Nitrification Activity Research Articles

Dietary nitrate supplementation to enhance exercise capacity in patients with COPD: Evidence from a meta-analysis of randomized controlled trials and a network pharmacological analysis

ObjectiveThe potential effects of nitrate in patients with chronic obstructive pulmonary disease (COPD) have attracted increased research interest. However, previous clinical trials have reported inconsistent results, and consecutive meta-analyses have failed to reach a consensus. Since some randomized controlled trials have recently been conducted that can provide more evidence, we performed an updated meta-analysis. MethodsA comprehensive literature search was conducted using PubMed, the Cochrane Library, Embase, and Web of Science databases to identify trials that assessed the efficacy and safety of nitrate in patients with COPD. The Revman 5.3 software was used for data analysis. Mean difference (MD) or standardized mean difference (SMD) with 95 % confidence interval (CI) was used as the effect measure, and forest plots were used to display individual and pooled results. Network pharmacology analysis was conducted to investigate the potential mechanisms of nitrate action in COPD. ResultsEleven studies involving 287 patients were included in this meta-analysis. The results indicated that dietary nitrate supplementation increased plasma nitrate and nitrite concentrations and fractional exhaled nitric oxide in patients with COPD. Nitrate improved exercise capacity [SMD = 0.38, 95 % CI = 0.04–0.72] and endothelial function [MD = 9.41, 95 % CI = 5.30–13.52], and relieved dyspnea in patients with COPD. Network pharmacology identified AKT1, IL1B, MAPK3, and CASP3 as key treatment targets. ConclusionDietary nitrate supplementation could be used as a potential treatment for patients with COPD, especially to increase their exercise capacity. The underlying mechanisms may be related to AKT1, IL1B, MAPK3, and CASP3.

Visualizing small-scale subsurface NH3 and pH dynamics surrounding nitrogen fertilizer granules and impacts on nitrification activity

In agricultural soils, nitrogen (N) fertilizer is typically applied as ammonium salts or urea, and undergoes microbially mediated oxidation. However, insights regarding substrate concentrations nitrifiers are exposed to in the zones immediately surrounding N fertilizer granules remain unexamined, as well as how this affects the activity or inhibition of nitrifier groups adapted to different ranges of ammonia (NH3) concentrations. To examine millimeter scale changes in soil chemistry after sub-surface fertilizer granule application with high spatiotemporal resolution, we applied a newly developed NH3 and pH planar optical sensor (optode) system. With this system, we visualized in situ subsurface NH3 production, diffusion, and associated pH shifts in an agricultural soil following the application (from 5 min up to 65.5 h) of ammonium chloride (NH4Cl) or urea granules in a laboratory study. Ammonia from both NH4Cl and urea granules diffused up to 1.5 and 2 cm and reached maximum concentrations of >49 and >130 ppmv, respectively. Spatially informed destructive subsampling (0.5–2 cm from granules) revealed that nitrate accumulation was greatest closest (0.5–1 cm) to the ammonium chloride granules, while nitrite was not detected. In contrast, urea application resulted in both nitrite and nitrate accumulation, with the highest concentrations detected furthest (1.5–2 cm) from urea granules. Urea hydrolysis also caused a significant localized pH increase, while ammonium chloride caused a circular elevated pH zone migrating outwards leaving a decreased pH at the center. Transcription of the ammonia-oxidizing bacterial amoA gene was highest in areas furthest (1.5–2 cm) from the urea granules, while there were no significant differences in amoA transcription with increasing distance from the NH4Cl granules. Ammonia-oxidizing archaea and comammox amoA transcripts were not detected. This study is the first to directly visualize small-scale subsurface changes in NH3 concentration and pH after fertilizer granule application and relate these to nitrification activity.

Straw incorporation into microplastic-contaminated soil can reduce greenhouse gas emissions by enhancing soil enzyme activities and microbial community structure

Microplastic (MP) contamination poses a substantial threat to agroecosystems, disrupting soil properties, nutrient cycles, and microbial communities and ultimately affecting plant growth and ecosystem resilience. The effects of straw addition on the storage of soil organic carbon (SOC) and greenhouse gas emissions have been extensively explored, but these effects have not been examined in the context of MP contamination. To assess the impacts of legume straw and polyethylene microplastics on SOC fractions and carbon dioxide (CO2) and nitrous oxide (N2O) emissions, 7-month soil incubation experiments were performed. The results revealed that the inclusion of legume straw in soil considerably increased microbial SOC compared to the control. However, straw addition to MP-contaminated soil reduced microbial SOC compared to that in soil containing only straw. In contrast, the addition of straw to MP-contaminated soil elevated (+44%) the SOC mineral relative to the sole application of straw. Intriguingly, straw incorporation into MP-contaminated soil reduced microbial biomass carbon and nitrogen relative to soil containing only straw. Straw addition to MP-contaminated soil enhanced the nitrification activity and reduced the relative expression of AOBamoABC gene compared to sole straw-incorporated soil and the control. Greenhouse gas emissions were also modulated; for instance, straw incorporation into MP-contaminated soil reduced CO2 and N2O emissions by −11% and −46%, compared to straw incorporation alone. The urease and phosphatase activities were decreased (−58% and −12%) in the MP-polluted soil with straw incorporation compared with those in the soil in which only straw was applied. However, invertase and catalase activities were upregulated in the straw-incorporated soil contaminated with MPs. Straw addition in the MP-polluted soil considerably enhanced (+2%) the microbial community structure (indicated by PLFA) compared to the sole straw application. These results provide a comprehensive perspective on the role of legume straw incorporation in addressing MP pollution, showcasing its potential for sustainable agricultural practices in the face of evolving environmental challenges.

Short-Term Nitrous Oxide Emissions from Cattle Slurry for Silage Maize: Effects of Placement and the Nitrification Inhibitor 3,4-Dimethylpyrazole Phosphate (DMPP)

Cattle slurry is an important nitrogen source for maize on dairy farms. Slurry injection is an effective measure to reduce ammonia emissions after field application, but with higher risk of nitrous oxide emission than surface application. This study compared soil mineral nitrogen dynamics and nitrous oxide emissions with two ways of application. First, traditional injection at 25 cm spacing between rows followed by ploughing (called “non-placed slurry”), and second, injection using a new so-called goosefoot slurry injector that placed the slurry in ploughed soil as a 30 cm broad band at 10 cm depth below maize crop rows with 75 cm spacing (named “placed slurry”). Furthermore, the effect of treating slurry with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) in Vizura® was tested with both application methods. The field experiment was conducted on a sandy loam soil in a temperate climate. Both nitrous oxide emissions, and the dynamics of soil mineral nitrogen, were monitored for eight weeks after slurry application and seeding of maize using static chambers. The level of nitrous oxide emissions was higher with non-placed compared to placed slurry (p < 0.01), mainly due to higher emissions during the first four weeks. This might be due to higher rates of nitrification and in turn stimulation of denitrification. In both placed and non-placed slurry treatments, Vizura® caused higher soil ammonium concentrations and lower nitrate concentrations (p < 0.001), particularly from 3 to 8 weeks after slurry application. The final level of soil nitrate was similar with and without the nitrification inhibitor, but higher with placed compared to non-placed slurry. Adding Vizura® to non-placed slurry reduced nitrous oxide emissions by 70% when compared to untreated slurry. Surprisingly, there was a non-significant trend towards higher cumulative emissions from placed slurry with the nitrification inhibitor compared to untreated slurry, which was due to higher emissions in the last part of the monitoring period (5–7 weeks after slurry application). Possibly, degradation of the nitrification inhibitor and nitrification activity inside the slurry band as the soil dried promoted nitrous oxide emissions by this time. In summary, placement of untreated slurry in a broad band under maize seeds reduced nitrous oxide emissions compared to non-placed slurry with more soil contact. A comparable reduction was achieved by adding a nitrification inhibitor to non-placed slurry. The pattern of nitrous oxide emissions from placed slurry treated with the inhibitor was complex and requires more investigation. The emission of nitrous oxide was highest when nitrate accumulated in soil around decomposing cattle slurry, and mitigation strategies should aim to prevent this. This study demonstrated a potential for mitigation of nitrous oxide emission by placement of cattle slurry, which may be an alternative to the use of a nitrification inhibitor.

Hydrological and Biogeochemical Controls of the Seasonality of Particulate and Dissolved Nitrogen Exports During Rainfall Events From a Forested Watershed in Monsoon Asia, Japan

AbstractFew studies have investigated the effects of hydrological conditions such as rainfall magnitude and soil nitrogen dynamics on nitrogen export from forests during rainfall events. In this study, the seasonal export of particulate and dissolved nitrogen during 24 rainfall events (range: 3.0–417 mm) in a temperate monsoon forest watershed in Japan was measured along with the seasonality of the soil nitrate () pool size and the nitrification rate. The increase in nitrogen export with increasing streamflow was larger for particulate nitrogen than for and dissolved organic nitrogen, but was always the most abundant nitrogen component exported, even during extreme rainfall. For all rainfall events in summer, measured exports were higher than the averaged exports, regardless of rainfall magnitude or preceding rainfall. Nitrification activity in the soil was high in summer because of the high temperature and wet conditions of the soil. Nitrification also occurred in the upper slope in summer, whereas during other seasons it is hindered by dry conditions. These results indicate that nitrogen dynamics in the soil also affect export during rainfall. Comparisons with previous studies suggested that the effects of soil nitrogen dynamics on concentrations in stream water may be stronger during rainfall than during base flow conditions. They also showed that regions with wet summers due to rainfall are more sensitive to export, compared with other regions, and that increased summer rainfall can have a particularly large impact on nitrogen export from forest watersheds.

Nitrification activity in the presence of 2-chlorophenol using whole nitrifying cells and cell-free extracts: batch and SBR assays.

The online version contains supplementary material available at 10.1007/s13205-023-03764-z.

Fertilization of Annual Grasses on Gray Forest Soils of the Vladimir Opole

In a long-term stationary experiment, the effect of fertilizers on the yield of annual grasses (vetch and pea mixtures) and the nitrifying activity of gray forest soils were studied. For 8 years, both without the use of fertilizers and with them, the yield of herbs changed by 1.72–1.88 times. It was found that the use of nitrogen of mineral fertilizers provided 88.3% of the total variation in their yield, the aftereffect of manure – 8.1, the aftereffect of РК fertilizers – 1.8%. For 7 out of 8 years, a high degree of correlation between the yield of grasses and the reserves of N-NO3 in the 0–40 cm layer of soil in the phase of grass germination was revealed. At the same time, the minimum reserves of N-NO3 were formed at a hydrothermal coefficient for the growing season equal to 1.21. The use of fertilizers, increased moisture content and temperatures during the growing season of grasses led to an increase in the nitrification activity of gray forest soil. It is proposed to evaluate the participation of mobile forms of nitrogen in plant nutrition in relation to the content of N-NO3 in the soil to the content of N-NH4 in the water extract (1 : 1). The values of this parameter in the phases of germination and harvesting of grasses confirmed the determining role of N-NO3 reserves in the nutrition of annual grasses. The difference coefficients of the use of nitrogen Naa in doses N60 and N75, which ranged from 40 to 49%, were calculated. An algorithm for calculating the size of the accumulation of N-NO3 during the growing season of grasses is proposed. In nitrogen-fertilized variants, a good coincidence of the utilization coefficients of accumulating N-NO3 reserves with the difference ones has been established.

The impact of fertilization on ammonia-oxidizing bacteria and comammox Nitrospira communities and the subsequent effect on N2O emission and maize yield in a semi-arid region.

The control of nitrous oxide (N2O) emissions through nitrification and the optimization of maize yield are important in agricultural systems. However, within the semi-arid region, the impact of fertilization on the function of nitrification communities and its connection with N2O emissions in the rhizosphere soil is still unclear. Our study investigates the influence of fertilization treatments on the communities of ammonia-oxidizing bacteria (AOB) and the complete ammonia oxidizers of the Nitrospira known as comammox (CAOB) in a maize agroecosystem. Nitrous oxide production, potential nitrification activity (PNA), maize yield, and nitrogen use efficiency (NUE) were determined for the same samples. The fertilizer treatments included a control group without fertilization (NA), inorganic fertilizer (CF), organic fertilizer (SM), combined inorganic and organic fertilizer (SC), and maize straw (MS). The SC treatment indicated a lower cumulative N2O emission than the CF treatment in the 2020 and 2021 cropping seasons. The AOB community under the CF, MS, and SM treatments was predominantly composed of Nitrosospira cluster 3b, while the SC treatment was associated with the comammox Nitrospira clade A.1 lineage, related to key species such as Ca. Nitrospira inopinata and Ca. Nitrospira nitrificans. Network analysis demonstrated a positive potential for competitive interaction between hub taxonomy and distinct keystone taxa among AOB and comammox Nitrospira nitrifiers. The structural equation model further revealed a significant positive association between AOB nitrifiers and N2O emission, PNA, soil pH, SOC, -N, and DON under organic fertilization. The keystone taxa in the comammox Nitrospira nitrifier and network Module II exhibited a positive correlation with maize productivity and NUE, likely due to their functional activities stimulated by the SC treatment. It is noteworthy that the AOB community played a more significant role in driving nitrification compared to the composition of comammox Nitrospira. Collectively, combined inorganic and organic fertilizer (SC) treatment exhibits high potential for reducing N2O emissions, enhancing maize productivity, increasing NUE, and increasing the sustainability of the nitrogen dynamics of maize agroecosystems in the semi-arid Loess Plateau.

Potential Secretory Transporters and Biosynthetic Precursors of Biological Nitrification Inhibitor 1,9-Decanediol in Rice as Revealed by Transcriptome and Metabolome Analyses

Biological nitrification inhibitors (BNIs) are released from plant roots and inhibit the nitrification activity of microorganisms in soils, reducing NO3‒ leaching and N2O emissions, and increasing nitrogen- use efficiency (NUE). Several recent studies have focused on the identification of new BNIs, yet little is known about the genetic loci that govern their biosynthesis and secretion. We applied a combined transcriptomic and metabolomic analysis to investigate possible biosynthetic pathways and transporters involved in the biosynthesis and release of BNI 1,9-decanediol (1,9-D), which was previously identified in rice root exudates. Our results linked four fatty acids, icosapentaenoic acid, linoleate, norlinolenic acid, and polyhydroxy-α,ω-divarboxylic acid, with 1,9-D biosynthesis and three transporter families, namely the ATP-binding cassette protein family, the multidrug and toxic compound extrusion family, and the major facilitator superfamily, with 1,9-D release from roots into the soil medium. Our finding provided candidates for further work on the genes implicated in the biosynthesis and secretion of 1,9-D and pinpoint genetic loci for crop breeding to improve NUE by enhancing 1,9-D secretion, with the potential to reduce NO3‒ leaching and N2O emissions from agricultural soils.

Factors regulating interaction among inorganic nitrogen and phosphorus species, plant uptake, and relevant cycling genes in a weakly alkaline soil treated with biochar and inorganic fertilizer

To highlight how biochar affects the interaction between inorganic nitrogen species (ammonium nitrogen, nitrate nitrogen, and nitrite nitrogen: NH4+-N, NO3¯-N, and NO2¯-N) and phosphorus species (calcium phosphate, iron phosphate, and aluminum phosphate: CaP, FeP and AlP) in soil and plant uptake of these nutrients, walnut shell (WS)- and corn cob (CC)-derived biochars (0.5 %, 1 %, 2 %, and 4 %, w/w) were added to a weakly alkaline soil, and then Chinese cabbages were planted. The results showed that the changes in soil inorganic nitrogen were related to biochar feedstock, pyrolysis temperature, and application rate. For soil under the active nitrification condition (dominant NO3¯-N), a significant decrease in the NH4+-N/NO3¯-N ratio after biochar addition indicates enhanced nitrification (excluding WS-derived biochars at 2 % and 4 %), which can be explained by the most positive response of ammonia-oxidizing archaeal amoA to biochar addition. The CC-derived biochar more effectively enhanced soil nitrification than WS-derived biochar did. The addition of 4 % of biochars significantly increased soil inorganic phosphorus, and the addition of CC-derived biochars more effectively increased Ca2P than WS-derived biochars. Biochars significantly decreased plant uptake of phosphorus, while generally had little influence on plant uptake of nitrogen. Interestingly, NO2¯-N in soil significantly positively correlated with total phosphorus in both soil and plant, and significantly negatively correlated with phoC, indicating that a certain degree of NO2¯-N accumulation in soil slightly facilitated plant uptake of phosphorus but inhibited phoC-harboring bacteria. The NO3¯-N in soil significantly positively correlated with Ca2P and Ca8P, while the NH4+-N/NO3¯-N ratio significantly negatively correlated with Ca10P and FeP, indicating that the enhanced nitrification seemed to facilitate the change in phosphorus to readly available ones. This study will help determine how to scientifically and rationally use biochar to regulate inorganic nitrogen and phosphorus species in soil and plant uptake of these nutrients.

Organic and inorganic nitrogen amendments reduce biodegradation of biodegradable plastic mulch films

Abstract. Biodegradable mulch films (BDMs) are a sustainable and promising alternative to non-biodegradable polyethylene mulches used in crop production systems. Nitrogen amendments in the form of fertilizers are used by growers to enhance soil and plant-available nutrients; however, there is limited research on how these additions impact the biodegradation of BDMs tilled into soils. A 4-month laboratory incubation study using soil microcosms was used to investigate the effects of inorganic (ammonium nitrate) and organic (urea and amino acids) nitrogen application on biodegradation of BDMs. We investigated the response of soil bacterial, fungal, and ammonia-oxidizing microbial abundance along with soil nitrogen pools and enzyme activities. Microcosms were comprised of soils from two diverse climates (Knoxville, TN, USA, and Mount Vernon, WA, USA) and BioAgri, a biodegradable mulch film made of Mater-Bi®, a bioplastic raw material containing starch and poly(butylene adipate-co-terephthalate) (PBAT). Both organic and inorganic nitrogen amendments inhibited mulch biodegradation, soil bacterial abundances, and enzyme activities. The greatest inhibition of mulch biodegradation in TN soils was observed with urea amendment where biodegradation was reduced by about 6 % compared to the no-nitrogen control. In WA soils, all nitrogen amendments suppressed biodegradation by about 1 % compared to the no-nitrogen control. Ammonia monooxygenase amoA gene abundances were increased in TN soils in all treatments but reduced for all treatments in WA soils. However, a significantly higher nitrate concentration and a lower ammonium concentration were seen for all nitrogen treatments compared to no-nitrogen controls in both TN and WA. This study suggests that the addition of nitrogen, particularly inorganic amendments, could slow down mulch biodegradation but that mulch biodegradation does not negatively affect soil nitrification activity.

Comammox plays a functionally important role in the nitrification of rice paddy soil with different nitrogen fertilization levels

Chemoautotrophic ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), and the recently discovered complete ammonia oxidizers (comammox) catalyze ammonia oxidation; however, quantifying their individual gross ammonia oxidation activities in complex soil ecosystems remains elusive. In this study, we investigated the nitrifying population and community dynamics in response to fertilization in paddy soil under long-term treatment with different urea concentrations (0, 100, 200, and 300 kg N ha−1; designated N0, N100, N200, and N300, respectively). The community structure of nitrifiers, including comammox, was changed by long-term N fertilizers input, which also enhanced AOB abundance and comammox clade A/B abundance ratio, whereas it did not affect AOA abundance. Nevertheless, the microbial population sizes and community compositions remained largely similar following short-term fertilization throughout one rice-growing season. Furthermore, by employing a 15NO3− pool dilution technique in combination with chlorate and 1-octyne inhibition, we conducted a soil microcosm incubation without substrate supplementation to distinguish the relative contribution of comammox to gross ammonia oxidation from those of AOA and AOB. Comammox exhibited higher nitrification activity in soils treated with more N fertilizers, with the contribution increasing from 34 % (N0) to 75 % (N300), although its abundance was not dominant. This could be attributed to the repeated N-based fertilization, which reduced the soil pH, thereby decreasing the soil-free ammonia concentration. In contrast, the contribution of AOA declined from 57 % (N0) to 19 % (N300), while that of AOB only accounted for a minor fraction (<25 %) despite being in high abundance. Altogether, our findings provide evidence that the activity of nitrifying guilds is more valuable than their abundance and provide insights into the potential functional significance of comammox in the nitrification process in rice paddy systems.

Toward Integrating EBPR and the Short-Cut Nitrogen Removal Process in a One-Stage System for Treating High-Strength Wastewater.

Enhanced biological phosphorus removal (EBPR) is an economical and sustainable process for phosphorus removal from wastewater. Despite the widespread application of EBPR for low-strength domestic wastewater treatment, limited investigations have been conducted to apply EBPR to the high-strength wastewaters, particularly, the integration of EBPR and the short-cut nitrogen removal process in the one-stage system remains challenging. Herein, we reported a novel proof-of-concept demonstration of integrating EBPR and nitritation (oxidation of ammonium to nitrite) in a one-stage sequencing batch reactor to achieve simultaneous high-strength phosphorus and short-cut nitrogen removal. Excellent EBPR performance of effluent 0.8 ± 1.0 mg P/L and >99% removal efficiency was achieved fed with synthetic high-strength phosphorus wastewater. Long-term sludge acclimation proved that the dominant polyphosphate accumulating organisms (PAOs), Candidatus Accumulibacter, could evolve to a specific subtype that can tolerate the nitrite inhibition as revealed by operational taxonomic unit (OTU)-based oligotyping analysis. The EBPR kinetic and stoichiometric evaluations combined with the amplicon sequencing proved that the Candidatus Competibacter, as the dominant glycogen accumulating organisms (GAOs), could well coexist with PAOs (15.3-24.9% and 14.2-33.1%, respectively) and did not deteriorate the EBPR performance. The nitrification activity assessment, amplicon sequencing, and functional-based gene marker quantification verified that the unexpected nitrite accumulation (10.7-21.0 mg N/L) in the high-strength EBPR system was likely caused by the nitritation process, in which the nitrite-oxidizing bacteria (NOB) were successfully out-selected (<0.1% relative abundance). We hypothesized that the introduction of the anaerobic phase with high VFA concentrations could be the potential selection force for achieving nitritation based on the literature review and our preliminary batch tests. This study sheds light on developing a new feasible technical route for integrating EBPR with short-cut nitrogen removal for efficient high-strength wastewater treatment.

Microbiological parameters as an indicator of acrogenic transformation of medium solonetz by forage crop rotations

Vast territories of Western Siberia (about 40%) are saline. On such lands, perennial grasses - phytomeliorants are mainly grown. The article presents the results of a four-year study of plant-microbial interactions in medium-sodium solonetz under fodder crop rotations with sweet yellow clover and awnless brome. The studies were conducted in the Baraba lowland, where crop rotations using layer-by-layer tillage were cultivated at the SSRIF (Siberian Scientific Research Institute of Feed) station for 33 years. In a six-field crop rotation with sweet clover in the first field, sweet clover of the Alsheevsky variety was sown with a cover crop – Sudan grass of the Novosibirskaya 84 variety; the second field was occupied by sweet clover; the third field was planted with Krasnoobsky oats. After that, everything was repeated all over again. In the crop rotation with rump, millet Kormovoe 45 was buried in the first field; in the second field, an awnless brome cultivar of the Siberian Scientific Research Institute of Agriculture -189 and millet were planted. Then the rump grew for four years. As a result of tillage and long-term exposure to phytomeliorant herbs in the 0–20 cm layer of medium solonetz, the biodiversity of bacteria has changed, the nitrification activity of the soil has increased by 1.9–2.3 times (primarily affecting the productivity of grasses cultivated in crop rotations). Under the sweet clover, the process of microbiological humus accumulation was activated. Using metagenomic analysis of 16S rRNA, four taxonomic groups of bacteria (phyla) were identified, significantly different from the virgin soil. In both crop rotations in the average solonetz, under the influence of agrobiological reclamation, the proportion of bacteria of the phylum firmicutes, mineralises of complex nitrogen-containing substances and producers of plant growth stimulants, as well as beta- and deltaproteobacteria, functionally associated with improving soil fertility, increased. Under the rump, the representation of Chloroflexi, indicators of soil density, significantly decreased.

Effects of potassium monopersulfate on nitrification activity and bacterial community structure of sponge biocarrier biofilm in Litopenaeus vannamei aquaculture system

ABSTRACT Effects of potassium monopersulfate (KMPS) on the nitrification activity, aquacultural water quality and bacterial community structure of sponge biocarriers with pre-cultured biofilm (SBBF) were analysed through shaking flask experiments and L. vannamei aquaculture experiments. Changes in the ammonia oxidation rate (AOR) and nitrite oxidation rate (NOR) of SBBF under six KMPS concentration treatments (0, 1, 2, 3, 4 and 5 mg/L) were studied. The results showed that the AOR and NOR of SBBF treated with high concentrations of KMPS (3, 4 and 5 mg/L) were significantly lower than those of the control group (CK) (p < 0.05). However, compared with the first dosing of NH4Cl and NaNO2, the inhibition of AOR and NOR by KMPS on AOR and NOR was weakened after the second and third dosing times. That is, AOR and NOR can recover partially or completely over time. The L. vannamei aquaculture experiment was performed using four concentrations of KMPS (0, 2, 4 and 8 mg/L). The results showed that with increasing KMPS dosage, the average and peak concentrations of NH4 +-N and NO2 –-N in each treatment significantly increased (P < 0.05), and the final body weight of shrimp significantly decreased (P < 0.05). Furthermore the highest dose (8.0 mg/L) of KMPS reduced the survival rate by 9.33% compared to the CK. High-throughput sequencing analysis of the biofilm structure showed that the relative abundances of Nitrospirota, Nitrosomonas and Nitrococcus, which are related to nitrogen cycling, and beneficial bacteria including Firmicutes and Bacilli decreased with the addition of KMPS (p < 0.05).

Review of experimental biodegradation data on pharmaceuticals and comparison with predictive BIOWIN models

In this study the experimental data on the biodegradation of 16 pharmaceuticals in activated sludge were reviewed and also the theoretical biodegradation of these pharmaceuticals was calculated using BIOWIN models. The main aim was to show the similarities or discrepancies between the two. Experimental data were critically reviewed considering biodegradation rates, biodegradation mechanisms and biosorption of pharmaceuticals. For some pharmaceuticals, theoretical BIOWIN estimations and experimental findings deviated from each other. For example, if only BIOWIN estimations are considered, clarithromycin, azithromycin and ofloxacin would be defined as refractory. However, in experimental studies, they appeared to be not completely refractory. One of the reasons is that in most cases pharmaceuticals could be used as secondary substrates in the presence of sufficient bulk organic matter. In addition, all experimental studies indicate that at long Solids Retention Times (SRTs), nitrification activity becomes enhanced and the enzyme AMO leads to the cometabolic elimination of many pharmaceuticals. BIOWIN models prove to be very helpful for having an initial idea about biodegradability of pharmaceuticals. However, in order to estimate the biodegradability under real conditions, the models can be extended to include the different removal mechanisms reported in this study.

Salinity changes the nitrification activity and community composition of comammox Nitrospira in intertidal sediments of Yangtze River estuary.

The newly discovered complete ammonia-oxidizing (comammox) Nitrospira has been identified in different environments, including coastal environments, where salinity is one of the most important factors for the abundance and activity of nitrifiers. Here, we demonstrate the effect of salinity on comammox Nitrospira, canonical ammonia-oxidizing bacteria (AOB), and ammonia-oxidizing archaea (AOA) in the intertidal sediments of the Yangtze River estuary based on microcosm experiments, DNA stable-isotope probing (DNA-SIP), and potential ammonium-oxidation rate (PAR) tests for different groups of ammonia oxidizers with selective inhibitors. During microcosm incubations, the abundance of comammox Nitrospira was more sensitive to increased salinity than that of other ammonia oxidizers. The results obtained with DNA-SIP heavy fractions showed that the dominant phylotype in clade A.2 (containing genes involved in the adaptation to haloalkaline environments) had high proportions in comammox Nitrospira community under both freshwater (0.06% salinity) and highly saline water (3% salinity) conditions. In contrast, another phylotype of clade A.2 (which lacks these genes) was dominant only under freshwater conditions. The PARs confirmed that comammox Nitrospira presented greater contributions to nitrification under freshwater conditions with a PAR of 4.37 ± 0.53 mg N·day-1·kg soil-1 (54%) than under saline water conditions with a PAR of 0.60 ± 0.94 mg N·day-1·kg soil-1 (18%). Moreover, AOA were specific to saline water conditions, whereas AOB were common under both freshwater and saline water conditions (44% and 52%, respectively). The present study provided evidence that salinity markedly affects the activity of comammox Nitrospira, and that the salt sensitivity of different phylotypes varies. IMPORTANCE Complete ammonia oxidation (comammox) is a newly discovered type of nitrification through which ammonia is oxidized to nitrate in an organism. Comammox Nitrospira were abundantly found in coastal ecosystems and demonstrated high community diversity. Changes in salinity are considered one of the most important factors to comammox Nitrospira in coastal ecosystems; however, reports on the correlation between them remain inconsistent. Therefore, it is critical to experimentally determine the influence of salinity on comammox Nitrospira in the coastal ecosystem. This study demonstrated a clear effect of salinity on the abundance, activity, and relative contribution of different ammonia oxidizers, especially for comammox Nitrospira. To the best of our knowledge, this is the first study demonstrating comammox Nitrospira activity at seawater salinities, implying the existence of a salt-tolerant type comammox Nitrospira, despite its activity being much lower than in freshwater conditions. The indicated correlation between the activity of specific comammox Nitrospira and salinity is anticipated to provide insights into the distribution of comammox Nitrospira and their potential contributions in estuaries and coastal ecosystems.

On the question of the mechanism of the general toxic action of lead nitrate

The leading unfavorable factor in the working environment that affects the health of miners is polymetallic dust, which contains a large number of toxic chemical elements. The study of the chemical composition of the floating dust in the air environment of the quarries of the East Kazakhstan copper-chemical plant and processing plant (Mamyrbaev, Konakbaev, 1992) showed a high content of lead, selenium, antimony, arsenic, and other trace elements.

Molybdoenzymes isolated from S. glanis liver can produce nitric oxide from nitrates and nitrites

Nitric oxide (NO) plays numerous essential physiological functions in terrestrial animals. In mammals, NO production from l-arginine is catalysed by the enzyme NO synthase (NOS). In recent years, data have begun to emerge on NOS expression and the physiological significance of NO in ectothermic vertebrates such as fish. However, there are relatively fewer data compared to the mammalian system. Although it is already well known that animal molybdoenzymes can convert nitrate and nitrite into NO, there is almost no information on the content and properties of molybdoenzymes in fish organs in the scientific literature. In this regard, the objectives of the present work were to detect the activity of classical molybdoenzymes xanthine oxidase (XO) and aldehyde oxidase (AO) in the liver and to study their possible activity to reduce nitrate and nitrite to nitrogen monoxide. In this work, the intrinsic activity of XO and AO was examined by using their substrates. At the same time, their nitrate (NR) – and nitrite reductase (NiR) activity were determined. It was determined that XO and AO in the fish liver are mainly represented by the molybdenum-free forms. The presence of an additional source of molybdenum can activate both the intrinsic and the NR and NiR activities. The NiR activity of XO and AO was higher than their NR activity. The data shows that treatment at a concentration of sodium molybdate and glutathione of 1.0 mM increases all activities of XO and AO. The optimal conditions for maximum activation of exogenous molybdate for XO and AO were reached by heating at 70 °C for 5 minutes. The activity of XO increased almost 4.7 times, and the activity of AO 7.7 times compared with its intrinsic activity without heat treatment. NO is formed from nitrite by the enzymes XO and AO much more than from nitrate.

Optimal Concentration and Duration of Endotracheal Tube Coating to Achieve Optimal Antimicrobial Efficacy and Safety Balance: An In Vitro Study

Ventilator-associated pneumonia (VAP) is a common and genuine complication in fundamentally sick patients accepting mechanical ventilation. Silver nitrate sol-gel (SN) has been proposed as a potential preventative measure against VAP. Be that as it may, the arrangement of SN with distinctive concentrations and pH values remains a basic factor influencing its effectiveness. Silver nitrate sol-gel was arranged with distinctive concentrations (0.1852%, 0.03496%, 0.1852%, and 0.01968%) and pH values (8.5, 7.0, 8.0, and 5.0) separately. The antimicrobial action of the silver nitrate and NaOH arrangements were assessed against Escherichia coli as a reference strain. The thickness and pH of the arrangements were measured, and biocompatibility tests were performed on the coating tube. The auxiliary changes in the endotracheal tube (ETT) tests after treatment were analyzed utilizing electron microscopy (SEM) and transmission electron microscopy (TEM). The pH estimations of the diverse arrangements showed that the pH values shifted depending on the test conditions, with pH values extending from 5.0 to 8.5. The consistency estimations of the arrangements showed that the thickness values expanded as the pH values drew closer to 7.5 and diminished when the pH values went over 7.5. The antimicrobial action of the silver nitrate and NaOH arrangements were successful against Escherichia coli, with microbial checks decreasing in concentration (0.03496%, 0.1852% (pH: 8), and 0.01968%). The biocompatibility tests revealed tall cell reasonability rates, demonstrating that the coating tube was secure for therapeutic utilization and did not hurt typical cells. The SEM and TEM investigation gave visual proof of the antibacterial impacts of the silver nitrate and NaOH arrangements on the bacterial surface or interior of the bacterial cells. Moreover, the investigation revealed that a concentration of 0.03496% was the foremost successful in hindering the development of ETT bacterial colonization at the nanoscale level. We propose that cautious control and alteration of the pH and thickness of the arrangements are essential to guaranteeing the reproducibility and quality of the sol-gel materials. The silver nitrate and NaOH arrangements may serve as a potential preventative degree against VAP in sick patients, with a concentration of 0.03496% appearing to show the most elevated viability. The coating tube may serve as a secure and viable preventative measure against VAP in sick patients. Further investigation is required to optimize the concentration and introduction time of the arrangements to maximize their adequacy in avoiding VAP in real-world clinical settings.