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1.
Ellen Kandeler Thomas Brune Esther Enowashu Nicole Dörr Georg Guggenberger Norbert Lamersdorf & Laurent Philippot 《FEMS microbiology ecology》2009,67(3):444-454
A field-scale manipulation experiment conducted for 16 years in a Norway spruce forest at Solling, Central Germany, was used to follow the long-term response of total soil bacteria, nitrate reducers and denitrifiers under conditions of reduced N deposition. N was experimentally removed from throughfall by a roof construction ('clean rain plot'). We used substrate-induced respiration (SIR) to characterize the active fraction of soil microbial biomass and potential nitrate reduction to quantify the activity of nitrate reducers. The abundance of total bacteria, nitrate reducers and denitrifiers in different soil layers was analysed by quantitative PCR of 16S rRNA gene, nitrate reduction and denitrification genes. Reduced N deposition temporarily affected the active fraction of the total microbial community (SIR) as well as nitrate reductase activity. However, the size of the total, nitrate reducer and denitrifier communities did not respond to reduced N deposition. Soil depth and sampling date had a greater influence on the density and activity of soil microorganisms than reduced deposition. An increase in the nosZ /16S rRNA gene and nosZ/nirK ratios with soil depth suggests that the proportion of denitrifiers capable of reducing N2 O into N2 is larger in the mineral soil layer than in the organic layer. 相似文献
2.
LYDIE CHAPUIS-LARDY NICOLE WRAGE† AURÉLIE METAY‡ JEAN-LUC CHOTTE§ MARTIAL BERNOUX§ 《Global Change Biology》2007,13(1):1-17
Soils are the main sources of the greenhouse gas nitrous oxide (N2 O). The N2 O emission at the soil surface is the result of production and consumption processes. So far, research has concentrated on net N2 O production. However, in the literature, there are numerous reports of net negative fluxes of N2 O, (i.e. fluxes from the atmosphere to the soil). Such fluxes are frequent and substantial and cannot simply be dismissed as experimental noise.
Net N2 O consumption has been measured under various conditions from the tropics to temperate areas, in natural and agricultural systems. Low mineral N and large moisture contents have sometimes been found to favour N2 O consumption. This fits in with denitrification as the responsible process, reducing N2 O to N2 . However, it has also been reported that nitrifiers consume N2 O in nitrifier denitrification. A contribution of various processes could explain the wide range of conditions found to allow N2 O consumption, ranging from low to high temperatures, wet to dry soils, and fertilized to unfertilized plots. Generally, conditions interfering with N2 O diffusion in the soil seem to enhance N2 O consumption. However, the factors regulating N2 O consumption are not yet well understood and merit further study.
Frequent literature reports of net N2 O consumption suggest that a soil sink could help account for the current imbalance in estimated global budgets of N2 O. Therefore, a systematic investigation into N2 O consumption is necessary. This should concentrate on the organisms, reactions, and environmental factors involved. 相似文献
Net N
Frequent literature reports of net N
3.
Abstract Denitrification rates were measured as N2 O production in two water-logged forest soils at monthly intervals. The effect of acetylene inhibition and the addition of nitrate, glucose, acetate and celloboise in field incubations was examined.
N2 O release from the two soils was very low, 26 mg N2 m−2 y−1 in ash and 178 mg N2 in alder. In acetylene inhibited incubations N2 O production was higher, 296 and 486 mg N2 m−2 y−1 in ash and alder respectively. After addition of nitrate and C-sources to a 10 mM concentration, denitrification rates increased to 5–15 times higher values.
The denitrification rates below 4°C were low and most N2 O was produced in late spring and summer.
The highest rate of denitrification during a 50 h incubation experiment occurred between 3 and 23 h. 相似文献
N
The denitrification rates below 4°C were low and most N
The highest rate of denitrification during a 50 h incubation experiment occurred between 3 and 23 h. 相似文献
4.
Metabolism of nitric oxide and nitrous oxide during nitrification and denitrification in soil at different incubation conditions 总被引:1,自引:0,他引:1
Abstract NO production and consumption rates as well as N2 O accumulation rates were measured in a loamy cambisol which was incubated under different conditions (i.e. soil moisture content, addition of nitrogen fertilizer and/or glucose, aerobic or anaerobic gas phase). Inhibition of nitrification with acetylene allowed us to distinguish between nitrification and denitrification as sources of NO and N2 O. Under aerobic conditions untreated soil showed very low release of NO and N2 O but high consumption of NO. Fertilization with NH4 + or urea stimulated both NO and N2 O production by nitrification. Addition of glucose at high soil moisture contents led to increased N2 and N2 O production by denitrification, but not to increased NO production rates. Anaerobic conditions, however, stimulated both NO and N2 O production by denitrification. The production of NO and N2 O was further stimulated at low moisture contents and after addition of glucose or NO3 − . Anaerobic consumption of NO by denitrification followed Michaelis-Menten kinetics and was stimulated by addition of glucose and NO3 − . Aerobic consumption of NO followed first-order kinetics up to mixing ratios of at least 14 ppmv NO, was inhibited by autoclaving but not by acetylene, and decreased with increasing soil moisture content. The high NO-consumption activity and the effects of soil moisture on the apparent rates of anaerobic and aerobic production and consumption of NO suggest that diffusional constraints have an important influence on the release of NO, and may be a reason for the different behaviour of NO release vs N2 O release. 相似文献
5.
Spatially tripartite interactions of denitrifiers in arctic ecosystems: activities, functional groups and soil resources 总被引:1,自引:0,他引:1
Soil denitrification is one of the most significant contributors to global nitrous oxide (N(2) O) emissions, and spatial patterns of denitrifying communities and their functions may reveal the factors that drive denitrification potential and functional consortia. Although denitrifier spatial patterns have been studied extensively in most soil ecosystems, little is known about these processes in arctic soils. This study aimed to unravel the spatial relationships among denitrifier abundance, denitrification potential and soil resources in 279 soil samples collected from three Canadian arctic ecosystems encompassing 7° in latitude and 27° in longitude. The abundance of nirS (10(6) -10(8) copies?g(-1) dry soil), nirK (10(3) -10(7) copies?g(-1) dry soil) and nosZ (10(6) -10(7) copies?g(-1) dry soil) genes in these soils is in the similar range as non-arctic soil ecosystems. Potential denitrification in Organic Cryosols (1034?ng?N(2) O-N?g(-1) soil) was 5-11 times higher than Static/Turbic Cryosols and the overall denitrification potential in Cryosols was also comparable to other ecosystems. We found denitrifier functional groups and potential denitrification were highly spatially dependent within a scale of 5?m. Functional groups and soil resources were significantly (P?0.01) correlated to potential denitrifier activities and the correlations were stronger in Organic Cryosols. Soil moisture, organic carbon and nitrogen content were the predominant controls with nirK abundance also linked to potential denitrification. This study suggests that the dominant control on arctic ecosystem-level denitrification potential is moisture and organic carbon. Further, microbial abundance controls on ecosystem level activity while undoubtedly present, are masked in the nutrient-poor arctic environment by soil resource control on denitrifier ecosystem level activity. 相似文献
6.
Metabolism of nitric oxide and nitrous oxide during nitrification and denitrification in soil at different incubation conditions 总被引:4,自引:0,他引:4
Abstract NO production and consumption rates as well as N2 O accumulation rates were measured in a loamy cambisol which was incubated under different conditions (i.e. soil moisture content, addition of nitrogen fertilizer and/or glucose, aerobic or anaerobic gas phase). Inhibition of nitrification with acetylene allowed us to distinguish between nitrification and denitrification as sources of NO and N2 O. Under aerobic conditions untreated soil showed very low release of NO and N2 O but high consumption of NO. Fertilization with NH4 + or urea stimulated both NO and N2 O production by nitrification. Addition of glucose at high soil moisture contents led to increased N2 and N2 O production by denitrification, but not to increased NO production rates. Anaerobic conditions, however, stimulated both NO and N2 O production by denitrification. The production of NO and N2 O was further stimulated at low moisture contents and after addition of glucose or NO3 − . Anaerobic consumption of NO by denitrification followed Michaelis-Menten kinetics and was stimulated by addition of glucose and NO3 − . Aerobic consumption of NO followed first-order kinetics up to mixing ratios of at least 14 ppmv NO, was inhibited by autoclaving but not by acetylene, and decreased with increasing soil moisture content. The high NO-consumption activity and the effects of soil moisture on the apparent rates of anaerobic and aerobic production and consumption of NO suggest that diffusional constraints have an important influence on the release of NO, and may be a reason for the different behaviour of NO release vs N2 O release. 相似文献
7.
Denitrification in river sediments: relationship between process rate and properties of water and sediment 总被引:6,自引:0,他引:6
1. A survey was made of denitrification and nitrous oxide (N2 O) production in river sediments at fifty sites in north‐east England during one season in order to investigate the relationship between rates and environmental factors likely to influence these processes. The sites were chosen to represent a wide range of physical and chemical conditions. Denitrification rate and N2 O production were measured within 5 h of sampling using the slurry acetylene blockage technique.
2. Denitrification rate ranged from less than 0.005–260 nmol N g–1 DW h–1 , tending to increase in a downstream direction. N2 O production ranged from negative values (net consumption) to 13 nmol N2 O‐N g–1 DW h–1 and accounted for 0–115% of the N gases produced.
3. Denitrification rate and N2 O concentration in the sediment were correlated positively with nitrate concentration in the water column, water content of the sediment and percentage of fine (< 100 μm) particles in the sediment.
4. The variation in denitrification rate was satisfactorily explained (64% total variance) by a model employing measurements of water nitrate and water content of sediments. No simple or multiple relationship was found for N2 O production. 相似文献
2. Denitrification rate ranged from less than 0.005–260 nmol N g
3. Denitrification rate and N
4. The variation in denitrification rate was satisfactorily explained (64% total variance) by a model employing measurements of water nitrate and water content of sediments. No simple or multiple relationship was found for N
8.
Measurement of denitrification in estuarine sediment using membrane inlet mass spectrometry 总被引:1,自引:0,他引:1
Abstract Denitrification was measured in intact sediment cores and in homogenised slurries using membrane inlet mass spectrometry. Dissolved concentrations of O2 , N2 , N2 O and CO2 were simultaneously monitored. Using a 0.8 mm diameter needle probe, a comparison was made of the gas profiles of intact cores obtained under different conditions, i.e. with air or argon as the headspace gas and after the addition of nitrate and/or a carbon source to the sediment surface. O2 was detectable to a depth of 1 cm under a headspace of air and the depth at which the maxima of denitrification products occurred was 1.5–2 cm. Denitrification products (N2 O, N2 ) occurred in the surface layers where O2 was above the minimum level of detectability (> 0.25 μM): diffusion of N2 and N2 O upwards from the anoxic zone, local anaerobic microenvironments or aerobic denitrification are alternative explanations for this observation. The addition of nitrate and/or acetate increased the concentrations of N2 , N2 O and CO2 in the sediment core. In sediment slurries, the pH, nitrate concentration, carbon source and the depth from which the sample was taken affected the rate of denitrification. Nitrogen was the sole detectable end product. Maximum denitrification occurred at pH 7.5 and at 20 mM nitrate. Denitrification was at a maximum in those slurries prepared from sections of core at 1–2 cm depth. 相似文献
9.
Abstract Production of N2 O was detected within 30 min of adding water to very dry soil (matric water potential < −9 MPa) sampled at the end of the dry season from an annual grassland of California, U.S.A. Using C2 H2 to inhibit nitrification, we demonstrate that nitrification was a modest source of N2 O in sieved soil wetted to a water content below field capacity, but that denitrification was the major source of N2 O in sieved soils wetted to a water content above field capacity and in intact cores wetted either below or above field capacity. Significant abiological sources of N2 O were not detected. De novo enzyme synthesis began within 4–8 h of wetting, and denitrifying enzyme activity doubled within 26 h, indicating that denitrifying bacteria can quickly transform their metabolic state from adaptation to severe drought stress to rapid exploitation of changing resources. 相似文献
10.
Abstract: A component of Hamilton Harbour sediment prevented nitrous oxide (N2 O) reduction in denitrification assays with a mixed population of endogenous bacteria and a pure culture (HH1) isolated from the sediment. A 5% (v/v) concentration of sediment in nutrient broth caused near maximum inhibition of N2 O reduction. Sediment taken from a site closer to pollution sources (Site 906) was twice as inhibitory (as measured by N2 O accumulation) as sediment from Site 910, further from pollution sources. N2 O persistence was associated with the particulate sediment fraction only. Several heavy metals were tested at in situ concentrations, and ionic cadmium (Cd) and chromium (Cr) caused N2 O accumulation. Ashed sediment did not cause N2 O accumulation, but did decrease initial nitrate reduction rates with HH1. 相似文献
11.
Abstract Samples of water, sediment and bacterial mat from hot springs in Grændalur and Hveragerdi areas in southwestern Iceland were screened at 70°C and 80°C for thermophilic denitrifying bacteria by culturing in anaerobic media containing nitrate or N2 O as the terminal oxidant. The springs ranged in temperature from 65–100°C and included both neutral (pH 7–8.5) and acidic (pH 2.5–4) types. Nitrate reducing bacteria (nitrate → nitrite) and denitrifiers (nitrate → N2 ) were found that grew at 70°C but not at 80°C in nutrient media at pH 8. Samples from neutral springs that were cultured at pH 8 failed to yield a chemolithotrophic, sulfur-oxidizing and nitrate-reducing bacterium, and samples from acidic springs that were cultured at pH 3.5 seemed entirely to lack dissimilatory, nitrate-utilizing bacteria. No sample yielded an organism capable of growth solely by N2 O respiration. The denitrifiers appeared to be Bacillus . Two such Bacillus strains were examined in pure culture and found to exhibit the unusual denitrification phenotype described previously for the mesophile, Pseudomonas aeruginosa , and one other strain of thermophilic Bacillus . The phenotype is characterized by the ability to grow by reduction of nitrate to N2 with N2 O as an intermediate but a virtual inability to reduce N2 O when N2 O was the sole oxidant. 相似文献
12.
Abstract Samples of water, sediment and bacterial mat from hot springs in Grændalur and Hveragerdi areas in southwestern Iceland were screened at 70°C and 80°C for thermophilic denitrifying bacteria by culturing in anaerobic media containing nitrate or N2 O as the terminal oxidant. The s springs ranged in temperature from 65–100°C and included both neutral (pH 7–8.5) and acidic (pH 2.5–4) types. Nitrate reducing bacteria (nitrate → nitrite) and denitrifiers (nitrate → N2 ) were found that grew at 70°C but not at 80°C in nutrient media at pH 8. Samples from neutral springs that were cultured at pH 8 failed to yield a chemolithotrophic, sulfur-oxidizing and nitrate-reducing bacterium, and samples from acidic springs that were cultured at pH 3.5 seemed entirely to lack dissimilatory, nitrate-utilizing bacteria. No sample yielded an organism capable of growth solely by N2 O respiration. The denitrifiers appeared to be Bacillus . Two such Bacillus strains were examined in pure culture and found to exhibit the unusual denitrification phenotype described previously for the mesophile, Pseudomonas aeruginosa , and one other strain of thermophilic Bacillus . The phenotype is characterized by the ability to grow by reduction of nitrate to N2 with N2 O as an intermediate but a virtual inability to reduce N2 O when N2 O was the sole oxidant. 相似文献
13.
JANET E. BERTRAM TIM J. CLOUGH ROBERT R. SHERLOCK LEO M. CONDRON MAUREEN O'CALLAGHAN† NAOMI S. WELLS JESSICA L. RAY 《Global Change Biology》2009,15(8):2067-2077
Atmospheric concentrations of the greenhouse gas nitrous oxide (N2 O) have continued to rise since the advent of the industrial era, largely because of the increase in agricultural land use. The urine deposited by grazing ruminant animals is a major global source of agricultural N2 O. With the first commitment period for reducing greenhouse gas emissions under the Kyoto Protocol now underway, mitigation options for ruminant urine N2 O emissions are urgently needed. Recent studies showed that increasing the urinary concentration of the minor urine constituent hippuric acid resulted in reduced emissions of N2 O from a sandy soil treated with synthetic bovine urine, due to a reduction in denitrification. A similar effect was seen when benzoic acid, a product of hippuric acid hydrolysis, was used. This current laboratory experiment aimed to investigate these effects using real cow urine for the first time. Increased concentrations of hippuric acid or benzoic acid in the urine led to reduction of N2 O emissions by 65% (from 17% to <6% N applied), with no difference between the two acid treatments. Ammonia volatilization did not increase significantly with increased hippuric acid or benzoic acid concentrations in the urine applied. Therefore, there was a net reduction in gaseous N loss from the soil with higher urinary concentrations of both hippuric acid and benzoic acid. The results show that elevating hippuric acid in the urine had a marked negative effect on both nitrification and denitrification rates and on subsequent N2 O fluxes. This study indicates the potential for developing a novel mitigation strategy based on manipulation of urine composition through ruminant diet. 相似文献
14.
Denitrification and nitrate-reducing bacterial populations in abandoned and reclaimed minesoils 总被引:1,自引:0,他引:1
Abstract Microbial populations, nitrogen mineralization potentials, and denitrification enzyme activities were examined in two abandoned carbolithic minesoils. Numbers and activities of bacteria and fungi were lower in nonamended than in lime and/or fly ash amended sites. Rates of aerobic NO3 − production (3 to 38 μg-N kg−1 h−1 ) and anaerobic NO3 − reduction to N2 O (5 to 68 μg-N kg−1 h−1 ) were measured. Organisms capable of N2 O production under anaerobic soil conditions were present in low numbers, and their activity was restricted in part by low soil pH. Nondenitrifying nitrate-reducing bacteria were more diverse and in greater numbers than respiratory denitrifiers and may have been responsible for N2 O production in assays measuring denitrification enzyme activity. 相似文献
15.
Abstract A denitrifying Cytophaga was isolated from soil enriched by anaerobic incubation with glucose, sulfide (S2− ), nitrous oxide (N2 O), and acetylene (C2 H2 ). Such soil enrichments and pure cultures of the isolated Cytophaga reduced N2 O rapidly even in the presence of a normally inhibitory concentration of C2 H2 (4 kPa) providing S2− was present (8 μmol/g soil or 0.4 μmol/ml culture). Since C2 H2 inhibition of the reduction of N2 O is used as a tool in the assay of denitrification, the presence in large numbers of such a Cytophaga may influence the effectiveness of this assay especially in sulfidic environments. 相似文献
16.
Oxygen control prevents denitrifiers and barley plant roots from directly competing for nitrate 总被引:1,自引:0,他引:1
Abstract Two denitrifying bacteria ( Pseudomonas chlororaphis and P. aureofaciens ) and a plant (barley, Hordeum vulgare ) were used to study the effect of O2 concentration on denitrification and NO3 − uptake by roots under well-defined aeration conditions. Bacterial cells in the early stationary phase were kept in a chemostat vessel with vigorous stirring and thus a uniform O2 concentration in the solution. Both Pseudomonads lacked N2 O reductase and so total denitrification could be directly measured as N2 O production.
Denitrification decreased to 6–13% of the anaerobic rate at 0.01% O2 saturation (0.14 μM O2 ) and was totally inhibited at 0.04% O2 saturation (0.56 μM O2 ). In this well-mixed system denitrification was 10-times more oxygen sensitive than stated in earlier reports. Uptake of nitrate by plants was measured in the same system under light. The NO3 − uptake rate decreased gradually from a maximum in 21% O2 -saturated medium (air saturated) to zero at 1.6% O2 saturation (22.4 μM O2 ). Owing to the very different non-overlapping oxygen requirements of the two processes, direct competition for nitrate between plant roots and denitrifying bacteria cannot occur. 相似文献
Denitrification decreased to 6–13% of the anaerobic rate at 0.01% O
17.
Biogeographical distribution of diverse anaerobic ammonium oxidizing (anammox) bacteria in Cape Fear River Estuary 总被引:7,自引:0,他引:7
Summary Anaerobic ammonium oxidation (anammox) specific PCR method was developed to examine diversity and distribution of anammox bacteria in sediments collected from three different sites at Cape Fear River Estuary, North Carolina, where environmental parameters vary greatly over the year. Abundance and activities of anammox bacteria in these sediments were measured using the quantitative PCR (Q-PCR) method and 15 N isotope tracer incubations. Different anammox bacterial communities composed with Brocadia , Kuenenia , Jettenia or Scalindua were found among sites along the estuarine gradient. Seasonal variations of anammox community structures were observed along the estuary based on terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA genes. Correlation analysis suggested that salinity variation influenced the diversity and distribution of different anammox bacteria in the estuary. Q-PCR assays of anammox bacteria showed temporal and spatial variations of their abundances, which were highly correlated to salinity variation. 15 N isotope tracer incubations measured different anammox rates and its per cent contribution to total N2 production among sites. The highest anammox rate was found at the site where Scalindua organisms dominated with the highest anammox bacterial abundance. Thus, we demonstrated a biogeographical distribution of diverse anammox bacteria influenced by salinity, and provide evidence to link anammox abundance and activities in estuarine sediments. 相似文献
18.
Carbon (C) and nitrogen (N) are strongly coupled across ecosystems due to stoichiometrically balanced assimilatory demand as well as dissimilatory processes such as denitrification. Microorganisms mediate these biogeochemical cycles, but how microbial communities respond to environmental changes, such as dissolved organic carbon (DOC) availability, and how those responses impact coupled biogeochemical cycles in streams is not clear. We enriched a stream in central Indiana with labile DOC for 5?days to investigate coupled C and N cycling. Before, and on day 5 of the enrichment, we examined assimilatory uptake and denitrification using whole-stream 15N-nitrate tracer additions and short-term nitrate releases. Concurrently, we measured bacterial and denitrifier abundance and community structure. We predicted N assimilation and denitrification would be stimulated by the addition of labile C and would be mediated by increases in bacterial activity, abundance, and a shift in community structure. In response to the twofold increase in DOC concentrations in the water column, N assimilation increased throughout the enrichment. Community respiration doubled during the enrichment and was associated with a change in bacterial community structure (based on terminal restriction fragment length polymorphisms of the 16S rRNA gene). In contrast, there was little response in denitrification or denitrifier community structure, likely because labile C was assimilated by heterotrophic communities on the stream bed prior to reaching denitrifiers within the sediments. Our results suggest that coupling between C and N in streams involves potentially complex interactions with sediment texture and organic matter, microbial community structure, and possibly indirect biogeochemical pathways. 相似文献
19.
Effects of oxygen, pH and nitrate concentration on denitrification by Pseudomonas species 总被引:2,自引:0,他引:2
Abstract The production of nitrogen-containing gases by denitrification in three organisms was examined using membrane inlet mass spectrometry. The effects of O2 (during both growth and maintenance) and of pH, nitrate concentration and carbon source were tested in non-proliferating cell suspensions. Two strains of Pseudomonas aeruginosa were capable of co-respiration of NO3 − and O2 and, under controlled O2 supply, gave oscillatory denitrification. Variations in culture and assay conditions affected both the rate of denitrification and the ratio of end products (N2 O:N2 ). Higher rates were seen following anaerobic growth. Optimum values of pH and nitrate concentration for denitrification are given. Generally, the optimum pH was 7.0–7.5, approximately that of the growth medium. Optimum nitrate concentration was generally 20 mM. 相似文献
20.
Claire E. Moulton-Brown Tianer Feng Shreiya Shivagni Kumar Luxi Xu Calvin Dytham Thorunn Helgason Julia M. Cooper James W. B. Moir 《Environmental microbiology》2022,24(1):298-308
Denitrification causes loss of available nitrogen from soil systems, thereby reducing crop productivity and increasing reliance on agrochemicals. The dynamics of denitrification and denitrifying communities are thought to be altered by land management practices, which affect the physicochemical properties of the soil. In this study, we look at the effects of long-term tillage and fertilization regimes on arable soils following 16 years of treatment in a factorial field trial. By studying the bacterial community composition based on 16S rRNA amplicons, absolute bacterial abundance and diversity of denitrification functional genes (nirK, nirS and nosZ), under conditions of minimum/conventional tillage and organic/synthetic mineral fertilizer, we tested how specific land management histories affect the diversity and distribution of both bacteria and denitrification genes. Bacterial and denitrifier communities were largely unaffected by land management history and clustered predominantly by spatial location, indicating that the variability in bacterial community composition in these arable soils is governed by innate environmental differences and Euclidean distance rather than agricultural management intervention. 相似文献