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Pond aquaculture is an important aquacultural model worldwide in which ammonia-oxidizing bacteria (AOB) are crucial for the removal of ammonia from water. The influence of light irradiation on AOB in an aquaculture pond was studied using artificial simulation wastewater under dark/light cycles of 24 h/0 h (L0), 12 h/12 h (L12), and 0 h/24 h (L24). The ammonia oxidation rates (AORs) in groups L0, L12, and L24 were 9.88 ± 0.19 mg h−1, 6.01 ± 0.32 mg h−1, and 1.85 ± 0.09 mg h−1, respectively. Long-term exposure to light had a serious impact on the AOR and decreased the abundance of Nitrosomonas spp. and their ammonia monooxygenase genes. To determine the protective effect of microalgae on AOB, different doses of freeze-dried Chlorella spp. powder were added to the nitrifying bacteria community. The photoinhibition rate of chlorophyll a (Chla) in the groups with 300 and 1300 µg L−1 of added Chlorella were 32.85% and 28.77%, respectively, while the Chla in the 2200 µg L−1 Chlorella-added group was only 0.01%, with no significant differences (p > 0.05) in AOR between the dark/light treatment subgroups. Fluorescence in situ hybridization showed that AOB, nitrite-oxidizing bacteria, and algae coexist and grow together without free AOB in the nitrifying bacterial community. It was suggested that microalgae enhance the resistance of AOB to light irradiation in a pond through the shading effect provided by algal chlorophyll and the close symbiotic relationship between microalgae and AOB. [ABSTRACT FROM AUTHOR]

Elevated CO2 levels (eCO2) pose challenges to wheat (Triticum aestivum L.) growth, potentially leading to a decline in quality and productivity. This study addresses the effects of two ambient CO2 concentrations (aCO2, daytime/nighttime = 410/450 ± 30 ppm and eCO2, 550/600 ± 30 ppm) and two nitrogen (N) supplements (without N supply—N0 and with 100 mg N supply as urea per kg soil—N100) on wheat (T. aestivum cv. Yunmai) growth, N accumulation, and soil microbial communities related to ammonia oxidization. The data showed that the N supply effectively mitigated the negative impacts of eCO2 on wheat growth by reducing intercellular CO2 concentrations while enhancing photosynthesis parameters. Notably, the N supply significantly increased N concentrations in wheat tissues and biomass production, thereby boosting N accumulation in seeds, shoots, and roots. eCO2 increased the agronomic efficiency of applied N (AEN) and the physiological efficiency of applied N (PEN) under N supply. Plant tissue N concentrations and accumulations are positively related to plant biomass production and soil NO3−-N. Additionally, the N supply increased the richness and evenness of the soil microbial community, particularly Nitrososphaeraceae, Nitrosospira, and Nitrosomonas, which responded differently to N availability under both aCO2 and eCO2. These results underscore the importance and complexity of optimizing N supply and eCO2 for enhancing crop tissue N accumulation and yield production as well as activating nitrification-related microbial activities for soil inorganic N availability under future global environment change scenarios. [ABSTRACT FROM AUTHOR]

Elevated CO2 levels (eCO2) pose challenges to wheat (Triticum aestivum L.) growth, potentially leading to a decline in quality and productivity. This study addresses the effects of two ambient CO2 concentrations (aCO2, daytime/nighttime = 410/450 ± 30 ppm and eCO2, 550/600 ± 30 ppm) and two nitrogen (N) supplements (without N supply—N0 and with 100 mg N supply as urea per kg soil—N100) on wheat (T. aestivum cv. Yunmai) growth, N accumulation, and soil microbial communities related to ammonia oxidization. The data showed that the N supply effectively mitigated the negative impacts of eCO2 on wheat growth by reducing intercellular CO2 concentrations while enhancing photosynthesis parameters. Notably, the N supply significantly increased N concentrations in wheat tissues and biomass production, thereby boosting N accumulation in seeds, shoots, and roots. eCO2 increased the agronomic efficiency of applied N (AEN) and the physiological efficiency of applied N (PEN) under N supply. Plant tissue N concentrations and accumulations are positively related to plant biomass production and soil NO3−-N. Additionally, the N supply increased the richness and evenness of the soil microbial community, particularly Nitrososphaeraceae, Nitrosospira, and Nitrosomonas, which responded differently to N availability under both aCO2 and eCO2. These results underscore the importance and complexity of optimizing N supply and eCO2 for enhancing crop tissue N accumulation and yield production as well as activating nitrification-related microbial activities for soil inorganic N availability under future global environment change scenarios.

In this study, we evaluated the biotransformation mechanisms of lincomycin (LIN) and three fluoroquinolone antibiotics (FQs), ciprofloxacin (CFX), norfloxacin (NFX), and ofloxacin (OFX), which regularly enter aquatic environments through human activities, by different ammonia-oxidizing microorganisms (AOM). The organisms included a pure culture of the complete ammonia oxidizer (comammox) Nitrospira inopinata, an ammonia oxidizing archaeon (AOA) Nitrososphaera gargensis, and an ammonia-oxidizing bacterium (AOB) Nitrosomonas nitrosa Nm90. The removal of these antibiotics by the pure microbial cultures and the protein-normalized biotransformation rate constants indicated that LIN was significantly co-metabolically biotransformed by AOA and comammox, but not by AOB. CFX and NFX were significantly co-metabolized by AOA and AOB, but not by comammox. None of the tested cultures transformed OFX effectively. Generally, AOA showed the best biotransformation capability for LIN and FQs, followed by comammox and AOB. The transformation products and their related biotransformation mechanisms were also elucidated. i) The AOA performed hydroxylation, S-oxidation, and demethylation of LIN, as well as nitrosation and cleavage of the piperazine moiety of CFX and NFX; ii) the AOB utilized nitrosation to biotransform CFX and NFX; and iii) the comammox carried out hydroxylation, demethylation, and demethylthioation of LIN. Hydroxylamine, an intermediate of ammonia oxidation, chemically reacted with LIN and the selected FQs, with removals exceeding 90%. Collectively, these findings provide important fundamental insights into the roles of different ammonia oxidizers and their intermediates on LIN and FQ biotransformation in nitrifying environments including wastewater treatment systems.

This study was conducted to determine the bacterial composition and its effect on Artemia performance in various Artemia biomass culture conditions. Newly hatched Artemia franciscana were cultured in 1.5L plastic bottles containing 1L of culture medium, with a density of 200 nauplii/L and salinity 30 ppt, and lasted for three weeks. In the first two days after stocking, Artemia was fed with Chaetoceros sp. Afterward, Artemia-formulated feed was used as daily food. In biofloc and bacteria treatments, the C/N ratio was regularly manipulated in the Artemia culture medium from day 5 and onwards. The statistical analysis results showed that culture conditions, as well as the bacterial development in those culture batches, affected Artemia performance. The best survival rate, individual length, and biomass were obtained in the seawater and biofloc treatment after 21 days of culturing. The total bacteria varied from 83-146 × 103 CFU/mL, with the highest value seen in the biofloc (BF) treatments. The biofloc treatments had a significantly higher bacterial density than the nonbiofloc treatments. Nitrosomonas was better developed in seawater (SW) while the Nitrobacter was in sea salt (SS) medium. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Obtaining efficient autotrophic ammonia removal (aka partial nitritation-anammox, or PNA) requires a balanced microbiome with abundant aerobic and anaerobic ammonia oxidizing bacteria and scarce nitrite oxidizing bacteria. Here, we analyzed the microbiome of an efficient PNA process that was obtained by sequential feeding and periodic aeration. The genomes of the dominant community members were inferred from metagenomes obtained over a 6 month period. Three Brocadia spp. genomes and three Nitrosomonas spp. genomes dominated the autotrophic community; no NOB genomes were retrieved. Two of the Brocadia spp. genomes lacked the genomic potential for nitrite reduction. A diverse set of heterotrophic genomes was retrieved, each with genomic potential for only a fraction of the denitrification pathway. A mutual dependency in amino acid and vitamin synthesis was noted between autotrophic and heterotrophic community members. Our analysis suggests a highly-reticulated nitrogen cycle in the examined PNA microbiome with nitric oxide exchange between the heterotrophs and the anammox guild.

Quick-start nitrifying products (QSNP) are sold to aquarium hobbyists with the claim that the nitrogen cycle is rapidly initiated allowing for instant addition of fish. Despite these claims, none of these products have been the subject of peer-reviewed evaluation. Six 10-gallon aquaria were used to simulate a naïve fresh water system. Water temperature, pH and dissolved oxygen were measured to ensure stability between aquaria. On Day 0, 1.0-ppm ammonium hydroxide was added to each of the aquaria. Five aquaria received a different QSNP on Day 1 of the study. One aquarium acted as a control, receiving no QSNP. Total ammonia nitrogen (TAN), nitrite and nitrate levels were monitored every 48-hours for 14 days. Total ammonia nitrogen concentrations were significantly lower in the Tetra samples compared to all other samples and controls (all P < 0.001). Additionally, TAN concentrations were significantly lower on days 4 to 14 compared to baseline (all P < 0.001). There were no significant differences in nitrite concentrations by treatment (F = 1.3, P = 0.263) or time (F = 1.0, P = 0.416). Nitrate concentrations were significantly higher in the Cycle (P < 0.001) and Tetra (P = 0.001) samples compared to the control samples. Nitrate concentrations were also found to be significantly higher on days 4 (P = 0.027), 10 (P = 0.041), 12 (P = 0.011), and 14 (P = 0.007) compared to baseline. Four out of 5 QSNP failed to reduce TAN concentrations from baseline levels over the 14-day test period. One of the QSNP appears to significantly be able to reduce TAN concentrations in controlled freshwater aquaria. Quick-start nitrifying products should not be recommended as a sole method when initiating the nitrogen cycle in fresh water aquaria until further studies have evaluated these products. [ABSTRACT FROM AUTHOR]

• The dominant AOB was Nitrosomonas in dynamic acidic pH. • AOB activity in the weak acidic zone reached 14.5 ± 2.6 mg N L −1 h −1. • Nitrospira is extremely tolerant to FNA with the half-saturation inhibition constant of 0.37 ± 0.10 mg HNO 2 N/L. • Maximum FNA of 6.5 HNO 2 N/L in dynamic acidic pH could effectively inhibit and inactivate NOB activity. • Endpoint pH and exposure time were critical for high-rate stable acidic partial nitritation. How to intensify the ammonia oxidation rate (AOR) is still a bottleneck impeding the technology development for the innovative acidic partial nitritation because the eosinophilic ammonia-oxidizing bacteria (AOB), such as Nitrosoglobus or Nitrosospira , were inhibited by the high-level free nitrous acid (FNA) accumulation in acidic environments. In this study, an innovative approach of dynamic acidic pH regulation control strategy was proposed to realize high-rate acidic partial nitritation driven by common AOB genus Nitrosomonas. The acidic partial nitrification process was carried out in a laboratory-scale sequencing batch moving bed biofilm reactor (SBMBBR) for long-term (700 days) to track the effect of dynamic acidic pH on nitrifying bacterial activity. The results indicated that the influent NH 4 +-N concentration was about 100 mg/L, the nitrite accumulation ratio was exceeding 90%, and the maximum AOR can reach 14.5 ± 2.6 mg N L −1 h −1. Although the half-saturation inhibition constant of NOB (K I_FNA(AOB)) reached 0.37 ± 0.10 mg HNO 2 N/L and showed extreme adaptability in FNA, the inactivation effect of FNA (6.1 mg HNO 2 N/L) for NOB was much greater than that of AOB, with inactivation rates of 0.61 ± 0.08 h −1 and 0.06 ± 0.01 h −1, respectively. The effluent pH was gradually reduced to 4.5 by ammonia oxidation process and the periodic FNA concentration reached 6.5 mg HNO 2 N/L to inactivate nitrite-oxidizing bacteria (NOB) without negatively affecting Nitrosomonas during long-term operation. This result provides new insights for the future implementation of high-rate stabilized acidic partial nitritation by Nitrosomonas. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The N 2 O comes from denitrification of nitrite produced by nitrification in composting. • Nitrosomonas carrying amoA and nirK participate in nitrification and denitrification. • Dicyandiamide delayed N 2 O emissions for through delayed nitrification in mature phase. • Dicyandiamide increases the N 2 O produced by amoA dominated incomplete nitrification. • 10% dicyandiamide reduces N 2 O production of denitrification by inhibiting hao and nitrite. Nitrous oxide (N 2 O) emissions contribute to nitrogen loss and exacerbate the greenhouse effect during composting. Investigating the efficacy and underlying mechanisms of dicyandiamide (DCD) in reducing N 2 O emissions can inform composting strategies aimed at mitigating global climate change. In this study, 5 % or 10 % DCD (based on TN content in the initial mixture) was added during the maturation phase of composting, resulting in delayed N 2 O production. In the control (CK) treatment without DCD, N 2 O production primarily stemmed from denitrification, facilitated by ammonia-oxidizing bacteria (AOB) providing nitrite substrate. The DCD-treated groups exhibited prolonged NH 4 + retention times, and the significant N 2 O emissions were postponed by 4–9 days instead of being consistently inhibited. Notably, the Nitrosomonas genus emerged as the primary AOB contributing to N 2 O emissions, engaging in both nitrification and nitrifier denitrification processes, particularly through Nitrosomonas europaea carrying the nirK gene. DCD delayed nitrification via the amoA gene and persistently hindered the enrichment of hao genes. With a 10 % DCD addition, the predominant pathway for N 2 O production shifted from denitrification, dominated by nirK and norB genes, to incomplete nitrification, predominantly influenced by Nitrosomonas carrying the amoA gene. This study offers a novel perspective on elucidating the mechanism by which DCD influences N 2 O production in composting. [ABSTRACT FROM AUTHOR]

A betaproteobacterial chemolithotrophic ammonia-oxidizing bacterium designated APG5T was isolated from supralittoral sand of the Edmonds City Beach, WA, USA. Growth was observed at 10–35 °C (optimum, 30 °C), pH 5–9 (optimum, pH 8) and ammonia concentrations as high as 100 mM (optimum, 1–30 mM NH4Cl). The strain grows optimally in a freshwater medium but tolerates up to 400 mM NaCl. It is most closely related to ‘Nitrosomonas ureae’ (96.7% 16S rRNA and 92.4% amoA sequence identity). The 3.75-Mbp of AGP5T draft genome contained a single rRNA operon and all necessary tRNA genes and has the lowest G+C content (43.5%) when compared to the previously reported genomes of reference strains in cluster 6 Nitrosomonas. Based on an average nucleotide identity of 82% with its closest relative (‘N. ureae’ Nm10T) and the suggested species boundary of 95–96%, a new species Nitrosomonas supralitoralis sp. nov. is proposed. The type strain of Nitrosomonas supralitoralis is APG5T (= NCIMB 14870T = ATCC TSD-116T). [ABSTRACT FROM AUTHOR]

Obtaining efficient autotrophic ammonia removal (aka partial nitritation-anammox, or PNA) requires a balanced microbiome with abundant aerobic and anaerobic ammonia oxidizing bacteria and scarce nitrite oxidizing bacteria. Here, we analyzed the microbiome of an efficient PNA process that was obtained by sequential feeding and periodic aeration. The genomes of the dominant community members were inferred from metagenomes obtained over a 6 month period. Three Brocadia spp. genomes and three Nitrosomonas spp. genomes dominated the autotrophic community; no NOB genomes were retrieved. Two of the Brocadia spp. genomes lacked the genomic potential for nitrite reduction. A diverse set of heterotrophic genomes was retrieved, each with genomic potential for only a fraction of the denitrification pathway. A mutual dependency in amino acid and vitamin synthesis was noted between autotrophic and heterotrophic community members. Our analysis suggests a highly-reticulated nitrogen cycle in the examined PNA microbiome with nitric oxide exchange between the heterotrophs and the anammox guild. [ABSTRACT FROM AUTHOR]

• Bacterial ammonia monooxygenase genes and host were decreased after COVID-19 exposure. • The disturbance of ammonia oxidation recovered in the post-pandemic period. • Disinfectants destroy cell structure and cause oxidative stress of Nitrosomonas. • Sodium hypochlorite induce the downregulation of ammonia monooxygenase genes. • Sodium hypochlorite destroy the structure of ammonia monooxygenase protein. Anthropogenic activities significantly impact the elemental cycles in aquatic ecosystems, with the N-cycling playing a critical role in potential nutrient turnover and substance cycling. We hypothesized that measures to prevent COVID-19 transmission profoundly altered the nitrogen cycle in riverine ecosystems. To investigate this, we re-analyzed metagenomic data and identified 60 N-cycling genes and 21 host metagenomes from four urban reaches (one upstream city, Wuhan, and two downstream cities) along the Yangtze River. Our analyses revealed a marked decrease in the abundance of bacterial ammonia monooxygenase genes, as well as in the host, ammonia-oxidizing autotrophic Nitrosomonas , followed by a substantial recovery post-pandemic. We posited that discharge of sodium hypochlorite (NaOCl) disinfectant may be a primary factor in the reduction of N-cycling process. To test this hypothesis, we exposed pure cultures of Nitrosomonas europaea to NaOCl to explore the microbial stress response. Results indicated that NaOCl exposure rapidly compromised the cell structure and inhibited ammonia oxidation of N. europaea , likely due to oxidative stress damage and reduced expression of nitrogen metabolism-related ammonia monooxygenase. Using the functional tagging technique, we determined that NaOCl directly destroyed the ammonia monooxygenase protein and DNA structure. This study highlights the negative impacts of chlorine disinfectants on the function of aquatic ecosystems and elucidates potential mechanisms of action. [Display omitted] [ABSTRACT FROM AUTHOR]

Nitrogen (N) stabilizer containing nitrapyrin inhibitor is responsible for slowing the activity of Niirosomonas sp. bacteria down which oxidize ammonium to nitrite ions, thus, N-loss resulting from nitrate leaching can be reduced. Although prior studies have shown its effectiveness in the pre-sowing application in maize, considering that it disturbs the activity of Nitrosomonas bacteria which is the most intense between 25 °C and 30 °C, soil temperature may significantly influence the efficiency of nitrapyrin. Besides, nitrapyrin aims to enhance N-use efficiency in high N-demanding plants, such as maize, which demands N at the most during stalk elongation, which lays down the reason for its subsequent application. This study focuses on the efficiency of nitrapyrin at different soil temperatures and its impacts on the physiological development and productivity of maize. In a laboratory test, 10 °C, 15 °C, 20 °C, and 25 °C temperature soils were treated with nitrapyrin and change of nitrate content was monitored to observe the nitrification dynamic. Results show that as the soil temperature elevated, the inhibition efficiency increased. In a field experiment with maize, nitrapyrin was applied in 13 °C and 25 °C temperature soil. Results suggest the later treatment enhanced N-use efficiency, as, during the high N-demanding growth stage, more N-forms were available in the soil. This resulted in significantly higher relative chlorophyll concentration in the leaves and laboratory leaf analysis confirmed the prevention of N deficiency. Results of further measurements on parameters indicating biomass production such as root mass, stalk diameter, ear size, 1,000-kemel weight indicate that the nitrapyrin application should be timed later. [ABSTRACT FROM AUTHOR]

Aims: Ammonia oxidation is a significant process of nitrogen cycles in a lot of ecosystems sediments while there are few studies in shrimp culture pond (SCP) sediments. This paper attempted to explore the community diversity and abundance of ammonia‐oxidizing archaea (AOA) and ammonia‐oxidizing bacteria (AOB) in SCP sediments at different culture stages. Methods and Results: We collected SCP sediments and analysed the community diversity and abundance of AOA and bacteria in shrimp pond sediment at different culture stages using the ammonia monooxygenase (amoA) gene with quantitative PCR (qPCR) and 16S rRNA gene sequencing. The AOB‐amoA gene abundance was showed higher than AOA‐amoA gene abundance in SCP sediments on Day 50 and Day 60 after shrimp larvae introducing into the pond, and the diversity of AOA in SCP sediments was higher than that of AOB. The phylogenetic tree revealed that the most of AOA were the member of Nitrosopumilus and Nitrososphaera, and the majority of AOB sequences were clustered into Nitrosospira, Nitrosomonas clusters 6a and 7. The AOA community has close relationship with total organic carbon (TOC), pH, total phosphorus (TP), nitrate reductase, urease, acid phosphatase and β‐glucosidase. The AOB community was related to TOC, C/N and nitrate reductase. Conclusions: AOA and AOB play the different ecological roles in SCP sediments at different culture stages. Significance and Impact of the Study: Our results suggested that the different community diversity and abundance of AOA and AOB in SCP sediments, which may improve our ecological cognition of shrimp culture stages in SCP ecosystems. [ABSTRACT FROM AUTHOR]

The belowground soil environment is an active space for microbes, particularly Arbuscular Mycorrhizal Fungi (AMF) and P hosphate Solubilizing Bacteria (PSB) that can colonize with roots of higher plants. In the present experiment, we evaluated the combination of microbial inoculants with the different doses of urea and superphosphate in a complete randomized block design (CRBD). Three different doses of urea and superphosphate were tested, i.e., recommended dose, 75% of the recommended dose and 125% of the recommended dose, independently and in combination with three microbial groups viz. Glomus mosseae (AMF), Bacillus subtilis (PSB) and Nitrifying microorganisms (Nitrosomonas + Nitrobacter , NN). Overall, there were 16 treatment combinations used, and studied the number of tubers per plant, the weight of tubers, moisture content, and the number of nodes per tubers which were best in treatment comprising of AMF + PSB + NN + 75% of urea + superphosphate. From our results, it is suggested for the growers to use a lesser quantity of fertilizers from the recommended dose along with some bioinoculants to maintain the soil fertility and also to achieve the yield targets by decreasing the cost of chemical fertilizers. [ABSTRACT FROM AUTHOR]

Nitrogen species such as ammonia and nitrite are considered as major stressors in modern aquaculture practices. We developed enrichments of ammonia oxidising bacteria (AOB) and nitrite oxidising bacteria (NOB) for effective mitigation of nitrogenous wastes in the shrimp culture operations. The objective of this study was to understand the microbial community composition of AOB and NOB enrichments using the V3-V4 region of the 16S rDNA gene by Illumina MiSeq sequencing. The analysis revealed 2948 and 1069 OTUs at 97% similarity index and Shannon alpha diversity index of 7.64 and 4.85 for AOB and NOB enrichments, respectively. Comparative analysis showed that a total of 887 OTUs were common among AOB and NOB enrichments. The AOB and NOB enrichment were dominated by Eubacteria at 96% and 99.7% respectively. Proteobacterial phylum constituted 31.46% (AOB) and 39.75% (NOB) and dominated by α-Proteobacteria (20%) in AOB and γ-Proteobacteria (16%) in NOB. Among the species in AOB enrichment (2,948) two sequences were assigned to ammonia oxidising bacterial group belonging to Nitrosomonas, and Nitrosococcus genera and two belonged to archaeon group comprising Nitrosopumilus and Candidatus Nitrososphaeraea genera. The NOB enrichment was predominated by Nitrospiraceae and Thermodesulfovibrionaceae. Further, the data revealed the presence of heterotrophic bacteria contributing to the process of nitrification and form microcosm with the AOB and NOB. PICRUSt analysis predicted the presence of 24 different nitrogen cycling genes involved in nitrification, denitrification, ammonia and nitrogen transporter family, nitrate reduction and ammonia assimilation. The study confirms the presence of many lesser known nitrifying bacteria along with well characterised nitrifiers. [ABSTRACT FROM AUTHOR]

To understand the effects of biochar and urea on soil N availability and plant growth, we conducted a pot experiment growing barley (Hordeum vulgare L.) under six treatments: control (N0), soil with 30 g kg−1 biochar (N0B), soil with 0.23 g kg−1 urea (N1), soil with 0.23 g kg−1 urea and 30 g kg−1 biochar (N1B), soil with 0.46 g kg−1 urea (N2), and soil with 0.46 g kg−1 urea and 30 g kg−1 biochar (N2B). The nitrifying community abundance and compositions in rhizosphere and bulk soils were analyzed using quantitative polymerase chain reaction (qPCR) and amplicon-based Illumina Hiseq sequencing. Adding urea with biochar (N1B) produced the greatest increase in above- and belowground plant biomass, followed by doubling the amount of urea with biochar (N2B); both treatments raised pH (p < 0.001) and lowered extractable N in the rhizosphere (p < 0.05). N1B treatment produced the greatest increase in ammonia-oxidizing bacteria (AOB) amoA gene copies, presumably because the combined amendment raised soil pH, which favored AOB access to NH4+. Nitrifier sequences were selected after blasting with reported nitrifiers in NCBI (similarity ≥ 97%). Nitrosospira dominated AOB communities during the plant seedling stage; however, during the mature stage, Nitrosomonas dominated over Nitrosospira and the nitrite-oxidizing bacteria (NOB) community became diverse. Redundancy analysis indicated that nitrifying community composition was affected by multiple soil properties, including N availability (i.e., exchangeable NH4+ and NO3−) and soil chemistry (i.e., pH, dissolved organic C, and exchangeable base cations). Our research suggests a positive application of combining biochar with urea in improving N bioavailability and promoting plant growth in the acidic soil. [ABSTRACT FROM AUTHOR]

Copyright of Environmental Science & Technology (10036504) is the property of Editorial Board of Environmental Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The biological oxidation of ammonia (i.e. nitrification), results in the transformation of relatively immobile NH4+ into a highly mobile NO3-, which is vulnerable to losses through leaching and denitrification, resulting in low nitrogen-use efficiency in agricultural systems. The ability of certain plants to suppress soil nitrifier function by releasing inhibitors from roots is termed 'biological nitrification inhibition' (BNI). Using a recombinant luminescent Nitrosomonas europaea, we developed an assay to detect and quantify the inhibitory effects in plant soil systems termed, 'BNI activity', expressed in ATU (allylthiourea unit). Sorghum roots released (into water-based medium, hereafter referred to as root exudates) substantial amount of BNI activity. The BNI capacity (ATU g-1 root dry wt d-1) of roots changed with growth stage, from 60 ATU at 3 week old to 20 ATU at 45 day stage. In addition, sorghum roots released hydrophobic compounds, which can be recovered by washing with dichloromethane (hereafter referred to as DCM-root wash). One of the active constituents with BNI activity in root exudates, isolated by activity-guided HPLC fractionation, was a flavonoid, identified as sakuranetin. Using a similar approach, the major active constituent with BNI activity in DCM-root wash was isolated and identified as sorgoleone. Both sakuranetin and sorgoleone inhibited Nitrosomonas activity in a dose-response manner. Substantial genetic variability for sorgoleone production capacity was detected in sorghum. Some wild-sorghum species showed high-BNI capacity under field conditions. Potential implications of BNI in inhibiting nitrification and in reducing the nitrogen footprint from agricultural systems will be discussed.

This study investigated the effect of high DO concentrations on PN. The experimental setup involved operating at high DO concentrations (1.5–2.5 mg/L) and environmental temperatures (15–20 °C) over a period of 180 days. Through a sludge enrichment process, the kinetic parameters of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were determined. Surprisingly, contrary to conventional reports, it was observed that NOB exhibited a stronger affinity for DO compared to AOB. As a result, high DO concentrations were necessary to provide favorable conditions for the growth of AOB. In order to establish PN, strategies including intermittent aeration, free ammonia (FA), and controlled sludge retention time (SRT) were employed. The successful PN was achieved with a specific ammonia oxidation rate of 24 mg N/g MLVSS/h and a specific nitrite oxidation rate below 0.10 mg N/g MLVSS/h. The nitrite accumulation rate (NAR) was maintained at 100% during stable operation. The abundance of Nitrosomonas, a typical genus of AOB, was found to be 68.62%, which surpasses previous studies in similar research. A slightly higher DO concentrations may increase energy consumption, but achieve higher efficiency and stability in PN. This study provided new insights into the application of PN in wastewater treatment. [Display omitted] • The affinity of NOB for DO was stronger than that of AOB after enrichment culture. • Nitrosomonas was the dominant genus in the PN stable state with 68.62% abundance. • Nitrite accumulation rate was 100%. • The activity of AOB (24 mg N/g MLVSS/h) was much greater than that of NOB (<0.1 mg N/g MLVSS/h) in the PN stable state. [ABSTRACT FROM AUTHOR]

The study aimed at understanding the competitive ability of legumes Vigna radiata L. and Mucuna pruriens with weeds and their effects on the activity of nitrifying bacteria in soils and the contents of organic-N in legumes and weeds. The experiment was arranged in a randomized block design with three factors and four replications. The first factor was soil order, i.e. Inceptisol and Vertisol; the second factor was types of legumes, i.e. Vigna radiata L. cultivar Sriti and Mucuna pruriens; and the third factor was weed management, i.e. with weed management and without weed management. The results showed that Vigna radiata L. and Mucuna pruriens indirectly influence the supply of available nitrogen in soils that can be taken up by the coexisted plants or weeds via the inhibition of the growth of Nitrosomonas and Nitrobacter in soils. As a results, the organic-N content in weeds decreases, which is in contrast to the increasing amount of organic-N in Vigna radiata L. and Mucuna pruriens. The results indicated that Vigna radiata L. and Mucuna pruriens are considered as allelophatic legumes, resulting in low organic-N content in weeds.

With the increasing complexity of influent composition in wastewater treatment plants, the potential stimulating effects of refractory organic matter in wastewater on growth characteristics and genera conversion of nitrifying bacteria (ammonium-oxidizing bacteria [AOB] and nitrite-oxidizing bacteria [NOB]) need to be further investigated. In this study, domestic wastewater was co-treated with landfill leachate in the lab-scale reactor, and the competition and co-existence of NOB genera Nitrotoga and Nitrospira were observed. The results demonstrated that the addition of landfill leachate could induce the growth of Nitrotoga, whereas Nitrotoga populations remain less competitive in domestic wastewater operation. In addition, the refractory organic matter in the landfill leachate also would have a potential stimulating effect on the maximum specific growth rate of AOB genus Nitrosomonas (μ max, aob ). The μ max, aob of Nitrosomonas in the control group was estimated to be 0.49 d -1 by fitting the ASM model, and the μ max, aob reached 0.66-0.71 d -1 after injection of refractory organic matter in the landfill leachate, while the maximum specific growth rate of NOB (μ max, nob ) was always in the range of 1.05-1.13 d -1 . These findings have positive significance for the understanding of potential stimulation on nitrification processes and the stable operation of innovative wastewater treatment process., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Ammonia-oxidizing bacteria, key players in the nitrogen cycle, have been the focus of extensive research. Numerous novel species have been isolated and their growth dynamics were studied. Despite these efforts, controlling their growth to obtain diverse physiological findings remains a challenge. These bacteria often fail to grow, even under optimal conditions. This unpredictable growth pattern could be viewed as a survival strategy. Understanding this heterogeneous behavior could enhance our ability to culture these bacteria. In this study, the variation in the growth rate was quantified for the ammonia-oxidizing bacterium Nitrosomonas mobilis Ms1. Our findings revealed significant growth rate variation under low inoculum conditions. Interestingly, higher cell densities resulted in more stable cultures. A comparative analysis of three Nitrosomonas species showed a correlation between growth rate variation and culture failure. The greater the variation in growth rate, the higher the likelihood of culture failure., (© The Author(s) 2024. Published by Oxford University Press on behalf of FEMS.)

Ammonia-oxidizing bacteria (AOB) within the genus Nitrosomonas perform the first step in nitrification, ammonia oxidation, and are found in diverse aquatic and terrestrial environments. Nitrosomonas AOB were grouped into six defined clusters, which correlate with physiological characteristics that contribute to adaptations to a variety of abiotic environmental factors. A fundamental physiological trait differentiating Nitrosomonas AOB is the adaptation to either low (cluster 6a) or high (cluster 7) ammonium concentrations. Here, we present physiological growth studies and genome analysis of Nitrosomonas cluster 6a and 7 AOB. Cluster 6a AOB displayed maximum growth rates at ≤ 1 mM ammonium, while cluster 7 AOB had maximum growth rates at ≥ 5 mM ammonium. In addition, cluster 7 AOB were more tolerant of high initial ammonium and nitrite concentrations than cluster 6a AOB. Cluster 6a AOB were completely inhibited by an initial nitrite concentration of 5 mM. Genomic comparisons were used to link genomic traits to observed physiological adaptations. Cluster 7 AOB encode a suite of genes related to nitrogen oxide detoxification and multiple terminal oxidases, which are absent in cluster 6a AOB. Cluster 6a AOB possess two distinct forms of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) and select species encode genes for hydrogen or urea utilization. Several, but not all, cluster 6a AOB can utilize urea as a source of ammonium. Hence, although Nitrosomonas cluster 6a and 7 AOB have the capacity to fulfill the same functional role in microbial communities, i.e., ammonia oxidation, differentiating species-specific and cluster-conserved adaptations is crucial in understanding how AOB community succession can affect overall ecosystem function. [ABSTRACT FROM AUTHOR]

In this study, partial-nitrification and anammox biomass were co-immobilized by polyvinyl alcohol and sodium alginate (PVA-SA) to treat the ammonium-rich wastewater. The enriched partial nitrification and anammox sludge entrapped in the beads. The beads were round in shape with 4-5 mm in diameter and not agglomerated with each other. The ammonium removal efficiency of 80% achieved within ten days. The nitrogen loading rate varied from the start (37 mg/L/d) to the end of experiment (75 mg/L/d). The enriched sludge, suitable environment inside of the beads for growth of bacteria, and low diffusion constraints were the possible reasons for the fast start-up of PN-anammox system. The necrosis/apoptosis analysis confirmed that there was no observed death phenomena inside of the gel beads in a normal operation of the reactor. The microbial community analysis showed that the dominance of phyla Proteobacteria (35.35%) while the abundance of phyla Planctomycetes was 2.42%. Likewise, at the genus level, Candidatus Brocadia accounts for 1.33% while Nitrosomonas was 0.89%, but the highest shared observed from the genus Burkholderia. The use of immobilization technology in the application of the SNAP process may represent a valuable alternative to other technologies such as granulation, suspended cell growth and biofilm system. [ABSTRACT FROM AUTHOR]

Ammonia emission during composting results in anthropogenic odor nuisance and reduces the agronomic value of the compost due to the loss of nitrogen. Adjusting the operating parameters during composting is an emerging in situ odor control technique that is cheap and highly efficient. The effects of in situ NH3 emission control were investigated in this study by simultaneously adjusting key operating parameters (such as C/N ratio, aeration rate, and moisture content) during the composting processes (C1–C9). Results showed that the average NH3 emission concentrations for different treatments were in the order of C1 > C4 > C2 > C5 > C3 > C6 > C7 > C8 > C9. The total content of NH3 emission (21.02 g/kg) in C9 (C/N ratio = 35, aeration rate = 15 L/min, and moisture content = 60%) was much lower than that (65.95 g/kg) in C1 (C/N ratio = 15, aeration rate = 5 L/min, and moisture content = 60%). The nitrogen loss ratio was 27.36% for C1, while 16.15% for C9. The microbial diversity and abundance in C9 and C1 were compared using high-throughput sequencing. The relationship between NH3 emission, operating parameters, and the related functional microbial communities was also investigated. Results revealed that Nitrosospira, Nitrosomonas, Nitrobacter, Pseudomonas, Methanosaeta, Rhodobacter, Paracoccus, and Sphingobacterium were negatively related to NH3 emission. According to the above results, the optimal values for different operating parameters for the in situ NH3 control during kitchen waste composting were, respectively, moisture content of 70%, C/N ratio of 35, and aeration rate of 15 L/min, with the order of effectiveness from high to low being aeration rate > C/N > moisture. This information could be used as a valuable reference for the in situ NH3 emission control during kitchen waste composting. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract The problems associated with heavy metal pollution require effective methods for their decontamination. Biosorption is an eco-friendly option to alleviate this problem. In this work, we propose the utility of Nitrosomonas modified Zirconium metal organic framework as a novel biosorbent for the remediation of toxic hexavalent chromium. Detailed analytical characterization of the synthesized biosorbent was performed using various techniques such as Powder X-ray Diffraction (PXRD), Fourier Transform Infrared (FTIR), X-ray Photoelectron Spectroscopy (XPS), Thermo Gravimetric analysis (TGA), Optical microscopy, Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM), surface area and porosity measurements. The developed biosorbent has a surface area of 921 m2 g−1. Important batch adsorption parameters such as pH variation, adsorbent dosage, kinetics, isotherms and temperature variation were studied. A multilayer Freundlich adsorption and pseudo second order kinetics drive the exothermic biosorption process. The electrostatic interactions between the biosorbent surface and metal ions aid towards understanding the adsorption mechanism. Laboratory scale column studies were conducted and the regeneration of the biosorbent was done using sodium hydroxide. The validity of the method was tested in a certified reference material BCR-032 (Moroccan rock phosphate) for the removal of total chromium. [ABSTRACT FROM AUTHOR]

Highlights • The rapid start-up of partial nitritation was achieved using short-term starvation. • The inhibition of starvation on NOB activity was higher than that on AerAOB activity. • Nitrite accumulation was observed in nitrifying system after short-term starvation. • The dominant species of AerAOB were Nitrosomonas and Nitrosomonadaceae_uncultured. Abstract Partial nitritation is a key step toward cost-effective shortcut biological nitrogen removal and anammox process. The current study presents a novel method for achieving partial nitritation at influent ammonium nitrogen concentration of 100 mgNL−1 using short-term starvation and low air flow rate. Mixed activated sludge was introduced into sequencing batch reactor (SBR) under aerobic/anaerobic condition. Variations in the reactor performance, nitrifying bacteria activities, and bacterial community structures were investigated. The results showed that partial nitritation was rapidly achieved, and an average nitrite accumulation rate (NAR) of 878 gNm−3d−1 was observed. The short-term starvation stress on nitrite oxidation bacteria (NOB) activity was relatively higher than that on aerobic ammonium oxidation bacteria (AerAOB) activity. The dominant species of general AerAOB were Nitrosomonas and Nitrosomonadaceae_uncultured , which had better self-adaption to short-term starvation. The moderate starvation could be utilized to achieve nitrite accumulation and nitritation. [ABSTRACT FROM AUTHOR]

Aims: Root exudates of rice (Oryza sativa L.) can inhibit nitrification in Nitrosomonas bioassays, and 1,9-decanediol was recently identified as an important new biological nitrification inhibitor (BNI) from rice. However, the release characteristics of 1,9-decanediol have not been studied. The present study was designed to identify the major factors influencing the release of 1,9-decanediol from rice roots.Methods: Rice plants were hydroponically grown in controlled environment chambers for 6 weeks, and root exudates were collected. Responses of exudate release to nitrogen form and concentration, pH, aeration, and bacterial inoculation were explored. The pH of root exudates, collected under different nitrogen-provision regimes, was determined, and 1,9-decanediol levels in exudates were monitored.Results: Ammonium (NH4+) and low pH in the root environment stimulated the release of 1,9-decanediol from rice roots. When only a part of the root system was exposed to NH4+, the secretion of 1,9-decanediol was triggered in the whole root system. Aeration of the root environment significantly enhanced 1,9-decanediol release. The presence of two major nitrifiers (Nitrosomonas europaea and Nitrosomonas stercoris) in the root medium stimulated release of 1,9-decanediol, whereas denitrifiers had no effect.Conclusions: Our results demonstrate that the release of 1,9-decanediol is enhanced by low to moderate concentrations of NH4+ (≤1.0 mM), low pH, and aeration of the rhizosphere. Our study provides the first evidence of significant 1,9-decanediol secretion induced by nitrifying bacteria. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Oxygen or ammonia limited condition was adverse to achieve nitrite accumulation. • Different AOB with similar oxygen sensitivity were enriched in the two reactors. • Nitrospira defluvii dominated both reactors but had different oxygen affinity. • Ammonia and nitrite levels were the key factors for selection of the nitrifiers. Abstract For understanding the potential of achieving nitritation under different oxygen and ammonia levels, two activated sludge reactors with high (R H) and low (R L) dissolved oxygen (DO) were parallelly operated. During over two months continuous operation, rare nitrite accumulation was observed in both reactors. K -strategists Nitrosomonas oligotropha and r -strategists Nitrosomonas europaea were enriched in the R H and R L , respectively, yet their response to DO variations was almost identical. Although K -strategists Nitrospira defluvii dominated both reactors, species cultured with low-DO exhibited higher oxygen affinity. Instead of DO, ammonia and nitrite availability should be the key factor for the selective enrichment of these nitrifiers. Taken together, the limiting ammonia for ammonia oxidizing bacteria and the better oxygen-uptake capacity of nitrite oxidizing bacteria was respectively responsible for the failure of nitrite accumulation in the R H and R L. This study supported that high DO coupled with excess ammonia would favor the achievement of mainstream nitritation. [ABSTRACT FROM AUTHOR]

Operating process at low dissolved oxygen (DO) concentrations is a good way to reduce the energy costs in wastewater treatment. Considering the limited DO concentrations (0.2~0.3 mg/L), it remains unclear whether nitrification will be achieved and which microbial groups are affected during the process. In the study, nitrification was realized in the nitrifying reactor at limited DO concentrations (0.2~0.3 mg/L), and the bacterial community both in the nitrifying sludge and the seeding sludge almost has the same phyla after over two months operation. However, autotrophs of Nitrosomonadales instead of heterotrophs of Burkholderiales and Rhodocy-clales finally became the dominant microbes in nitrifying sludge. Regarding nitrifiers, the respective abundance of nitrite oxidizing bacteria (NOB) of Nitrospira and ammonium oxidizing bacteria (AOB) of Nitrosomonas were 2.41% and 37.4% in nitrifying sludge. In spite of the low ratio of NOB to AOB, the reactor performed nitratation process rather than ni-tritation process. The study characterized the microbial community shift, evidenced that efficient nitrification can occur at limited DO concentrations (0.2~0.3 mg/L), and demonstrated the relationship between performance and microbial structure in the nitrification reactor. [ABSTRACT FROM AUTHOR]

Aquaculture ponds are simple and unique ecosystems, which are affected intensively by human activities. In this mini-review, we focus our attention on the distribution and community diversity of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) in pond water and sediments, as well as the possible ecological mechanisms involved. Moreover, we discuss the possibility of increasing the activity of ammonia-oxidizing organisms in order to improve the water quality in aquaculture ponds. Compared with eutrophic lakes, the significantly higher ammonia concentration in pond water does not lead to significantly higher AOB levels, and the abundance of AOA is too low to quantify accurately. Similar to eutrophic lakes, high abundances of AOA and AOB are present in the surface sediments at the same time, where the oxidation of ammonia is performed mainly by AOB. AOB and AOA exhibit significant seasonal variations in aquaculture ponds, which are affected by the temperature, pH, and dissolved oxygen. The dominant AOB species are Nitrosomonas and the Nitrosospira lineage in pond environments. Nitrososphaera or members of the Nitrososphaera-like cluster dominate the AOA species in surface sediments, whereas the Nitrosopumilus cluster dominates the deeper sediments. AOB and AOA can be enriched on artificial substrates suspended in the pond water, thereby potentially improving the water quality. [ABSTRACT FROM AUTHOR]

Abstract The application of biological nitrification inhibitors (BNIs) is considered an important new strategy to mitigate nitrogen losses from agricultural soils. 1,9-decanediol was recently identified as a new BNI in rice root exudates and was shown to inhibit nitrification in bioassays using Nitrosomonas. However, the effect of this compound on nitrification and ammonia oxidizers in soils remained unknown. In this study, three typical agriculture soils were collected to investigate the impact of 1,9-decanediol on nitrification and ammonia oxidizers in a 14-day microcosm incubation. High doses of 1,9-decanediol showed strong soil nitrification inhibition in all three agricultural soils, with the highest inhibition of 58.1% achieved in the acidic red soil, 37.0% in the alkaline fluvo-aquic soil, and 35.7% in the neutral paddy soil following 14 days of incubation. Moreover, the inhibition of 1,9-decanediol was superior to the widely used synthetic nitrification inhibitor, dicyandiamide (DCD) and two other BNIs, methyl 3-(4-hydroxyphenyl) propionate (MHPP) and α-linolenic acid (LN), in all three soils. The abundance of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) was significantly inhibited by 1,9-decanediol addition across the three soils. All AOB sequences fell within the Nitrosospira group, and the dominant AOA sequences belonged to the Nitrososphaera cluster in all three soils. Changes in the community composition of AOB were more pronounced than AOA after the application of 1,9-decanediol. The AOB community structure shifted from Nitrosospira cluster 2 and cluster 3a toward Nitrosospira clusters 8a and 8b. As for AOA, no significant impact on the proportion of the dominant Nitrososphaera cluster was observed in the fluvo-aquic soil and paddy soil while only the Nitrosopumilus cluster decreased in the red soil. 1,9-decanediol could also significantly reduce soil N 2 O emissions, especially in acidic red soil. Our results provide evidence that 1,9-decanediol is capable of suppressing nitrification in agricultural soils through impeding both AOA and AOB rather than affecting soil NH 4 + availability. 1,9-decanediol holds promise as an effective biological nitrification inhibitor for soil ammonia-oxidizing bacteria and archaea. Highlights • 1,9-decanediol can inhibit soil nitrification. • The inhibition of 1,9-decanediol is superior to that of DCD and two other BNIs. • 1,9-decanediol inhibits nitrification by impeding both AOA and AOB. • 1,9-decanediol can reduce N 2 O emissions, especially in acidic red soils. [ABSTRACT FROM AUTHOR]

Abstract Cathodic oxygen reduction catalyzed by autotrophic bacteria instead of a precious metal is a promising method to make use of microbial fuel cells (MFCs) in wastewater treatment with electricity production. However, the ecology of electrotrophic microbial consortia in wastewater systems that function as the catalyst for cathodic oxygen reduction is complicated and the electron transfer mechanisms are still unknown, which prevents further improvements of the biocathode performance. Enriched by the repeated transfer of a mature electrotrophic microbial consortia to new cathodes over 10 generations in 230 days, the start-up time was shortened from 21.4 to 7.6 days and the maximum current densities over the potential range of 0.5 to − 0.3 V increased by up to 112%, from 75 ± 5 A m−3 to 159 ± 3 A m−3, which was further confirmed in half-cell biocathode systems. The electrotrophic microbial consortia approached a relatively stable state after 8 generations. Acinetobacter , which is a member of Proteobacteria , was selectively enriched after 10 generations, which was closely related to the current production. Nitrospiraceae and Nitrosomonas may jointly perform a nitrogen cycling metabolic process and promote cathodic bioelectron transfer. Our findings confirmed that the electrotrophic microbial consortia on the cathode was able to be specifically evolved, leading to higher electroactivity, and also revealed which bacteria in fresh water are closely related to cathodic electron transfer. Highlights • Biocathodic bacterial communities evolved after repeated transfers of subcultures. • The start time was shortened from 21.4 to 7.6 days after 10 generations of transfer. • The current densities were improved by 112–124% after 10 generations of transfer. • Electrotrophic microbial consortia approached a stable state after 8 generations. • Acinetobacter, Nitrospiraceae and Nitrosomonas were selectively enriched. [ABSTRACT FROM AUTHOR]

Highlights • Partial nitrification granular sludge was successfully cultivated in a SBR. • The effluent NH 4 +-N/NO 2 −-N ratio was about 1:1 with NAR at 87.8%. • MLSS and SVI 30 of SBR were 14.6 g/L and 25.0 mL/g, respectively. • Nitrosomonas affiliated to the AOB was the predominant group. Abstract Partial nitrification granular sludge was successfully cultivated in a sequencing batch reactor as a pretreatment for anaerobic ammonium oxidation (Anammox) through shortening settling time. After 250-days operation, the effluent NH 4 +-N and NO 2 −-N concentrations were average at 277.5 and 280.5 mg/L with nitrite accumulation rate of 87.8%, making it as an ideal influent for Anammox. Simultaneous free ammonia (FA) and free nitrous acid (FNA) played major inhibitory roles on the activity of nitrite oxidizing bacteria (NOB). The MLSS and SVI 30 of partial nitrification reactor were 14.6 g/L and 25.0 mL/g, respectively. Polysaccharide (PS) and protein (PN) amounts in extracellular polymeric substances (EPS) from granular sludge were about 1.3 and 2.8 times higher than from seed sludge. High-throughput pyrosequencing results indicated that Nitrosomonas affiliated to the ammonia oxidizing bacteria (AOB) was the predominant group with a proportion of 24.1% in the partial nitrification system. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of SO 4 2− on anammox was studied in two sequencing batch reactors. • The increased SO 4 2− concentrations improved utilization rates of NH 4 + and NO 2 –. • The highest SO 4 2− utilization rates were obtained in the absence of NO 2 –. • The predominant role in the N-S metabolism was related to Nitrosomonas and Thauera. • N and SO 4 2− rich wastewater can be treated in a sustainable way in one-stage system. The Anammox and Sulfate Reduction Ammonium Oxidation processes were compared in two granular sequencing batch reactors operated for 160 days under anammox conditions. It was hypothesized that increasing the concentration of SO 4 2− may positively influence the rate of N removal under anaerobic conditions and it was tested whether SO 4 2− reduction and anammox occur independently or are related to each other. The cooperation of N-S cycles by increasing the concentration of influent SO 4 2− to 952 mg S/L in the second reactor, a higher ammonium utilization rate and sulfate utilization rate was achieved compared to the first reactor, i.e., 2.1-fold and 15-fold, respectively. Nitrosomonas played the dominant role in the N metabolism, while Thauera – in the S metabolism. This study highlights the benefits of linking the N-S cycles as an effective approach for the treatment of NH 4 + and SO 4 2− – rich wastewater, including lower substrate removal cost and reduced energy consumption. [ABSTRACT FROM AUTHOR]

The stress response of ammonia-oxidizing bacteria (AOB) to oxygen deprivation limits AOB growth and leads to different nitrification pathways that cause the release of greenhouse gases. Measuring the stress response of AOB has proven to be a challenge due to the low growth rates of stressed AOB, making the sample volumes required to monitor the internal stress response of AOB prohibitive to repeated analysis. In a proof-of-concept study, confocal Raman microscopy with excitation resonant to the heme c moiety of cytochrome c was used to compare the cytochrome c content and activity of stressed and unstressed Nitrosomonas europaea (Nm 50), Nitrosomonas eutropha (Nm 57), Nitrosospira briensis (Nsp 10), and Nitrosospira sp. (Nsp 02) in vivo. Each analysis required no more than 1000 individual cells per sampling; thus, the monitoring of cultures with low cell concentrations was possible. The identified spectral marker delivered reproducible results within the signal-to-noise ratio of the underlying Raman spectra. Cytochrome c content was found to be elevated in oxygen-deprived and previously oxygen-deprived samples. In addition, cells with predominantly ferrous cytochrome c content were found in deprived Nitrosomonas eutropha and Nitrosospira samples, which may be indicative of ongoing electron storage at the time of measurement.

In this study, a laboratory-scale partial nitrification reactor (PN reactor) was used to treat high-ammonia-nitrogen wastewater, by changing the influent NH 4 + -N conversion rate as the main operating strategy, to investigate the upper limit of its NH 4 + -N conversion rate (ACR) and explore its feasibility as an anammox pre-process. During the experiment, PN reactor was successfully activated in only 10 days. The PN reactor reached the highest ACR value of approximately 10.24 kg N/(m 3 · day) when the influent ACR was 16.57 kg N/(m 3 · day), and the ammonia conversion efficiency (ACE) was 61.78% at this time. The ratio of [NO 2 - was approximately 1.37 which was close to the theoretical ratio of 1.32. And feasibility exploration experiment proved that it was feasible to use this PN reactor as a pre-process of anammox. The PCR-DGGE results showed that the dominant phylum and genus in the reactor during the ACR experiment were Proteobacteria and Nitrosomonas, respectively. With the increase in the ACR, the relative concentration of Nitrosomonas sp. G1 increased from 15 to 40%. This indicates that its abundance is directly correlated with the increase in the ACR. High-throughput sequencing showed that increasing the ACR of the PN reactor greatly reduced the diversity and abundance of the system microbial community structure and changed the dominant phylum and genus; however, the stability of the system was not disrupted. High-throughput sequencing experiments showed that the abundance value of nitrosation enzymes accounted for 91.62%, which was positively correlated with the expression of nitrification genes in the genus Nitrosomonas.Eff /[NH 4 + -N] Eff was approximately 1.37 which was close to the theoretical ratio of 1.32. And feasibility exploration experiment proved that it was feasible to use this PN reactor as a pre-process of anammox. The PCR-DGGE results showed that the dominant phylum and genus in the reactor during the ACR experiment were Proteobacteria and Nitrosomonas, respectively. With the increase in the ACR, the relative concentration of Nitrosomonas sp. G1 increased from 15 to 40%. This indicates that its abundance is directly correlated with the increase in the ACR. High-throughput sequencing showed that increasing the ACR of the PN reactor greatly reduced the diversity and abundance of the system microbial community structure and changed the dominant phylum and genus; however, the stability of the system was not disrupted. High-throughput sequencing experiments showed that the abundance value of nitrosation enzymes accounted for 91.62%, which was positively correlated with the expression of nitrification genes in the genus Nitrosomonas., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Graphical abstract Highlights • Wastewater types showed obvious effects on bacterial communities and functions. • Among 12 potential pathogens, Mycobacterium showed highest relative abundance. • Efflux pumps were the most common resistance mechanisms for 69 predicted ARGs. • ARGs/MRGs in industrial and mixed wastewater differed from municipal wastewater. • ARGs were linked to MRGs, functional genera and potential pathogens in WWTPs. Abstract This study aimed to investigate the bacterial communities and antibiotic resistance genes (ARGs) in 16 wastewater treatment plants (WWTPs) treating municipal, industrial and mixed wastewater. Wastewater types showed obvious effects on bacterial communities and functions. Nitrosomonas , Nitrospira , Hyphomicrobium and Accumulibacter were the main functional genera. Mycobacterium was the dominant potential pathogens. A total of 69 ARGs were obtained, and the dominant ARGs subtypes were similar in different WWTPs. Efflux pumps were the most common resistance mechanisms. Copper and zinc resistance genes were the main metal resistance genes (MRGs). Wastewater types affected the distributions of ARGs and MRGs, and they were more similar in industrial and mixed wastewater. The co-occurrence of ARGs existed within or across ARG types, and they were also positively linked to MRGs, some functional and pathogenic genera or environmental factors. This study furthers the understanding of interactions between bacterial communities, ARGs and MRGs in different WWTPs. [ABSTRACT FROM AUTHOR]

Here, we employed DNA-based stable isotope probing (SIP) and molecular biology methods to investigate active ammonia oxidizer communities in suboxic sediments (0 to -2 cm) at the micromolar oxygen level and layers (-2 to -5 cm) at nanomolar oxygen concentrations from meso-eutrophic and light-eutrophic locations in Taihu Lake. The results revealed that ammonia-oxidizing archaea (AOA) were less active in the anoxic layer of meso-eutrophic sites, while ammonia-oxidizing bacteria (AOB) were less active in suboxic sediments of light-eutrophic sites after 8 weeks of incubation. The active AOA in the meso- and light-eutrophic sediments belonged to the Nitrosopumilus, Nitrosotalea, and Nitrososphaera clusters and the Nitrosopumilus and Nitrososphaera clusters, respectively, with Nitrosopumilus cluster as the predominant AOA, which took up a higher ratio in the light-eutrophic and suboxic layers than their counterparts. The advantageous active AOB were numerically predominated by the Nitrosomonas cluster in the suboxic layers, and the Nitrosospira cluster in the anoxic layers, respectively, both of which were distributed in diverse frequencies in different eutrophication statuses. The role and community composition diversities of active ammonia oxidizers in freshwater sediments were attributed to the different eutrophication (including nitrogen and organic carbon content) and oxygen statuses. [ABSTRACT FROM AUTHOR]

An efficient and stable combined denitrification-partial nitrification-Anammox process with a dual recycling system was used to remove nitrogen from mature landfill leachate. After 155 d of operation, the NO 3 − as the PN-Anammox byproduct was almost treated with biodegradable organic carbon in raw wastewater in a pre-denitrification reactor by external recycling system. When raw landfill leachate with NH 4 + -N concentration of 1900 mg/L was treated, an integrated reactor with airlift recycling was combined with the PN and Anammox reactions to efficiently remove NH 4 + from the inflow. The total nitrogen concentration of effluent stabilized at 20 mg/L and total nitrogen removal efficiency was 99%. The maximum NO 2 − production rate in the aerobic zone was 2.2 kg/(m 3 ·d) and the maximum nitrogen removal rate in the anaerobic zone was 21.4 kg/(m 3 ·d). The most common phyla among the nitrification and the Anammox functional bacteria were Nitrosomonas , Candidatus Kuenenia, and Candidatus Brocadia after landfill leachate treatment. [ABSTRACT FROM AUTHOR]

Nitrification at the site of a contaminant ammonium plume from a former coal carbonisation plant can be modelled with three competing bacterial populations of Nitrosomonas, Nitrobacter, and Brocadia anammoxidans. Oscillations of chemical species at the site can be explained by a reduced model of ammonium competition between Nitrosomonas and B. anammoxidans which effectively acts as an activator-inhibitor system. Stable oscillations occur in conditions of low nutrient (ammonium) supply and this causes a spatial travelling wave in a borehole profile when diffusion is introduced. [ABSTRACT FROM AUTHOR]

Simultaneous removal of organics, nitrogen and phosphorus was achieved in a bench-scale oxygen-limited membrane bioreactor (OLMBR). Due to the limited dissolved oxygen (~ 0.2 mg/L equilibrium concentration) and the increased sludge concentration associated with the hollow fiber membrane, the OLMBR was endowed with an excellent performance on the removal of multi-pollutants. The optimized removal efficiencies of COD, nitrogen (N), and total phosphorus (TP) were approximately 95.5%, 90.0% and 82.6%, respectively (COD/N/P = 500:10:1, influent loading = 5.0 kg COD·m-3·d-1, 35°C). Mass balance and bacterial community analysis indicated that the removal of organic carbon was mainly achieved by the methane production process (67.6%). Short-cut nitrification-denitrification (SCND) was observed as the primary denitrification process in the OLMBR, in which the concentrated organic compounds served as the electron donors for denitrification. Nitrosomonas was observed to be the predominant ammonium-oxidizing bacteria, while nitrite-oxidizing bacteria were almost absent in the microbial community as revealed by the high-throughput sequencing technique. In addition, Euryarchaeota and Candidatus, which were well associated with the process of denitrifying anaerobic methane oxidation, were also detected. Sludge absorption was the main route for TP removal in the OLMBR, and the production of PH3 gas also accounted for 19.4% of TP removal. This study suggested that the interception effect of hollow fiber membrane provided higher sludge concentration, therefore offering more bacteria for pollutant removal. The OLMBR can be used for simultaneous removal of highly concentrated organics and nutrients in livestock and poultry breeding wastewater. [ABSTRACT FROM AUTHOR]

The effects of influent shift from synthetic wastewater to anaerobically pretreated actual sewage coupling with lowering temperature on microbial community of a two-stage partial nitritation (PN)-anammox process were evaluated through high-throughput sequencing. Venn diagrams and Hill numbers showed the significantly increased bacterial diversity both in the PN and anammox reactor. However, taxonomic analysis indicated that outstanding enrichment of heterotrophic bacteria and reduction of autotrophic species mainly occurred in the PN reactor, while nearly all of the dominant bacteria in the anammox reactor only slightly decreased in abundance. Moreover, immigrant bacteria from the PN reactor to the following anammox reactor had no negative effect on the anammox function. These results implied the positive role of the first-stage PN in maintaining the stability of the following anammox community. Nitrosomonas europaea (17.9–52.9%) and one cluster (19.2–27.7%) within Candidatus Brocadia remained as the dominant functional species in the PN and anammox reactor, respectively. [ABSTRACT FROM AUTHOR]

An integrated approach to document high ammonium oxidation rate in Guanjinggang constructed wetland (GJG-CW) was performed and the results showed that the substantial ammonium oxidation rate could be obtained by enhancing Ammonia Oxidizing Bacteria (AOB) activity rather than Ammonia Oxidizing Archaea (AOA) activity. In the plant-bed/ditch system, ditch center and plant-bed fringe were two active zones for NH 4 + -N removal with ammonium oxidation rate peaking at 2.98 ± 0.04 and 2.15 ± 0.02 mg N kg − 1 d − 1 , respectively. The enhanced AOB activity were achieved by increasing water level fluctuations, extending hydraulic retention time (HRT) and stimulating substrate availability, which subsequently enhanced NH 4 + -N removal by 34.06% in GJG-CW. However, the high AOB activity was not correlated with high AOB abundance, but was instead mostly determined by specific AOB taxa, particularly Nitrosomonas, which dominated in the active AOB. The increased cell-specific AOA activity and high AOA diversity were also achieved using those engineering measures. Although the AOA activity decreased overall with extended HRT and increased NH 4 + -N contents in GJG-CW, AOA still played a major role on ammonium oxidation in plant-bed soil. The study illustrated that artificially enhancing AOB activity and certain species in anthropogenically polluted water ecosystems would be an effective strategy to improve NH 4 + -N removal. [ABSTRACT FROM AUTHOR]

A full-scale wastewater treatment plant (WWTP) with three separate treatment processes was selected to investigate the effects of seasonality and treatment process on the community structures of ammonia-oxidizing archaea (AOA) and bacteria (AOB). And then DNA-based stable isotope probing (DNA-SIP) was applied to explore the active ammonia oxidizers. The results of high-throughput sequencing indicated that treatment processes varied AOB communities rather than AOA communities. AOA slightly outnumbered AOB in most of the samples, whose abundance was significantly correlated with temperature. DNA-SIP results showed that the majority of AOB amoA gene was labeled by 13 C-substrate, while just a small amount of AOA amoA gene was labeled. As revealed by high-throughput sequencing of heavy DNA, Nitrosomonadaceae -like AOB, Nitrosomonas sp. NP1, Nitrosomonas oligotropha and Nitrosomonas marina were the active AOB, and Nitrososphaera viennensis dominated the active AOA. The results indicated that AOB, not AOA, dominated active ammonia oxidation in the test WWTP. [ABSTRACT FROM AUTHOR]

The completely autotrophic nitrogen removal over nitrite (CANON) process is an important component of energy self-sufficient sewage treatment plants, and the use of aerobic granular sludge is a profitable choice for the CANON process. In this study, the performance and microbial characteristics of CANON granular sludge were investigated for treating synthetic and mainstream domestic sewage. The average nitrogen removal rate (NRR) was 3.22 kg N m −3  d −1 during the high-rate operating period with high MLSS (4.09 g L −1 ) and DO (∼1.0 mg L −1 ) for treating synthetic sewage. When the influent was mainstream sewage, the average NRR was 1.11 kg N m −3  d −1 . The effluent nitrate concentration was very low, and nitrate build-up was not found. High-throughput pyrosequencing results indicated that, Nitrosomonas and Candidatus Brocadia were the dominant genus in ammonia oxidizing bacteria (AOB) and anaerobic AOB (AAOB), respectively. The proportions of AOB and AAOB decreased during mainstream sewage treatment, but the reactor maintained good performance. The results confirmed the feasibility of using CANON granular sludge for treating mainstream sewage. [ABSTRACT FROM AUTHOR]