A two-year field experiment conducted under dryland conditions in semi-humid and drought-prone regions of China aimed to assess the effect of ammonia-oxidizing bacterial on maize water use efficiency and yield.A heter...A two-year field experiment conducted under dryland conditions in semi-humid and drought-prone regions of China aimed to assess the effect of ammonia-oxidizing bacterial on maize water use efficiency and yield.A heterotrophic ammonia-oxidizing bacteria(HAOB)strain S2_8_1 was used.Six treatments were applied:(1)no irrigation+HAOB strain(DI),(2)no irrigation+blank culture medium(DM),(3)no irrigation control(DCK),(4)irrigation+HAOB(WI),(5)irrigation+blank culture medium(WM),and(6)irrigation control(WCK).Results revealed that HAOB treatment increased maize growth,yield,and water use efficiency over controls,regardless of whether the year was wet or dry.This improvement was attributed to the accelerated nitrification in the rhizosphere soil due to HAOB inoculation,which subsequently led to increased levels of leaf cytokinins.Overall,these findings suggest that HAOB inoculation holds promise as a strategy to boost water use efficiency and maize productivity in dryland agriculture.展开更多
In order to explore the nitrogen removal process in constructed wetlands(CW s),the moisture,ammonia nitrogen(NH4+-N),nitrate nitrogen(NO3"-N)and nitrification intensity in three wetland plant rhizosphere soils(Ac...In order to explore the nitrogen removal process in constructed wetlands(CW s),the moisture,ammonia nitrogen(NH4+-N),nitrate nitrogen(NO3"-N)and nitrification intensity in three wetland plant rhizosphere soils(Acorns calamus,Typha orientalis,Iris pseudacorus)were investigated at a relatively normal temperature range of15to25The relative abundance of ammonia-oxidizing bacteria(AOB)and ammonia-oxidizing archaea(AOA)were also achieved using fluorescence in situ hybridization(FISH).It is found that T.orientalis achieves the highest nitrification intensity of2.03m g(h?kg)while the second is I.pseudacorrs(1.74m g/(h?kg)),and followed by A.calamus(1.65m g/(h?kg))throughout the experiment.FISH reveals that the abundance of bacteria(1010g_1wet soil)is higher than that of archaea(109g_1wet soil),and AOBare the dominant bacteria in the ammonia oxidation process.The abundance of AOB in te rhizosphere soils from high to low T.orientalis(1.88x1010g"1),I pseudacorus(1.23x1010g1),A.calamus(5.07x109g"1)while the abundance of AOA from high to low ae I.pseudacorus(4.00x109g1),A.calamus(3.52x109g"1),T.orientalis(3.48x109g"1).The study provides valuable evidence of plant selection for nitrogen removal in CWs.展开更多
ObjectiveThe aim was to understand the effects of transgenic DREB soybean on the ammonia-oxidizing bacteria. MethodThe diversity of the cto gene in pot-planted transgenic soybean and near-isogenic non-transgenic soybe...ObjectiveThe aim was to understand the effects of transgenic DREB soybean on the ammonia-oxidizing bacteria. MethodThe diversity of the cto gene in pot-planted transgenic soybean and near-isogenic non-transgenic soybean under normal water condition and drought stress was analyzed by PCR-DGGE and sequence analysis. ResultRhizosphere community diversity of ammonia-oxidizing bacteria showed no difference between the treatments of transgenic soybean and its non-transgenic isolines, moreover transgenic soybean under normal water condition and drought stress improved the diversity of the ammonia-oxidizing bacteria in the harvest time. The phylogenetic analysis revealed that all the sequences of excised DGGE bands were closely related to members of the genus Nitrosovibrio and Nitrosospira of the β-subclass Proteobacteria. ConclusionTransgenic DREB soybean has no adverse impact on soil ammonia-oxidizing bacteria.展开更多
We investigated the communities of ammonia-oxidizing bacteria (AOB) in activated sludge collected from eight wastewater treatment systems using polymerase chain reaction (PCR) followed by terminal restriction frag...We investigated the communities of ammonia-oxidizing bacteria (AOB) in activated sludge collected from eight wastewater treatment systems using polymerase chain reaction (PCR) followed by terminal restriction fragment length polymorphism (T-RFLP), cloning, and sequencing of the α-subunit of the ammonia monooxygenase gene (amoA). The T-RFLP fingerprint analyses showed that different wastewater treatment systems harbored distinct AOB communities. However, there was no remarkable difference among the AOB T- RFLP profiles from different parts of the same system. The T-RFLP fingerprints showed that a full-scale wastewater treatment plant (WWTP) contained a larger number of dominant AOB species than a pilot-scale reactor. The source of influent affected the AOB community, and the WWTPs treating domestic wastewater contained a higher AOB diversity than those receiving mixed domestic and industrial wastewater. However, the AOB community structure was little affected by the treatment process in this study. Phylogenetic analysis of the cloned amoA genes clearly indicated that all the dominant AOB in the systems was closely related to Nitrosomonas spp. not to Nitrosospira spp. Members of the Nitrosomonas oligotropha and Nitrosomonas communis clusters were found in all samples, while members of Nitrosomonas europaea cluster occurred in some systems.展开更多
The spatial distribution of ammonia-oxidizing Betaproteobacteria (βAOB) was investigated by FISH (fluorescence in situ hybridization) and DGGE (denaturing gradient get electrophoresis) techniques in the sedimen...The spatial distribution of ammonia-oxidizing Betaproteobacteria (βAOB) was investigated by FISH (fluorescence in situ hybridization) and DGGE (denaturing gradient get electrophoresis) techniques in the sediment off the Changjiang River Estuary. Sediment samples were collected from eight stations in June before the formation of hypoxia zone in 2006. The abundance of βAOB ranged from 1.87× 10^5 to 3.53×10^5 cells/g of sediment. βAOB abundance did not present a negative correlation with salinity, whereas salinity was implicated as the primary factor affecting nitrification rates. The DGGE profiles of PCR-amplified amoA gene fragments revealed that the βAOB community structure of sample S2 separated from other samples at the level of 40% similarity. The variations in composition ofβAOB were significantly correlated with the salinity, temperature, absorption ability of sediments and TOC. The statistical analysis indicates that theβAOB abundance was a main factor to influence nitrification rates with an influence ratio of 87.7% at the level of 40% biodiversity similarity. Considering the good correlation between βAOB abundance and nitrification estimates, the abundance and diversity of βAOB community could be expected as an indirect index of nitrification activity at the study sea area in summer.展开更多
Acetochlor is an increasingly used herbicide on corn in North China. Currently, the effect of acetochlor on soil ammonia-oxidizing bacteria (AOB) communities is not well documented. Here, we studied the diversity and ...Acetochlor is an increasingly used herbicide on corn in North China. Currently, the effect of acetochlor on soil ammonia-oxidizing bacteria (AOB) communities is not well documented. Here, we studied the diversity and community composition of AOB in soil amended with three concentrations of acetochlor (50, 150, 250 mg/kg) and the control (0 mg acetochlor/kg soil) in a microcosm experiment by PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) and the phylogenetic analysis of excised ...展开更多
Ammonia oxidation plays a significant role in the nitrogen cycle in marine sediments. Seasonal and spatial distribution of ammonia-oxidizing archaea (AOA) and betaproteobacteria (13-AOB) in surface sediments from ...Ammonia oxidation plays a significant role in the nitrogen cycle in marine sediments. Seasonal and spatial distribution of ammonia-oxidizing archaea (AOA) and betaproteobacteria (13-AOB) in surface sediments from the East China Sea (ECS) were investigated using ammonia monooxygenase ct subunit (amoA) gene. In order to characterize the community of AOA and 13-AOB, real-time quantitative polymerase chain reaction (qPCR) was carried out in this study, along with environmental parameters. The abundance of 13-AOB amoA gene (2.17x 10^6-4.54x10^7 copy numbers per gram wet weight sediment) was always greater than that ofAOA amoA gene (2.18x 105-9.89x 10^6 copy numbers per gram wet weight sediment) in all sampling stations. The qPCR results were correlated with environmental parameters. AOA amoA gene copy numbers in April were positively related to temperature and nitrite concentration (p〈0.05). 13-AOB amoA gene copy numbers in August correlated negatively with salinity (p〈0.01), and correlated positively with ammonium concentration (p〈0.05). With the increase of salinity, the amoA gene copy ratio of AOB to AOA had a tendency to decrease, which suggested 13-AOB dominated in the area of high level ammonium and AOA preferred high salinity area.展开更多
This study examines the impacts of short-term(6 months) fertilization on the community structure and abundance of ammonia-oxidizing betaproteobacteria(β-AOB) and the potential nitrification rate in sediment colonized...This study examines the impacts of short-term(6 months) fertilization on the community structure and abundance of ammonia-oxidizing betaproteobacteria(β-AOB) and the potential nitrification rate in sediment colonized by S uaeda heteroptera in a saltmarsh located in Shuangtai estuary, China. The sediment samples were collected from plots treated with different amounts of an N fertilizer(urea supplied at 0.1, 0.2, 0.4, and 0.8 g/kg(nitrogen content in dry sediment)), and with different forms of N fertilizers(urea,(NH4) 2 SO 4, and NH_4NO_3, each supplied at 0.2 g/kg). The fertilizers were applied 1–4 times during the plant-growing season in May, July, August and September of 2013. Untreated plots were included as a control. As revealed in denaturing gradient gel electrophoresis of the 16 S r RNA gene, the β-AOB community responded to both the amount and form of N. Real-time quantitative PCR indicated that both abundance and potential nitrification rate of β-AOB increased after N addition, regardless of concentration and form(except NH_4NO_3). These results provide evidence that short-term N application influences the sediment β-AOB community, β-AOB abundance and potential nitrification rate in a saltmarsh ecosystem.展开更多
Soil nitrification is mediated by ammonia-oxidizing archaea (AOA) and bacteria (AOB), which occupy different specialized ecological niches. However, little is known about the diversification of AOA and AOB communities...Soil nitrification is mediated by ammonia-oxidizing archaea (AOA) and bacteria (AOB), which occupy different specialized ecological niches. However, little is known about the diversification of AOA and AOB communities in a large geographical scale. Here, eight paddy soils collected from different geographic regions in China were selected to investigate the spatial distribution of AOA and AOB, and their potential nitrification activity (PNA). The result showed that the abundance of AOA was predominant over AOB, indicating that the rice fields favor the growth of AOA. PNA highly varied from 0.43 to 3.57 μg NOX-N·g·dry·soil·h-1, and was positively related with soil NH3 content, the abundance of AOA community, and negatively related with the diversity of AOB community (P amoA genes revealed remarkable differences in the compositions of AOA and AOB community. Phylogenetic analyses of amoA genes showed that Nitrosospiracluster-3-like and Nitrosomonas cluster 7-like AOB extensively dominated the AOB communities, and 54d9-like AOA within the soil group 1.1b predominated in AOA communities in paddy soils. Redundancy analysis suggested that the spatial variations of AOA community structure were influenced by soil TN content (P < 0.01), while no significant correlation between AOB community structure and soil properties was found. Findings highlight that ammonia oxidizers exhibit spatial variations in complex paddy fields due to the joint influence of soil variables associated with N availability.展开更多
We investigated the changes in communities of bacteria,ammonia-oxidizing bacteria,and Nitrospira during the operation of a pufferfish Takifugu rubripes recirculating aquaculture system by using high-throughput DNA seq...We investigated the changes in communities of bacteria,ammonia-oxidizing bacteria,and Nitrospira during the operation of a pufferfish Takifugu rubripes recirculating aquaculture system by using high-throughput DNA sequencing.Differences in bacterial communities were observed at days 1-32,47-62 and 78-93 of biofilm development by using 16S rRNA gene pyrosequencing.The relative abundance of Proteobacteria(Gammaproteobacteria)increased,while that of Bacteroidetes(Flavobacteria)decreased.The proportions of Nitrosomonas and Nitrospina ranged from 0.02%to 0.30%and from 0.02%to 0.83%,respectively.Ammonia monooxygenase gene pyrosequencing revealed that the top three operational taxonomic units were related to Nitrosomonas aestuarii(17.5%-61.1%),uncultured beta proteobacterium clone B67S-54(1.9%-45.2%),and uncultured bacterium clone AZPa8(3.6%-24.7%).Nitrite oxidoreductase gene pyrosequencing revealed that the relative abundance of the dominant strain Nitrospira sp.Ecomares 2.1 increased,but that of the abundant species Nitrospira marina decreased.Our results demonstrated that the communities of bacteria,ammonia-oxidizing bacteria,and Nitrospira were changing during the operation of the pufferfish recirculating aquaculture system.展开更多
A molecular biology method, fluorescent in situ hybridization(FISH), in which the pre-treatment was improved in allusion to the media of the constructed wetlands(CW), e.g. the soil and the grit, was used to invest...A molecular biology method, fluorescent in situ hybridization(FISH), in which the pre-treatment was improved in allusion to the media of the constructed wetlands(CW), e.g. the soil and the grit, was used to investigate the vertical distribution characteristics of ammonia-oxidizing bacteria(AOB) quantity and the relation with oxidation-reduction potential(ORP) in the Typha latifolia constructed wetlands under three different Ioadings in summer from May to September. Results showed that the quantity of the AOB decreased in the Typha latifolia CW with the increase of vertical depth. However, the AOB quantity was 2-4 times the quantity of the control in the root area. Additionally, ORP in the rhizosphere was found to be higher than other areas, which showed that Typha latifolia CW was in an aerobic state in summer when using simulated non-point sewage at the rural area of Taihu Lake in China and small town combined sewage.展开更多
In this study, we investigated the potential nitrification and community structure of soil-based ammonia-oxidizing bacteria (AOB) in apple orchard soil during different growth periods and explored the effects of env...In this study, we investigated the potential nitrification and community structure of soil-based ammonia-oxidizing bacteria (AOB) in apple orchard soil during different growth periods and explored the effects of environmental factors on nitrification activity and AOB community composition in the soil of a Hanfu apple orchard, using a culture-dependent technique and denaturing gradient gel electrophoresis (DGGE). We observed that nitrification activity and AOB abundance were the highest in November, lower in May, and the lowest in July. The results of statistical analysis indicated that total nitrogen (N) content, NH4+-N content, NO3-N content, and pH showed significant correlations with AOB abundance and nitrification activity in soil. The Shannon-Winner diversity, as well as species richness and evenness indices (determined by PCR-DGGE banding patterns) in soil samples were the highest in September, but the lowest in July, when compared to additional sampled dates. The DGGE fingerprints of soil-based 16S rRNA genes in November were apparently distinct from those observed in May, July, and September, possessing the lowest species richness indices and the highest dominance indices among all four growth periods. Fourteen DGGE bands were excised for sequencing. The resulting analysis indicated that all AOB communities belonged to the 13-Proteobacteria phylum, with the dominant AOB showing high similarity to the Nitrosospira genus. Therefore, soil-based environmental factors, such as pH variation and content of NHa+-N and NO3--N, can substantially influence the abundance of AOB communities in soil, and play a critical role in soil-based nitrification kinetics.展开更多
Ammonia-oxidizing archaea(AOA) are important in converting ammonia into nitrate in soils. While many aspects of their community structure have been studied, the relative importance of stochastic versus deterministic p...Ammonia-oxidizing archaea(AOA) are important in converting ammonia into nitrate in soils. While many aspects of their community structure have been studied, the relative importance of stochastic versus deterministic processes has poorly been understood. We compared AOA communities across the North China Plain, targeting the amoA gene. A phylogenetic null modelling approach was used to calculate the beta nearest taxon index to quantify the influence of stochastic and deterministic processes. We found that spatial distance between samples predicted the perceived processes involved in community structuring, with stochastic processes dominating at local scales. At greater distances, stochasticity became weaker. However, soil pH, which was also the strongest determinant of AOA community, was a much stronger predictor of community structuring, leaving the distance effect redundant as an explanation of community structuring processes. The communities of AOA differing by less than 1 pH unit differed mainly stochastically in terms of operational taxonomic unit composition. At larger pH differences, deterministic processes based on heterogeneous selection between clades became increasingly dominant. It appears that AOA community composition is largely determined by the environment. However, very similar pH environments are the exception. In environments with very close pH values, stochastic effects dominantly cause differences in community composition, whether spatially near or far.展开更多
The abundance of ammonia-oxidizing bacteria and archaea and their amo A genes from the aerobic activated sludge tanks,recycled sludge and anaerobic digesters of a full-scale wastewater treatment plant(WWTP)was determi...The abundance of ammonia-oxidizing bacteria and archaea and their amo A genes from the aerobic activated sludge tanks,recycled sludge and anaerobic digesters of a full-scale wastewater treatment plant(WWTP)was determined.Polymerase chain reaction and denaturing gradient gel electrophoresis were used to generate diversity profiles,which showed that each population had a consistent profile although the abundance of individual members varied.In the aerobic tanks,the ammonia-oxidizing bacterial(AOB)population was more than 350 times more abundant than the ammonia-oxidizing archaeal(AOA)population,however in the digesters,the AOA population was more than 10 times more abundant.Measuring the activity of the amo A gene expression of the two populations using RT-PCR also showed that the AOA amo A gene was more active in the digesters than in the activated sludge tanks.Using batch reactors and dd PCR,amo A activity could be measured and it was found that when the AOB amo A activity was inhibited in the anoxic reactors,the expression of the AOA amo A gene increased fourfold.This suggests that these two populations may have a cooperative relationship for the oxidation of ammonia.展开更多
Ammonia-oxidizing bacteria(AOB)and archaea(AOA)are two microbial groups mediating nitrification,yet little is presently known about their abundances and community structures at the transcriptional level in wastewater ...Ammonia-oxidizing bacteria(AOB)and archaea(AOA)are two microbial groups mediating nitrification,yet little is presently known about their abundances and community structures at the transcriptional level in wastewater treatment systems(WWTSs).This is a significant issue,as the numerical abundance of AOA or AOB at the gene level may not necessarily represent their functional role in ammonia oxidation.Using amo A genes as molecular markers,this study investigated the transcriptional abundance and community structure of active AOA and AOB in 14 WWTSs.Quantitative PCR results indicated that the transcriptional abundances of AOB amo A(averaged:1.6×10^(8)copies g^(-1)dry sludge)were higher than those of AOA(averaged:3.4×10^(7)copies g^(-1)dry sludge)in all WWTSs despite several higher abundances of AOA amo A at the gene level.Moreover,phylogenetic analysis demonstrated that Nitrosomonas europaea and unknown clusters accounted for 37.66%and 49.96%of the total AOB amo A transcripts,respectively,suggesting their dominant role in driving ammonia oxidation.Meanwhile,AOA amo A transcripts were only successfully retrieved from 3 samples,and the Nitrosospaera sister cluster dominated,accounting for 83.46%.Finally,the substrate utilization kinetics of different AOA and AOB species might play a fundamental role in shaping their niche differentiation,community composition,and functional activity.This study provides a basis for evaluating the relative contributions of ammonia-oxidizing microorganisms(AOMs)to nitrogen conversions in WWTSs.展开更多
As low oxygen and high ultraviolet (UV) exposure might significantly affect the microbial existence in plateau, it could lead to a specialized microbial community. To determine the abundance and distribution of ammo...As low oxygen and high ultraviolet (UV) exposure might significantly affect the microbial existence in plateau, it could lead to a specialized microbial community. To determine the abundance and distribution of ammonia-oxidizing archaea (AOA) in agricultural soil of plateau, seven soil samples were collected respectively from farmlands in Tibet and Yunnan cultivating the wheat, highland-barley, and colza, which are located at altitudes of 3200-3800 m above sea level. Quantitative PCR (q-PCR) and clone library targeting on amoA gene were used to quantify the abundances of AOA and ammonia-oxidizing bacteria (AOB), and characterize the community structures of AOA in the samples. The number of AOA cells (9.34 × 10^7-2.32× 10^8 g^-1 soil) was 3.86-21.84 times greater than that of AOB cells (6.91 × 10^6-1.24 × 10^8 g^-1 soil) in most of the samples, except a soil sample cultivating highland- barley with an AOA/AOB ratio of 0.90. Based Kendall's correlation coefficient, no remarkable correlation between AOA abundance and the environmental factor was observed. Additionally, the diversities of AOA community were affected by total nitrogen and organic matter concentration in soils, suggesting that AOA was probably sensitive to several environmental factors, and could adjust its community structure to adapt to the environmental variation while maintaining its abundance.展开更多
Autotrophic ammonia-oxidizing bacteria (AOB) have been widely studied in constructed wetlands systems, while mixotrophic AOB have been less thoroughly examined. Heterotrophic bacteria were isolated from wastewater a...Autotrophic ammonia-oxidizing bacteria (AOB) have been widely studied in constructed wetlands systems, while mixotrophic AOB have been less thoroughly examined. Heterotrophic bacteria were isolated from wastewater and rhizospheres of macrophytes of constructed wetlands, and then cultivated in a mixotrophic medium containing ammonium and acetic acid. A molecular characterization was accomplished using ITS-PCR amplification, and phylogenetic analysis based on 16S rRNA gene Sequences. Results showed the presence of 35 bacteria, among 400 initially heterotrophic isolates, that were able to remove ammonia. These 35 isolates were classified into 10 genetically different groups based on ITS pattern. Then, a collection of 10 isolates were selected because of their relatively high ammonia removal efficiencies (ARE≥ 80%) and their phylogenetic diversity. In conditions of mixotrophy, these strains were shown to be able to grow (increase of optical density OD660 during incubation with assimilation of nitrogen into cellular biomass) and to oxidize ammonia (important ammonia oxidation efficiencies, AOE between 79% and 87%). Among these facultative mixotrophic AOB, four isolates were genetically related to Firmicutes (Bacillus and Exiguobacterium), three isolates were affiliated to Actinobacteria (Arthrobacter) and three other isolates were associated with Proteobacteria (Pseudomonas, Ochrobactrum and Bordetella).展开更多
Tidal flats are soil resources of great significance.Nitrification plays a central role in the nitrogen cycle and is often a critical first step in nitrogen removal from estuarine and coastal environments.We determine...Tidal flats are soil resources of great significance.Nitrification plays a central role in the nitrogen cycle and is often a critical first step in nitrogen removal from estuarine and coastal environments.We determined the abundance as well as composition of ammonia-oxidizing bacteria(AOB) and ammonia-oxidizing archaea(AOA) in different soils during land reclamation process.The abundance of AOA was higher than that of AOB in farm land and wild land while AOA was not detected in tidal flats using real-time polymerase chain reaction(PCR).The different abundances of AOB and AOA were negatively correlated with the salinity.The diversities of AOB and AOA were also investigated using clone libraries by amplification of amoA gene.Among AOB,nearly all sequences belonged to the Nitrosomonas lineage in the initial land reclamation process,i.e.,tidal flats,while both Nitrosomonas and Nitrosospira lineages were detected in later and transition phases of land reclamation process,farm land and wild land.The ratio of the numbers of sequences of Nitrosomonas and Nitrosospira lineages was positively correlated with the salinity and the net nitrification rate.As for AOA,there was no obvious correlation with the changes in the physicochemical properties of the soil.This study suggests that AOB may be more import than AOA with respect to influencing the different land reclamation process stages.展开更多
Heavy metal pollution affects soil ecological function.Biochar and compost can effectively remediate heavy metals and increase soil nutrients.The effects and mechanisms of biochar and compost amendments on soil nitrog...Heavy metal pollution affects soil ecological function.Biochar and compost can effectively remediate heavy metals and increase soil nutrients.The effects and mechanisms of biochar and compost amendments on soil nitrogen cycle function in heavy-metal contaminated soils are not fully understood.This study examined how biochar,compost,and their integrated use affected ammonia-oxidizing microorganisms in heavy metal polluted soil.Quantitative PCR was used to determine the abundance of ammonia-oxidizing archaea(AOA)and bacteria(AOB).Ammonia monooxygenase(AMO)activity was evaluated by the enzymelinked immunosorbent assay.Results showed that compost rather than biochar improved nitrogen conversion in soil.Biochar,compost,or their integrated application significantly reduced the effective Zn and Cd speciation.Adding compost obviously increased As and Cu effective speciation,bacterial 16 S rRNA abundance,and AMO activity.AOB,stimulated by compost addition,was significantly more abundant than AOA throughout remediation.Correlation analysis showed that AOB abundance positively correlated with NO_(3)^(-)-N(r=0.830,P<0.01),and that AMO activity had significant correlation with EC(r=-0.908,P<0.01)and water-soluble carbon(r=-0.868,P<0.01).Those seem to be the most vital factors affecting AOB community and their function in heavy metal-polluted soil remediated by biochar and compost.展开更多
Ammonia-oxidizing archaea (AOA) are widely considered key to ammonia oxidation in various environments. However, little work has been conducted to simultaneously investigate the abundance and diversity of AOA as wel...Ammonia-oxidizing archaea (AOA) are widely considered key to ammonia oxidation in various environments. However, little work has been conducted to simultaneously investigate the abundance and diversity of AOA as well as correlations between archaeal amoA genotypes and environmental parameters of different ecosystems at one district. To understand the abundance, diversity, and distribution of AOA in Pearl River Delta of China in response to various habitats, the archaeal amoA genes in soil, marine, river, lake, hot spring and wastewater treatment plant (WWTP) samples were investigated using real-time fluorescent quantitative PCR and clone libraries. Our analyses indicated that the diversity of AOA in various habitats was different and could be clustered into five major clades, i.e., estuary sediment, marine water/sediment, soil, hot spring and Cluster 1. Phylogenetic analyses revealed that the structure of AOA communities in similar ecological habitats exhibited strong relation. The canonical correspondence method indicated that the AOA community structure was strongly correlated to temperature, pH, total organic carbon, total nitrogen and dissolved oxygen variables. Assessing AOA amoA gene copy numbers, ranging from 6.84× 10^6 to 9.45 × 10^7 copies/g in dry soil/sediment, and 6.06× 10^6 to 2.41 ×10^7 copies/L in water samples, were higher than ammonia-oxidizing bacteria (AOB) by 1-2 orders of magnitude. However, AOA amoA copy numbers were much lower than AOB in WWTP activated sludge samples. Overall, these studies suggested that AOA may be a major contributor to ammonia oxidation in natural habitats but play a minor role in highly aerated activated sludge. The result also showed the ratio of AOA to AOB amoA gene abundance was positively correlated with temperature and less correlated with other environmental parameters. New data from our study provide increasing evidence for the relative abundance and diversity of ammonia-oxidizing archaea in the global nitrogen cycle.展开更多
基金supported by the National Natural Science Foundation of China(U1304326)the Natural Science Foundation of Henan Provincial(242300421242)。
文摘A two-year field experiment conducted under dryland conditions in semi-humid and drought-prone regions of China aimed to assess the effect of ammonia-oxidizing bacterial on maize water use efficiency and yield.A heterotrophic ammonia-oxidizing bacteria(HAOB)strain S2_8_1 was used.Six treatments were applied:(1)no irrigation+HAOB strain(DI),(2)no irrigation+blank culture medium(DM),(3)no irrigation control(DCK),(4)irrigation+HAOB(WI),(5)irrigation+blank culture medium(WM),and(6)irrigation control(WCK).Results revealed that HAOB treatment increased maize growth,yield,and water use efficiency over controls,regardless of whether the year was wet or dry.This improvement was attributed to the accelerated nitrification in the rhizosphere soil due to HAOB inoculation,which subsequently led to increased levels of leaf cytokinins.Overall,these findings suggest that HAOB inoculation holds promise as a strategy to boost water use efficiency and maize productivity in dryland agriculture.
基金The National Natural Science Foundation of China(No.51479034,50909019)the Fundamental Research Funds for the Central Universities
文摘In order to explore the nitrogen removal process in constructed wetlands(CW s),the moisture,ammonia nitrogen(NH4+-N),nitrate nitrogen(NO3"-N)and nitrification intensity in three wetland plant rhizosphere soils(Acorns calamus,Typha orientalis,Iris pseudacorus)were investigated at a relatively normal temperature range of15to25The relative abundance of ammonia-oxidizing bacteria(AOB)and ammonia-oxidizing archaea(AOA)were also achieved using fluorescence in situ hybridization(FISH).It is found that T.orientalis achieves the highest nitrification intensity of2.03m g(h?kg)while the second is I.pseudacorrs(1.74m g/(h?kg)),and followed by A.calamus(1.65m g/(h?kg))throughout the experiment.FISH reveals that the abundance of bacteria(1010g_1wet soil)is higher than that of archaea(109g_1wet soil),and AOBare the dominant bacteria in the ammonia oxidation process.The abundance of AOB in te rhizosphere soils from high to low T.orientalis(1.88x1010g"1),I pseudacorus(1.23x1010g1),A.calamus(5.07x109g"1)while the abundance of AOA from high to low ae I.pseudacorus(4.00x109g1),A.calamus(3.52x109g"1),T.orientalis(3.48x109g"1).The study provides valuable evidence of plant selection for nitrogen removal in CWs.
基金Supported by the Special Scientific Fund for Non-profit Environmental Industry(2010467038)~~
文摘ObjectiveThe aim was to understand the effects of transgenic DREB soybean on the ammonia-oxidizing bacteria. MethodThe diversity of the cto gene in pot-planted transgenic soybean and near-isogenic non-transgenic soybean under normal water condition and drought stress was analyzed by PCR-DGGE and sequence analysis. ResultRhizosphere community diversity of ammonia-oxidizing bacteria showed no difference between the treatments of transgenic soybean and its non-transgenic isolines, moreover transgenic soybean under normal water condition and drought stress improved the diversity of the ammonia-oxidizing bacteria in the harvest time. The phylogenetic analysis revealed that all the sequences of excised DGGE bands were closely related to members of the genus Nitrosovibrio and Nitrosospira of the β-subclass Proteobacteria. ConclusionTransgenic DREB soybean has no adverse impact on soil ammonia-oxidizing bacteria.
基金supported by the Key Projects in National Science & Technology Pillar Program during the Eleventh Five-Year Plan Period (No.2006BAC19B01-02)the Mega-projects of Science Research for Water (No.2008ZX07313-3)the Program of Introducing Talents of Discipline to Universities
文摘We investigated the communities of ammonia-oxidizing bacteria (AOB) in activated sludge collected from eight wastewater treatment systems using polymerase chain reaction (PCR) followed by terminal restriction fragment length polymorphism (T-RFLP), cloning, and sequencing of the α-subunit of the ammonia monooxygenase gene (amoA). The T-RFLP fingerprint analyses showed that different wastewater treatment systems harbored distinct AOB communities. However, there was no remarkable difference among the AOB T- RFLP profiles from different parts of the same system. The T-RFLP fingerprints showed that a full-scale wastewater treatment plant (WWTP) contained a larger number of dominant AOB species than a pilot-scale reactor. The source of influent affected the AOB community, and the WWTPs treating domestic wastewater contained a higher AOB diversity than those receiving mixed domestic and industrial wastewater. However, the AOB community structure was little affected by the treatment process in this study. Phylogenetic analysis of the cloned amoA genes clearly indicated that all the dominant AOB in the systems was closely related to Nitrosomonas spp. not to Nitrosospira spp. Members of the Nitrosomonas oligotropha and Nitrosomonas communis clusters were found in all samples, while members of Nitrosomonas europaea cluster occurred in some systems.
基金The National Fundamental Project of China under grant No.2006CB400602
文摘The spatial distribution of ammonia-oxidizing Betaproteobacteria (βAOB) was investigated by FISH (fluorescence in situ hybridization) and DGGE (denaturing gradient get electrophoresis) techniques in the sediment off the Changjiang River Estuary. Sediment samples were collected from eight stations in June before the formation of hypoxia zone in 2006. The abundance of βAOB ranged from 1.87× 10^5 to 3.53×10^5 cells/g of sediment. βAOB abundance did not present a negative correlation with salinity, whereas salinity was implicated as the primary factor affecting nitrification rates. The DGGE profiles of PCR-amplified amoA gene fragments revealed that the βAOB community structure of sample S2 separated from other samples at the level of 40% similarity. The variations in composition ofβAOB were significantly correlated with the salinity, temperature, absorption ability of sediments and TOC. The statistical analysis indicates that theβAOB abundance was a main factor to influence nitrification rates with an influence ratio of 87.7% at the level of 40% biodiversity similarity. Considering the good correlation between βAOB abundance and nitrification estimates, the abundance and diversity of βAOB community could be expected as an indirect index of nitrification activity at the study sea area in summer.
基金the Natural Science Foun-dation for Young Scientists of China (No. 40701088)
文摘Acetochlor is an increasingly used herbicide on corn in North China. Currently, the effect of acetochlor on soil ammonia-oxidizing bacteria (AOB) communities is not well documented. Here, we studied the diversity and community composition of AOB in soil amended with three concentrations of acetochlor (50, 150, 250 mg/kg) and the control (0 mg acetochlor/kg soil) in a microcosm experiment by PCR-DGGE (polymerase chain reaction-denaturing gradient gel electrophoresis) and the phylogenetic analysis of excised ...
基金The National Natural Science Foundation of China under contract No.40920164004the National Basic Research Program (973 Program) of China under contract No.2011CB403602the Foundation for Innovative Research Groups of the National Natural Science Foundation of China under contract No.41221004
文摘Ammonia oxidation plays a significant role in the nitrogen cycle in marine sediments. Seasonal and spatial distribution of ammonia-oxidizing archaea (AOA) and betaproteobacteria (13-AOB) in surface sediments from the East China Sea (ECS) were investigated using ammonia monooxygenase ct subunit (amoA) gene. In order to characterize the community of AOA and 13-AOB, real-time quantitative polymerase chain reaction (qPCR) was carried out in this study, along with environmental parameters. The abundance of 13-AOB amoA gene (2.17x 10^6-4.54x10^7 copy numbers per gram wet weight sediment) was always greater than that ofAOA amoA gene (2.18x 105-9.89x 10^6 copy numbers per gram wet weight sediment) in all sampling stations. The qPCR results were correlated with environmental parameters. AOA amoA gene copy numbers in April were positively related to temperature and nitrite concentration (p〈0.05). 13-AOB amoA gene copy numbers in August correlated negatively with salinity (p〈0.01), and correlated positively with ammonium concentration (p〈0.05). With the increase of salinity, the amoA gene copy ratio of AOB to AOA had a tendency to decrease, which suggested 13-AOB dominated in the area of high level ammonium and AOA preferred high salinity area.
基金Supported by the National Natural Science Foundation of China(No.41171389)the Public Science and Technology Research Funds Projects of Ocean(No.201305043)the Program for Liaoning Excellent Talents in University(No.LR2013035)
文摘This study examines the impacts of short-term(6 months) fertilization on the community structure and abundance of ammonia-oxidizing betaproteobacteria(β-AOB) and the potential nitrification rate in sediment colonized by S uaeda heteroptera in a saltmarsh located in Shuangtai estuary, China. The sediment samples were collected from plots treated with different amounts of an N fertilizer(urea supplied at 0.1, 0.2, 0.4, and 0.8 g/kg(nitrogen content in dry sediment)), and with different forms of N fertilizers(urea,(NH4) 2 SO 4, and NH_4NO_3, each supplied at 0.2 g/kg). The fertilizers were applied 1–4 times during the plant-growing season in May, July, August and September of 2013. Untreated plots were included as a control. As revealed in denaturing gradient gel electrophoresis of the 16 S r RNA gene, the β-AOB community responded to both the amount and form of N. Real-time quantitative PCR indicated that both abundance and potential nitrification rate of β-AOB increased after N addition, regardless of concentration and form(except NH_4NO_3). These results provide evidence that short-term N application influences the sediment β-AOB community, β-AOB abundance and potential nitrification rate in a saltmarsh ecosystem.
文摘Soil nitrification is mediated by ammonia-oxidizing archaea (AOA) and bacteria (AOB), which occupy different specialized ecological niches. However, little is known about the diversification of AOA and AOB communities in a large geographical scale. Here, eight paddy soils collected from different geographic regions in China were selected to investigate the spatial distribution of AOA and AOB, and their potential nitrification activity (PNA). The result showed that the abundance of AOA was predominant over AOB, indicating that the rice fields favor the growth of AOA. PNA highly varied from 0.43 to 3.57 μg NOX-N·g·dry·soil·h-1, and was positively related with soil NH3 content, the abundance of AOA community, and negatively related with the diversity of AOB community (P amoA genes revealed remarkable differences in the compositions of AOA and AOB community. Phylogenetic analyses of amoA genes showed that Nitrosospiracluster-3-like and Nitrosomonas cluster 7-like AOB extensively dominated the AOB communities, and 54d9-like AOA within the soil group 1.1b predominated in AOA communities in paddy soils. Redundancy analysis suggested that the spatial variations of AOA community structure were influenced by soil TN content (P < 0.01), while no significant correlation between AOB community structure and soil properties was found. Findings highlight that ammonia oxidizers exhibit spatial variations in complex paddy fields due to the joint influence of soil variables associated with N availability.
基金This research was supported by the National Key R&D Program of China(No.2017YFD0701700)the National Natural Science Foundation of China(Nos.31472312 and 31672673).
文摘We investigated the changes in communities of bacteria,ammonia-oxidizing bacteria,and Nitrospira during the operation of a pufferfish Takifugu rubripes recirculating aquaculture system by using high-throughput DNA sequencing.Differences in bacterial communities were observed at days 1-32,47-62 and 78-93 of biofilm development by using 16S rRNA gene pyrosequencing.The relative abundance of Proteobacteria(Gammaproteobacteria)increased,while that of Bacteroidetes(Flavobacteria)decreased.The proportions of Nitrosomonas and Nitrospina ranged from 0.02%to 0.30%and from 0.02%to 0.83%,respectively.Ammonia monooxygenase gene pyrosequencing revealed that the top three operational taxonomic units were related to Nitrosomonas aestuarii(17.5%-61.1%),uncultured beta proteobacterium clone B67S-54(1.9%-45.2%),and uncultured bacterium clone AZPa8(3.6%-24.7%).Nitrite oxidoreductase gene pyrosequencing revealed that the relative abundance of the dominant strain Nitrospira sp.Ecomares 2.1 increased,but that of the abundant species Nitrospira marina decreased.Our results demonstrated that the communities of bacteria,ammonia-oxidizing bacteria,and Nitrospira were changing during the operation of the pufferfish recirculating aquaculture system.
文摘A molecular biology method, fluorescent in situ hybridization(FISH), in which the pre-treatment was improved in allusion to the media of the constructed wetlands(CW), e.g. the soil and the grit, was used to investigate the vertical distribution characteristics of ammonia-oxidizing bacteria(AOB) quantity and the relation with oxidation-reduction potential(ORP) in the Typha latifolia constructed wetlands under three different Ioadings in summer from May to September. Results showed that the quantity of the AOB decreased in the Typha latifolia CW with the increase of vertical depth. However, the AOB quantity was 2-4 times the quantity of the control in the root area. Additionally, ORP in the rhizosphere was found to be higher than other areas, which showed that Typha latifolia CW was in an aerobic state in summer when using simulated non-point sewage at the rural area of Taihu Lake in China and small town combined sewage.
基金the National Natural Science Foundation of China(31101504 and 31171917)the Postdoctoral Science Foundation of China(2011M500575)+1 种基金the China Agricultural Research System(CARS-28)the Shenyang Municipal Science and Technology Research Projects,China(F12-109-3-00)for their financial support
文摘In this study, we investigated the potential nitrification and community structure of soil-based ammonia-oxidizing bacteria (AOB) in apple orchard soil during different growth periods and explored the effects of environmental factors on nitrification activity and AOB community composition in the soil of a Hanfu apple orchard, using a culture-dependent technique and denaturing gradient gel electrophoresis (DGGE). We observed that nitrification activity and AOB abundance were the highest in November, lower in May, and the lowest in July. The results of statistical analysis indicated that total nitrogen (N) content, NH4+-N content, NO3-N content, and pH showed significant correlations with AOB abundance and nitrification activity in soil. The Shannon-Winner diversity, as well as species richness and evenness indices (determined by PCR-DGGE banding patterns) in soil samples were the highest in September, but the lowest in July, when compared to additional sampled dates. The DGGE fingerprints of soil-based 16S rRNA genes in November were apparently distinct from those observed in May, July, and September, possessing the lowest species richness indices and the highest dominance indices among all four growth periods. Fourteen DGGE bands were excised for sequencing. The resulting analysis indicated that all AOB communities belonged to the 13-Proteobacteria phylum, with the dominant AOB showing high similarity to the Nitrosospira genus. Therefore, soil-based environmental factors, such as pH variation and content of NHa+-N and NO3--N, can substantially influence the abundance of AOB communities in soil, and play a critical role in soil-based nitrification kinetics.
文摘Ammonia-oxidizing archaea(AOA) are important in converting ammonia into nitrate in soils. While many aspects of their community structure have been studied, the relative importance of stochastic versus deterministic processes has poorly been understood. We compared AOA communities across the North China Plain, targeting the amoA gene. A phylogenetic null modelling approach was used to calculate the beta nearest taxon index to quantify the influence of stochastic and deterministic processes. We found that spatial distance between samples predicted the perceived processes involved in community structuring, with stochastic processes dominating at local scales. At greater distances, stochasticity became weaker. However, soil pH, which was also the strongest determinant of AOA community, was a much stronger predictor of community structuring, leaving the distance effect redundant as an explanation of community structuring processes. The communities of AOA differing by less than 1 pH unit differed mainly stochastically in terms of operational taxonomic unit composition. At larger pH differences, deterministic processes based on heterogeneous selection between clades became increasingly dominant. It appears that AOA community composition is largely determined by the environment. However, very similar pH environments are the exception. In environments with very close pH values, stochastic effects dominantly cause differences in community composition, whether spatially near or far.
基金supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant (RGPIN/227565-2013) to K.A.G
文摘The abundance of ammonia-oxidizing bacteria and archaea and their amo A genes from the aerobic activated sludge tanks,recycled sludge and anaerobic digesters of a full-scale wastewater treatment plant(WWTP)was determined.Polymerase chain reaction and denaturing gradient gel electrophoresis were used to generate diversity profiles,which showed that each population had a consistent profile although the abundance of individual members varied.In the aerobic tanks,the ammonia-oxidizing bacterial(AOB)population was more than 350 times more abundant than the ammonia-oxidizing archaeal(AOA)population,however in the digesters,the AOA population was more than 10 times more abundant.Measuring the activity of the amo A gene expression of the two populations using RT-PCR also showed that the AOA amo A gene was more active in the digesters than in the activated sludge tanks.Using batch reactors and dd PCR,amo A activity could be measured and it was found that when the AOB amo A activity was inhibited in the anoxic reactors,the expression of the AOA amo A gene increased fourfold.This suggests that these two populations may have a cooperative relationship for the oxidation of ammonia.
基金supported by grants from the National Natural Science Foundation of China(No.41701278)Shanghai Committee of Science and Technology(No.19DZ1204302)the Fundamental Research Funds for the Central Universities(No.2019MS041)。
文摘Ammonia-oxidizing bacteria(AOB)and archaea(AOA)are two microbial groups mediating nitrification,yet little is presently known about their abundances and community structures at the transcriptional level in wastewater treatment systems(WWTSs).This is a significant issue,as the numerical abundance of AOA or AOB at the gene level may not necessarily represent their functional role in ammonia oxidation.Using amo A genes as molecular markers,this study investigated the transcriptional abundance and community structure of active AOA and AOB in 14 WWTSs.Quantitative PCR results indicated that the transcriptional abundances of AOB amo A(averaged:1.6×10^(8)copies g^(-1)dry sludge)were higher than those of AOA(averaged:3.4×10^(7)copies g^(-1)dry sludge)in all WWTSs despite several higher abundances of AOA amo A at the gene level.Moreover,phylogenetic analysis demonstrated that Nitrosomonas europaea and unknown clusters accounted for 37.66%and 49.96%of the total AOB amo A transcripts,respectively,suggesting their dominant role in driving ammonia oxidation.Meanwhile,AOA amo A transcripts were only successfully retrieved from 3 samples,and the Nitrosospaera sister cluster dominated,accounting for 83.46%.Finally,the substrate utilization kinetics of different AOA and AOB species might play a fundamental role in shaping their niche differentiation,community composition,and functional activity.This study provides a basis for evaluating the relative contributions of ammonia-oxidizing microorganisms(AOMs)to nitrogen conversions in WWTSs.
基金Acknowledgements This study was supported by the National Natural Science Foundation of China (Grant No. 51078207), and Research Fund for the Doctoral Program of High Education of China (No. 20090002770003). We wish to thank the staff of Research Platform for Modem Environmental Biologic Technology of School of Environment in Tsinghua University.
文摘As low oxygen and high ultraviolet (UV) exposure might significantly affect the microbial existence in plateau, it could lead to a specialized microbial community. To determine the abundance and distribution of ammonia-oxidizing archaea (AOA) in agricultural soil of plateau, seven soil samples were collected respectively from farmlands in Tibet and Yunnan cultivating the wheat, highland-barley, and colza, which are located at altitudes of 3200-3800 m above sea level. Quantitative PCR (q-PCR) and clone library targeting on amoA gene were used to quantify the abundances of AOA and ammonia-oxidizing bacteria (AOB), and characterize the community structures of AOA in the samples. The number of AOA cells (9.34 × 10^7-2.32× 10^8 g^-1 soil) was 3.86-21.84 times greater than that of AOB cells (6.91 × 10^6-1.24 × 10^8 g^-1 soil) in most of the samples, except a soil sample cultivating highland- barley with an AOA/AOB ratio of 0.90. Based Kendall's correlation coefficient, no remarkable correlation between AOA abundance and the environmental factor was observed. Additionally, the diversities of AOA community were affected by total nitrogen and organic matter concentration in soils, suggesting that AOA was probably sensitive to several environmental factors, and could adjust its community structure to adapt to the environmental variation while maintaining its abundance.
基金supported by a grant from the Tunisian Higher Education and Scientific Research Ministry
文摘Autotrophic ammonia-oxidizing bacteria (AOB) have been widely studied in constructed wetlands systems, while mixotrophic AOB have been less thoroughly examined. Heterotrophic bacteria were isolated from wastewater and rhizospheres of macrophytes of constructed wetlands, and then cultivated in a mixotrophic medium containing ammonium and acetic acid. A molecular characterization was accomplished using ITS-PCR amplification, and phylogenetic analysis based on 16S rRNA gene Sequences. Results showed the presence of 35 bacteria, among 400 initially heterotrophic isolates, that were able to remove ammonia. These 35 isolates were classified into 10 genetically different groups based on ITS pattern. Then, a collection of 10 isolates were selected because of their relatively high ammonia removal efficiencies (ARE≥ 80%) and their phylogenetic diversity. In conditions of mixotrophy, these strains were shown to be able to grow (increase of optical density OD660 during incubation with assimilation of nitrogen into cellular biomass) and to oxidize ammonia (important ammonia oxidation efficiencies, AOE between 79% and 87%). Among these facultative mixotrophic AOB, four isolates were genetically related to Firmicutes (Bacillus and Exiguobacterium), three isolates were affiliated to Actinobacteria (Arthrobacter) and three other isolates were associated with Proteobacteria (Pseudomonas, Ochrobactrum and Bordetella).
基金Project supported by the National Natural Science Foundation of China (Nos. 31070097 and 31011140339)the National Key Technologies R & D Program of China (Nos. 2006BAJ05A11 and2010BAK69B14)the Major Program of Science and Technology Department of Shanghai (No. 10DZ1200700),China
文摘Tidal flats are soil resources of great significance.Nitrification plays a central role in the nitrogen cycle and is often a critical first step in nitrogen removal from estuarine and coastal environments.We determined the abundance as well as composition of ammonia-oxidizing bacteria(AOB) and ammonia-oxidizing archaea(AOA) in different soils during land reclamation process.The abundance of AOA was higher than that of AOB in farm land and wild land while AOA was not detected in tidal flats using real-time polymerase chain reaction(PCR).The different abundances of AOB and AOA were negatively correlated with the salinity.The diversities of AOB and AOA were also investigated using clone libraries by amplification of amoA gene.Among AOB,nearly all sequences belonged to the Nitrosomonas lineage in the initial land reclamation process,i.e.,tidal flats,while both Nitrosomonas and Nitrosospira lineages were detected in later and transition phases of land reclamation process,farm land and wild land.The ratio of the numbers of sequences of Nitrosomonas and Nitrosospira lineages was positively correlated with the salinity and the net nitrification rate.As for AOA,there was no obvious correlation with the changes in the physicochemical properties of the soil.This study suggests that AOB may be more import than AOA with respect to influencing the different land reclamation process stages.
基金supported by the Hunan Provincial Key Research and Development Project(Nos.2019WK2031 and 2017SK2351)the National Natural Science Foundation of China(No.51408219)+1 种基金the Natural Science Foundation of Hu-nan Province(No.2020JJ5259)the Outstanding Youth Fund Project of the Hunan Education Department(No.18B094)。
文摘Heavy metal pollution affects soil ecological function.Biochar and compost can effectively remediate heavy metals and increase soil nutrients.The effects and mechanisms of biochar and compost amendments on soil nitrogen cycle function in heavy-metal contaminated soils are not fully understood.This study examined how biochar,compost,and their integrated use affected ammonia-oxidizing microorganisms in heavy metal polluted soil.Quantitative PCR was used to determine the abundance of ammonia-oxidizing archaea(AOA)and bacteria(AOB).Ammonia monooxygenase(AMO)activity was evaluated by the enzymelinked immunosorbent assay.Results showed that compost rather than biochar improved nitrogen conversion in soil.Biochar,compost,or their integrated application significantly reduced the effective Zn and Cd speciation.Adding compost obviously increased As and Cu effective speciation,bacterial 16 S rRNA abundance,and AMO activity.AOB,stimulated by compost addition,was significantly more abundant than AOA throughout remediation.Correlation analysis showed that AOB abundance positively correlated with NO_(3)^(-)-N(r=0.830,P<0.01),and that AMO activity had significant correlation with EC(r=-0.908,P<0.01)and water-soluble carbon(r=-0.868,P<0.01).Those seem to be the most vital factors affecting AOB community and their function in heavy metal-polluted soil remediated by biochar and compost.
基金supported by the National Natural Science Foundation of China (No. 50978069)
文摘Ammonia-oxidizing archaea (AOA) are widely considered key to ammonia oxidation in various environments. However, little work has been conducted to simultaneously investigate the abundance and diversity of AOA as well as correlations between archaeal amoA genotypes and environmental parameters of different ecosystems at one district. To understand the abundance, diversity, and distribution of AOA in Pearl River Delta of China in response to various habitats, the archaeal amoA genes in soil, marine, river, lake, hot spring and wastewater treatment plant (WWTP) samples were investigated using real-time fluorescent quantitative PCR and clone libraries. Our analyses indicated that the diversity of AOA in various habitats was different and could be clustered into five major clades, i.e., estuary sediment, marine water/sediment, soil, hot spring and Cluster 1. Phylogenetic analyses revealed that the structure of AOA communities in similar ecological habitats exhibited strong relation. The canonical correspondence method indicated that the AOA community structure was strongly correlated to temperature, pH, total organic carbon, total nitrogen and dissolved oxygen variables. Assessing AOA amoA gene copy numbers, ranging from 6.84× 10^6 to 9.45 × 10^7 copies/g in dry soil/sediment, and 6.06× 10^6 to 2.41 ×10^7 copies/L in water samples, were higher than ammonia-oxidizing bacteria (AOB) by 1-2 orders of magnitude. However, AOA amoA copy numbers were much lower than AOB in WWTP activated sludge samples. Overall, these studies suggested that AOA may be a major contributor to ammonia oxidation in natural habitats but play a minor role in highly aerated activated sludge. The result also showed the ratio of AOA to AOB amoA gene abundance was positively correlated with temperature and less correlated with other environmental parameters. New data from our study provide increasing evidence for the relative abundance and diversity of ammonia-oxidizing archaea in the global nitrogen cycle.