Structure Of Ammonia-oxidizing Bacterial Communities Research Articles

Evaluation of Ammonia Oxidizing Bacterial Community Structure of a Municipal Activated Sludge Plant by 454 High-Throughput Pyrosequencing

The ammonia oxidizing bacteria (AOB) community structure in a municipal wastewater treatment plant (WWTP) was monitored over the winter and summer periods. The AOB distribution in the full-scale WWTP was investigated using barcoded 454-pyrosequencing targeting the ammonia monooxygenase alpha subunit (amoA) gene. Using the quantitative polymerase chain reaction (qPCR) technique, the AOB population was quantified over 237 days. The plant operational parameters and its nitrification performance were also monitored. As revealed by pyrosequencing, majority of the identified AOB during the study were related to uncultured ammonia oxidizing bacteria, and Nitrosomonas oligotropha. Furthermore, it revealed higher AOB abundance during the summer which was 6 times more compared to winter. Substantial percentages of the reads from both seasons could not be assigned to any phylum, which suggests that vast population of novel, ecologically significant AOB species still inhabit the complex activated sludge communities unexploited. A significant seasonal variation in temperature (α = 0.05; P = < 0.0001) was recorded in the reactor with maximum temperature amplitude of 10.2 °C. The average nitrification rate recorded during the summer was 0.09 ± 0.03 g N-NH4+/g MLSS/d, whereas it was 0.04 ± 0.02 g N-NH4+/g MLSS/d during the winter. The nitrification rate of the plant had significant correlation with AOB population abundance (r = 0.70; P = 0.01) and temperature (α = 0.05; P = 0.0018). This study indicates that AOB diversity and population abundance were contributory factors to efficient nitrification in activated sludge system.

Nitrogen removal performance and ammonia- and nitrite-oxidizing bacterial community analysis of a novel industrial waste-based biofilter

This study employed a newly developed treatment biofilter to remove high nitrogen (N) concentration from synthetic livestock wastewater combined with media containing neutralized used acid (NUA) and dewatered alum sludge (DAS). This biofilter was also utilized to investigate the spatial and temporal distributions of ammonia-oxidizing bacterial (AOB) and nitrite-oxidizing bacterial (NOB) communities and their active responses to effluent characteristics. Data were obtained from 210days of operations. Results showed that N removal was robust, with ammonia N and total N removal efficiencies of 59.8–82.1% and 57.5–74.9%, respectively. Denaturing gradient gel electrophoresis and sequence analyses revealed that the shift of AOB and NOB community structures in DAS was time dependent. These structures did not exhibit distinct differences in both media as depth varied. The retrieved AOB and NOB sequences from both media primarily belonged to Nitrosomonas, Nitrosovibrio, and Nitrobacter. The nitrification rates indicated that the change in AOB activity corresponded to the AOB community structure variation in the system. The peak was observed in DAS at the final time. By contrast, the NOB activity was inconsistent with the trend of its community structure. The AOB rate was positively related to the NOB rate. This finding suggested that AOB and NOB mutually promoted each other. The AOB and NOB activities of DAS rather than those of NUA appeared dependent on available nitrate from the effluent. Overall, these findings on AOB and NOB helped enhance further understanding on the efficient N removal of the NUA–DAS system.

Effect of salinity on nitrification efficiency and structure of ammonia-oxidizing bacterial communities in a submerged fixed bed bioreactor

The effect of salt (NaCl) on biological nitrogen removal and community structure of ammonia-oxidizing bacteria (AOB) was investigated in a submerged fixed bed bioreactor (SFBBR). Influent wastewater was supplemented with NaCl at 0 (control), 3.7, 24.1 and 44.1g/L, and the rate of ammonia removal efficiency was measured by ion chromatography. The structure of the AOB community was profiled by 454-pyrosequencing, based on the amplification of partial ammonia-monooxygenase subunit A (amoA) genes. Salinity did not inhibit nitrification at 3.7g/L, while ammonia oxidation activity significantly decreased and nitrite was consequently accumulated in the SFBBR when the salt concentration was ⩾24.1g/L. The sequencing of amoA genes revealed that many of the OTUs found in the control experiment were still present at the full range of NaCl studied, while concentrations of 24.1 and 44.1g of NaCl/L promoted the emergence of new OTUs phylogenetically related to AOB described in saline environments.

Latitudinal distribution of ammonia-oxidizing bacteria and archaea in the agricultural soils of eastern China.

The response of soil ammonia-oxidizing bacterial (AOB) and archaeal (AOA) communities to individual environmental variables (e.g., pH, temperature, and carbon- and nitrogen-related soil nutrients) has been extensively studied, but how these environmental conditions collectively shape AOB and AOA distributions in unmanaged agricultural soils across a large latitudinal gradient remains poorly known. In this study, the AOB and AOA community structure and diversity in 26 agricultural soils collected from eastern China were investigated by using quantitative PCR and bar-coded 454 pyrosequencing of the amoA gene that encodes the alpha subunit of ammonia monooxygenase. The sampling locations span over a 17° latitude gradient and cover a range of climatic conditions. The Nitrosospira and Nitrososphaera were the dominant clusters of AOB and AOA, respectively; but the subcluster-level composition of Nitrosospira-related AOB and Nitrososphaera-related AOA varied across the latitudinal gradient. Variance partitioning analysis showed that geography and climatic conditions (e.g., mean annual temperature and precipitation), as well as carbon-/nitrogen-related soil nutrients, contributed more to the AOB and AOA community variations (∼50% in total) than soil pH (∼10% in total). These results are important in furthering our understanding of environmental conditions influencing AOB and AOA community structure across a range of environmental gradients.

Correlation of seasonal nitrification failure and ammonia-oxidizing community dynamics in a wastewater treatment plant treating water from a saline thermal spa

In this work we evaluated the effect of a perturbation on nitrification performance in a wastewater treatment plant (WWTP) treating urban and saline thermal bath wastewater, which regularly occurred during summer months. We wanted to find out if this related to changes in the ammonia oxidizing communities. The bacterial and ammonia-oxidizing bacterial (AOB) community from three different basins of the WWTP were evaluated using PCR-DGGE and cloning and sequencing of 16S rRNA gene fragments, over a six month survey. Both eubacterial and AOB communities underwent continuous change over time, with a particularly prominent shift between the third and fourth month of monitoring for eubacteria and the fourth month and fifth month for AOB. At the same time, reduction of nitrification performance was observed in the WWTP. The AOB community in the activated sludge was dominated by clones with high 16S rRNA sequence identity to halophilic-halotolerant organisms from the Nitrosomonas oligotrohpa and Nitrosomonas marina clusters. A significant correlation (R = 0.97) was detected between the structure of the AOB community and environmental parameters, indicating that the AOB community structure changed in line with the environmental changes that took place over the sampling period. This study reports a clear association of microbial community dynamics (strongly correlated to salinity, temperature, and dissolved oxygen) to nitrification performance. Particularly, ammonia-oxidizing bacteria are severely affected by drastic changes in operational conditions, with direct consequences on WWTP performance.

Impact of sheep urine deposition and plant species on ammonia-oxidizing bacteria in upland grassland soil

The effects of different concentrations of synthetic sheep urine and plant species on ammonia-oxidizing bacterial (AOB) communities in an upland grassland soil were investigated using a microcosm approach. Plant species characteristic of unimproved and improved agricultural pastures (Agrostis capillaris and Lolium perenne, respectively) were planted in soil microcosms, and different levels of synthetic sheep urine were applied, with harvests 10 and 50 days following urine application. Shifts in the community structure of the AOB were investigated using terminal restriction fragment length polymorphism of amoA amplicons. Species richness and diversity were significantly altered by synthetic sheep urine addition and time depending on plant species type. Principal coordinate analysis revealed that AOB community structure was largely dependent on interactions between sheep urine deposition, plant species, and time after urine application, while significant changes in AOB structure were also revealed by similarity percentage analysis. The results of this study suggested that high levels of sheep urine, combined with floristic changes that are characteristic of agricultural intensification, can contribute to temporal and spatial changes in the structure of key bacterial communities in upland grassland soil. Changes in AOB community structure could potentially affect important soil processes, such as nitrification, with subsequent implications for nutrient cycling in agricultural systems.

Population Dynamics of the Ammonia-Oxidizing Bacteria in a Full-Scale Municipal Wastewater Treatment Facility

The purpose of this study was to examine the ammonia oxidizing bacterial (AOB) communities from a full-scale municipal wastewater treatment plant, and to relate these analyses to treatment efficiency. Although almost complete nitrification was observed for extended periods of the year, nitrification efficiency decreased to about 60–80% during December through March. Substantial changes in the AOB community structure were detected using a nested PCR-DGGE approach. Quantification of Nitrosomonas oligotropha- like bacterial populations by competitive quantitative PCR targeting amoA gene fragments revealed that these populations varied more than eightfold throughout the year. Statistical analysis revealed a weak correlation between the quantity of N. oligotropha-like populations and nitrification efficiency, suggesting that these quantification of these bacteria would be useful for monitoring nitrification in wastewater treatment bioreactors.

Spatiotemporal Stability of an Ammonia-Oxidizing Community in a Nitrogen-Saturated Forest Soil.

Elevated levels of nitrogen input into various terrestrial environments in recent decades have led to increases in soil nitrate production and leaching. However, nitrifying potential and nitrifying activity tend to be highly variable over space and time, making broad-scale estimates of nitrate production difficult. This study investigates whether the high spatiotemporal variation in nitrate production might be explained by differences in the structure of ammonia-oxidizing bacterial communities in nitrogen-saturated coniferous forest soils. The diversity of ammonia-oxidizing bacteria of the b-subgroup Proteobacteria was therefore investigated using two different PCR-based approaches. The first targeted the 16S rRNA gene and involved temporal temperature gradient electrophoresis (TTGE) of specifically amplified PCR products, with subsequent band excision and nucleotide sequence determination. The second approach involved the cloning and sequencing of PCR-amplified amoA gene fragments. All recovered 16S rDNA sequences were closely related to the culture strain Nitrosospira sp. AHB1, which was isolated from an acid soil and is affiliated with Nitrosospira cluster 2, a sequence group previously shown to be associated with acid environments. All amoA-like sequences also showed a close affinity with this acid-tolerant Nitrosospira strain, although greater sequence variation could be detected in the amoA analysis. The ammonia-oxidizing bacterial community in the nitrogen-saturated coniferous forest soil was determined to be very stable, showing little variation between different organic layers and throughout the year, despite large differences in the total Bacterial community structure as determined by 16S rDNA DGGE community fingerprinting. These results suggest that environmental heterogeneity affecting ammonia oxidizer numbers and activity, and not ammonia oxidizer community structure, is chiefly responsible for spatial and temporal variation in nitrate production in these acid forest soils.