sediment+INCB+]. The results of the N mass-balance model showed that there were three pathways to the ultimate fate of nitrogen:precipitated with the sediments, absorbed by and consumed by microbial processes[denitrification and anaerobic ammonium oxidation (ANAMMOX)].

[Insight into the Mechanism of Feammox in the Surface Soils of a Riparian Zone].

Anaerobic ammonium oxidation coupled to iron (Ⅲ) reduction (termed Feammox) is a recently discovered pathway of nitrogen cycling. However, little is known about the pathways of N transformation via the Feammox process in riparian zones. In this study, evidence of Feammox in the riparian zone soil layers (0-20 cm) was demonstrated using the isotope tracing technique and a high-throughput sequencing technology.

Nitrogen loss from anaerobic ammonium oxidation coupled to Iron(III) reduction in a riparian zone.

Anaerobic ammonium oxidation coupled to iron(III) reduction (termed Feammox) is a recently discovered pathway of nitrogen cycling. However, little is known about the pathways of N transformation via Feammox process in riparian zones. In this study, evidence for Feammox in riparian zones with or without vegetation cover was demonstrated using isotope tracing technique and high-throughput sequencing technology.