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Purpose: Reduce the climate cost of plastic mulch is an important issue for the sustainable development of dryland. Previous studies suggest plastic mulch has risk to increase nitrous oxide emission, but how this produced by the complex interaction between soil properties and microbial is still an unsolved problem and need to research to develop targeted practice. Methods: To address this question, molecular ecology tools, including real-time quantitative and high-throughput sequencing were employed to explore how plastic mulch induced change on soil environment and then stimulates denitrification. Three mulching treatments were compared, including no mulching, spring and autumn mulching. Results: Plastic mulch induced significant increase in the richness and diversity of nir-containing denitrifiers. The nirS and nirK-gene abundance was the greatest under the autumn mulching, and a more conspicuous change in the community structure and abundance was observed for nirK gene than for nirS denitrifiers. The most differentially abundant taxa in the autumn mulching were Anaeromyxobacter, Terriglobus, Edwardsiella, Catenulispora and Acidobacterium for nirK genes and Cupriavidus for nirS genes. Mulching increased the potential denitrification enzyme activity by 58% and 29% for autumn and spring mulching, respectively, and this effect was mirrored by the abundance of nirK, but not by nirS denitrifiers. The nirK gene was significantly correlated to variations in soil moisture, temperature, and nitrate nitrogen. Conclusion: Plastic mulch stimulates denitrification by inducing higher moisture, temperature and nitrate nitrogen content and structural change in the community of nirK denitrifying bacteria in dryland agroecosystems. [ABSTRACT FROM AUTHOR]

Non-fermentative nitrite reduction to ammonium, resulting in the release of ammonium in the environment, can be performed by a variety of enzymes found among bacteria and archaea. NrfA-dependent ammonifiers are phylogenetically diverse and are present in terrestrial and aquatic environments, and for the latter especially in sediments. NrfA-dependent ammonifiers often carry genes involved in denitrification and redox reactions with sulfur or iron compounds, suggesting that they play a role in multiple biogeochemical cycles. In most aquatic and terrestrial environments, denitrifiers dominate over nitrate ammonifiers, and denitrification is the dominating process of nitrate reduction. However, nitrate ammonification rates can be significant under certain redox conditions. Nitrate ammonifiers are a taxonomically diverse group of microorganisms that reduce nitrate to ammonium, which is released, and thereby contribute to the retention of nitrogen in ecosystems. Despite their importance for understanding the fate of nitrate, they remain a largely overlooked group in the nitrogen cycle. Here, we present the latest advances on free-living microorganisms using NrfA to reduce nitrite during ammonification. We describe their diversity and ecology in terrestrial and aquatic environments, as well as the environmental factors influencing the competition for nitrate with denitrifiers that reduce nitrate to gaseous nitrogen species, including the greenhouse gas nitrous oxide (N 2 O). We further review the capacity of ammonifiers for other redox reactions, showing that they likely play multiple roles in the cycling of elements. [ABSTRACT FROM AUTHOR]

Most reduced organic matter entering activated sludge systems is particulate (1–100-µm diameter) or colloidal (0.001–1-µm diameter), yet little is known about colonization of particulate organic matter by activated sludge bacteria. In this study, colonization of biopolymers (chitin, keratin, lignocellulose, lignin, and cellulose) by activated sludge bacteria was compared with colonization of glass beads in the presence and absence of regular nutrient amendment (acetate and ammonia). Scanning electron microscopy and quantitative PCR revealed chitin and cellulose were most readily colonized followed by lignin and lignocellulose, while keratin and glass beads were relatively resistant to colonization. Bacterial community profiles on particles compared to sludge confirmed that specific bacterial phylotypes preferentially colonize different biopolymers. Nitrifying bacteria proved adept at colonizing particles, achieving higher relative abundance on particles compared to bulk sludge. Denitrifying bacteria showed similar or lower relative abundance on particles compared to sludge. Key points: • Some activated sludge bacteria colonize natural biopolymers more readily than others. • Nitrifying bacteria are overrepresented in natural biopolymer biofilm communities. • Biopolymers in wastewater likely influence activated sludge community composition. [ABSTRACT FROM AUTHOR]

During pregnancy, all major physiological systems undergo remarkable changes, driven largely by alterations in the maternal hormonal milieu. In healthy pregnancies, maternal cardiovascular and metabolic adaptation to pregnancy occurs to support fetal growth and maternal well-being. Impaired maternal adaptation to pregnancy is associated with a range of pregnancy complications, including gestational diabetes and preeclampsia. There is growing recognition of the importance of different maternal microbiota, including in the gut, vagina and oral cavity, in supporting normal maternal adaptations to pregnancy as well as evidence for microbial disturbances associating with pregnancy pathologies. Here, we aim to summarise emerging evidence demonstrating that differences in maternal microbiota associate with pregnancy outcomes and discuss potential therapeutic approaches under development that might restore an 'optimal' microbiome. In particular, we highlight recent work by ourselves and others exploring the role of the oral microbiome in pregnancy, given established links between poor oral health (e.g. periodontitis) and adverse pregnancy outcomes. Our research has focussed on specific nitrate-reducing oral bacteria which play a role in the generation of nitric oxide (NO) and other bioactive nitrogen oxides associated with cardiovascular health and maternal cardiovascular adaption to pregnancy. Ongoing research aims to define whether altered microbial profiles have clinical utility in the prediction of pregnancy pathologies, and whether interventions designed to optimise specific maternal microbiota could help prevent future complications. [ABSTRACT FROM AUTHOR]

The primary objective of the present study is to enhance the denitrification process in constructed wetlands (CWs), employed as an ecological and natural technology for wastewater treatment. Eco-friendly approaches have been tested to improve the nitrate removal efficiency in pilot-scale subsurface flow CWs. Initially, the system's performance was enhanced by using a natural substrate, namely cork, as a filter medium. Another approach is bio-inoculation into the rhizosphere of a bacterial strain with the potential capacity for nitrate removal, thereby reinforcing the synergy between the plant and microorganisms. Finally, the approaches were combined, and nitrate removal was assessed. The main results showed that the most effective nitrate removal from wastewater was achieved with cork (80%) compared to gravel (60%). Bio-inoculation into the rhizosphere of denitrifying bacteria significantly improved nitrate removal. Indeed, the nitrate removal rate by the inoculated CW filled with gravel, was higher than the non-inoculated system, with rates of 78% and 60%, respectively. Moreover, the highest removal rate of 99.77% was obtained with the inoculated system filled with cork. [ABSTRACT FROM AUTHOR]

The single-cycle transient high-concentration organic load shock test was conducted on the micropressure swirl reactor (MPSR) and sequencing batch reactor (SBR) to assess their capability to different levels of transient organic load shock (OLS), including pollutant removal, sludge characteristics, and microbial characteristics. The results indicated that the impact-resistance of biological treatment systems was related to reactor structure and microbial community distribution. When subjected to transient chemical oxygen demand (COD) load of 0.81, 1.28, and 1.70 g / (L · d a y) , respectively, both reactors exhibited effective organic removal capabilities. Compared with MPSR, within a certain shock range, nitrification in the SBR was less affected by shock and had a higher effect on nitrogen and phosphorus removal. However, when shock load reached 1.70 gCOD/(L·day) , the denitrification was sufficient in the MPSR, and microorganisms continued to secrete polysaccharides (PS), which was beneficial for adsorbing pollutants and resisting impacts. Under steady-state conditions, the SBR exhibited excellent nitrification with a relative abundance of 60.7% for nitrifying functional groups such as Thiothrix. Compared with the SBR, the MPSR displayed a higher microbial community diversity, with a variety of phosphorus-removing bacteria and denitrifying bacteria genera occupying aerobic and anoxic partitions within the same space, which was profitable for effective denitrification and phosphorus removal under high OLS. Besides, the enrichment of Flavobacterium and Zoogloea sp. at high concentrations significantly enhanced the MPSR's resistance to OLS. This study provides a theoretical basis for effective measures by different processes in response to organic load shocks. [ABSTRACT FROM AUTHOR]

Denitrification and nitrate-ammonification are the responsible processes for nitrate removal in the estuaries. Temperature, nitrate and organic carbon availability are key factors controlling a rate of the nitrate reduction processes. This mixed cultures chemostat study investigates the competition ability and their nitrate reduction end-products of the bacteria isolated from an estuary at different temperatures. This study will help us to understand the seasonal nitrate reduction processes in an estuary. The experiments showed that a nitrate-ammonifier was the predominant process in the steady-state chemostat at high temperature. While a facultative denitrifier-nitrate ammonifier was the predominant process at low temperature. However, the main end products of nitrate reduction at high temperature were up to 61% N2 indicating a denitrifier still had an important role in the end products of nitrate reduction in the estuary. The data also showed that a nitrite respiring bacterium reduced nitrite to N2, that responsible for approximately 6-9% of total N2 produced in the culture. This study confirmed that nitrate ammonifiers out-compete denitrifiers at high temperature, however, denitrifiers still had an important role in end products of nitrate reduction. [ABSTRACT FROM AUTHOR]

Denitrifying bacteria harboring the nitrate reductase S (nirS) gene convert active nitrogen into molecular nitrogen, and alleviate eutrophication in aquaculture water. Suspended particulate matter (SPM) is an important component of aquaculture water and a carrier for denitrification. SPM with different particle sizes were collected from a coastal high-altitude aquaculture pond in Maoming City, China. Diversity, community structure, abundance of nirS-type denitrifying bacteria on SPM and environmental influencing factors were studied using high-throughput sequencing, fluorescence quantitative PCR, and statistical analysis. Pseudomonas, Halomonas, and Wenzhouxiangella were the dominant genera of nirS-type denitrifying bacteria on SPM from the ponds. Network analysis revealed Pseudomonas and Halomonas as the key genera involved in the interaction of nirS-type denitrifying bacteria on SPM in the ponds. qPCR indicated a trend toward greater nirS gene abundance in progressively larger SPM. Dissolved oxygen, pH, temperature, and SPM particle size were the main environmental factors influencing changes in the nirS-type denitrifying bacterial community on SPM in coastal high-altitude aquaculture pond water. These findings increase our understanding of the microbiology of nitrogen cycle processes in aquaculture ecosystem, and will help optimize aquatic tailwater treatment strategies. [ABSTRACT FROM AUTHOR]

Denitrification is a key process in soil available nitrogen (N) loss. However, the effects of different water-saving irrigation systems on soil N components and denitrifying bacterial communities are still unclear. In this study, quantitative fluorescence PCR and Illumina MiSeq sequencing were used to investigate the effects of three main irrigation systems, conventional flooding irrigation (FP), shallow buried drip irrigation (DI), and mulched drip irrigation (MF), on the abundance, community composition, and diversity of soil nirK- and nirS-type denitrifying bacteria in the semi-arid area of Northeast China, and to clarify the driving factors of nirK- and nirS-type denitrifying bacterial community variations. The results showed that, compared with FP, MF significantly increased soil moisture, alkaline hydrolyzed nitrogen (AHN), nitrate nitrogen (NO3−-N), non-acid hydrolyzed nitrogen (AIN), and amino sugar nitrogen (ASN), but significantly decreased the contents of ammonium nitrogen (NH4+-N) and acid hydrolyzed ammonium nitrogen (AN). The irrigation system changed the relative abundance of the dominant genera of denitrifying bacteria, DI and MF significantly increased nitrate reductase (NR) and nitrite reductase (NiR) activities, and MF significantly increased the diversity of nirK- and nirS-type denitrifying bacteria but significantly decreased the richness. The community structure of nirK- and nirS-type denitrifying bacteria was significantly different among the three irrigation systems. NO3−-N was the main driving factor affecting the community structure of nirS-type denitrifying bacteria, and moisture significantly affected the community structure of nirK-type denitrifying bacteria. DI and MF significantly increased the abundance of nirK- and nirS-type denitrifying bacteria and also increased the abundance ratio of nirS/nirK genes. Therefore, although DI and MF significantly increased the abundance of denitrifying microorganisms, they did not lead to an increase in the N2O emission potential. [ABSTRACT FROM AUTHOR]

The objective of this work is to review the main hydrogeological characteristics and to understand the hydrochemical dynamics of the denitrification process in the gravel aquifer located in the low plain of the Seybouse watershed. The methodology implemented consisted in the identification of physico-chemical indicators characterizing the denitrification phenomenon: groundwater contents in NO , SO , FeO2, and hydrogeological conditions represented by the captivity of the aquifer and the reducing environment, associated with the presence of a support rich in sulfur and denitrifying bacteria. The chemical monitoring carried out on the fourteen drillings along a South-North profile, in the direction of the underground flow, separates globally two different zones, which are positioned from the upstream to the downstream of the gravel aquifer. The first one corresponds to the oxidizing environment, located mainly in the southern part or the deep aquifer and in direct contact with the surface aquifer. [ABSTRACT FROM AUTHOR]

Denitrification is a form of anaerobic respiration wherein nitrate (NO3 -) is sequentially reduced via nitrite (NO2 -), nitric oxide, and nitrous oxide (N2O) to dinitrogen gas (N2) by four reductase enzymes. Partial denitrifying bacteria possess only one or some of these four reductases and use them as independent respiratory modules. However, it is unclear if partial denitrifiers sense and respond to denitrification intermediates outside of their reductase repertoire. Here, we tested the denitrifying capabilities of two purple nonsulfur bacteria, Rhodopseudomonas palustris CGA0092 and Rhodobacter capsulatus SB1003. Each had denitrifying capabilities that matched their genome annotation; CGA0092 reduced NO2 - to N2, and SB1003 reduced N2O to N2. For each bacterium, N2O reduction could be used both for electron balance during growth on electron-rich organic compounds in light and for energy transformation via respiration in darkness. However, N2O reduction required supplementation with a denitri fication intermediate, including those for which there was no associated denitrification enzyme. For CGA0092, NO3 - served as a stable, non-catalyzable molecule that was sufficient to activate N2O reduction. Using a β-galactosidase reporter, we found that NO3 - acted, at least in part, by stimulating N2O reductase gene expression. In SB1003, NO2 - but not NO3 - activated N2O reduction, but NO2 - was slowly removed, likely by a promiscuous enzyme activity. Our findings reveal that partial denitrifiers can still be subject to regulation by denitrification intermediates that they cannot use. [ABSTRACT FROM AUTHOR]

In this work, the transformation law of nitrogen in sediment–water system under different flow rates and wastewater concentrations were investigated in a simulated sewage pipeline system. Results showed that the different flow rates and wastewater concentrations in the pipeline caused differences in microbial community in sediments and nitrogen transformation. When the flow rate increased from 0.05 to 0.2 m/s, the scouring effect was enhanced, resulting in higher concentrations of NH4+–N and NO3−–N in the overlying water. At 0.2 m/s, the relative abundance of Clostridium_sensu_stricto_1 in sediments was higher, resulting in a greater conversion of amino acid nitrogen (AAN) to NH4+–N. Meanwhile, many denitrifying bacteria (Trichococcus, Dechloromonas, norank_f__norank_o__Gaiellales, Thiobacillus) had high relative abundance in the sediments, and the denitrification process was common. When the wastewater concentration was high, the nitrification reaction was great in overlying and interstitial water. Moreover, the ammoniation process was great in the sediments, and the variation flux of AAN was large (remarkably reduced). Practitioner Points: AAN transformed to NH4+–N in sediment under different flow rate and concentration.Scouring was enhanced at 0.2 m/s, increasing nitrogen contents in overlying water.Difference in microbial community led to more AAN conversion to NH4+–N at 0.2 m/s.The ammoniation process was greater in sediment at a high concentration of sewage.NH4+–N migrated from overlying water to sediment at a high concentration of sewage. [ABSTRACT FROM AUTHOR]

Filamentous algae blooms (FABs) have been increasing globally in recent years, and their presence can have both harmful and beneficial effects on aquatic ecosystems. As one of the most common FABs, Cladophora blooms have been reported in the lakes of the Qinghai-Tibet Plateau during the past few years. However, there have been few studies focused on how FABs impact other aquatic organisms, especially in alpine lakes since these are at the forefront of responding to global climate change. In this study, the phytoplankton communities in different regions of Qinghai Lake were profiled in different seasons using meta-barcode sequencing. The phytoplankton assemblages in areas with Cladophora blooms were compared to those without Cladophora. The phytoplankton community structure correlated with physicochemical properties including water temperature, electrical conductivity, nitrate, and the presence or absence of Cladophora blooms. The relative abundance of Bacillariophytes was found to be higher in zones with Cladophora blooms than in other regions. Significant seasonal changes in phytoplankton biomass and β diversity were observed in zones with Cladophora blooms. Growth and microbial degradation of Cladophora can change the pH, dissolved oxygen, secchi depth, and nitrate. Together with seasonal temperature and electrical conductivity changes, Cladophora growth can significantly impact the phytoplankton biomass, community dissimilarity and assembly process. These results showed that Cladophora plays a key role in littoral aquatic ecosystem ecology. [ABSTRACT FROM AUTHOR]

In the field of wastewater treatment, nitrate nitrogen (NO3−-N) is one of the significant contaminants of concern. Sulfur autotrophic denitrification technology, which uses a variety of sulfur-based electron donors to reduce NO3−-N to nitrogen (N2) through sulfur autotrophic denitrification bacteria, has emerged as a novel nitrogen removal technology to replace heterotrophic denitrification in the field of wastewater treatment due to its low cost, environmental friendliness, and high nitrogen removal efficiency. This paper reviews the advance of reduced sulfur compounds (such as elemental sulfur, sulfide, and thiosulfate) and iron sulfides (such as ferrous sulfide, pyrrhotite, and pyrite) electron donors for treating NO3−-N in wastewater by sulfur autotrophic denitrification technology, including the dominant bacteria types and the sulfur autotrophic denitrification process based on various electron donors are introduced in detail, and their operating costs, nitrogen removal performance and impacts on the ecological environment are analyzed and compared. Moreover, the engineering applications of sulfur-based electron donor autotrophic denitrification technology were comprehensively summarized. According to the literature review, the focus of future industry research were discussed from several aspects as well, which would provide ideas for the application and optimization of the sulfur autotrophic denitrification process for deep and efficient removal of NO3−-N in wastewater. [ABSTRACT FROM AUTHOR]

• Pioneering application of Mn2+-based catalytic ozonation conditioning to in-situ sludge reduction. • Doubled the MLSS reduction rate in sludge and a 19% decrease in observed sludge yield. • Significant increase in peak dehydrogenase activity from 143.83 to 176.41 mg TF/g TSS·hr. • An 18% promotion in the maximum utilization of carbon sources by microorganisms. • Enhancement of sludge reduction and solubilization dominated by Defluviicoccus and Ferruginibacter. To improve the sludge conditioning efficiency without increasing the ozone dose, an in-situ sludge reduction process based on Mn2+-catalytic ozonation conditioning was proposed. Using ozone conditioning alone as a control, a lab-scale sequencing batch reactor coupled with ozonated sludge recycle was evaluated for its operating performance at an ozone dose of 75 mg O 3 /g VSS and 1.5 mmol/L Mn2+ addition. The results showed a 39.4% reduction in MLSS and an observed sludge yield of 0.236 kg MLSS/kg COD for the O 3 +Mn2+ group compared to the O 3 group (15.3% and 0.292 kg MLSS/kg COD), accompanied by better COD, NH 4 +-N, TN and TP removal, improved effluent SS and limited impact on excess sludge properties. Subsequently, activity tests, BIOLOG ECO microplates and 16S rRNA sequencing were applied to elucidate the changing mechanisms of Mn2+-catalytic ozonation related to microbial action: (1) Dehydrogenase activity reached a higher peak. (2) Microbial utilization of total carbon sources had an elevated effect, up to approximately 18%, and metabolic levels of six carbon sources were also increased, especially for sugars and amino acids most pronounced. (3) The abundance of Defluviicoccus under the phylum Proteobacteria was enhanced to 12.0% and dominated in the sludge, they had strong hydrolytic activity and metabolic capacity. Denitrifying bacteria of the genus Ferruginibacter also showed an abundance of 7.6%, they contributed to the solubilization and reduction of sludge biomass. These results could guide researchers to further reduce ozonation conditioning costs, improve sludge management and provide theoretical support. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, two types of woodchip-amended biosand filters (Filter A sand: woodchip = 33%: 67% versus Filter B sand: woodchip = 50%: 50%, by volume) were constructed, and their abilities to remove MS2 bacteriophage and nitrate were investigated. The results indicated that Filter A and Filter B could reduce nitrate up to 40 and 36%, respectively, indicating that the nitrate reduction increased with the increase in woodchip proportion. The study underscores a positive correlation between nitrate reduction and proportional increase in woodchip content, implying the potential for fine-tuning nitrate removal by varying sand-woodchip compositions. W-BSFs could remove MS2 bacteriophage to 1.91-log10 (98.8%) by Filter A and 1.88-log10 (98.7%) by Filter B over 39 weeks. The difference in sand-woodchip proportion did not significantly impact the MS2 reduction, demonstrating that a single W-BSF can maintain its virus removal performance fairly well over a long-term period. These results indicated that the nitrate reduction could be adjusted by varying sand-woodchip contents without impacting virus removal performance. Microbial community analysis indicated that the nitrate removal by the W-BSFs could be attributed to the denitrifying bacteria, such as the family Streptomycetaceae, the genera Pseudomonas, and Bacillus, and relative abundances of the phylum Nitrospirae. [ABSTRACT FROM AUTHOR]

The nitrate (NO3-) reducing bacteria resident in the oral cavity have been implicated as key mediators of nitric oxide (NO) homeostasis and human health. NO3--reducing oral bacteria reduce inorganic dietary NO3- to nitrite (NO2-) via the NO3--NO2--NO pathway. Studies of oral NO3--reducing bacteria have typically sampled from either the tongue surface or saliva. The aim of this study was to assess whether other areas in the mouth could contain a physiologically relevant abundance of NO3- reducing bacteria, which may be important for sampling in clinical studies. The bacterial composition of seven oral sample types from 300 individuals were compared using a meta-analysis of the Human Microbiome Project data. This analysis revealed significant differences in the proportions of 20 well-established oral bacteria and highly abundant NO3--reducing bacteria across each oral site. The genera included Actinomyces, Brevibacillus, Campylobacter, Capnocytophaga, Corynebacterium, Eikenella, Fusobacterium, Granulicatella, Haemophilus, Leptotrichia, Microbacterium, Neisseria, Porphyromonas, Prevotella, Propionibacterium, Rothia, Selenomonas, Staphylococcus, Streptococcus and Veillonella. The highest proportion of NO3--reducing bacteria was observed in saliva, where eight of the bacterial genera were found in higher proportion than on the tongue dorsum, whilst the lowest proportions were found in the hard oral surfaces. Saliva also demonstrated higher intra-individual variability and bacterial diversity. This study provides new information on where samples should be taken in the oral cavity to assess the abundance of NO3--reducing bacteria. Taking saliva samples may benefit physiological studies, as saliva contained the highest abundance of NO3- reducing bacteria and is less invasive than other sampling methods. These results inform future studies coupling oral NO3--reducing bacteria research with physiological outcomes affecting human health. [ABSTRACT FROM AUTHOR]

Nitrogen pollution in water bodies presents a serious threat to ecosystems due to its role in eutrophication. In this study, the aerobic denitrifying bacterium Alcaligenes faecalis was used as a model microorganism to investigate the optimal operating conditions for nitrogen removal from nitrogen-containing wastewater by Alcaligenes faecalis under different aeration modes, microbial dosages and C/N ratios. The results showed that the optimal aeration mode for efficient bacterial denitrification was 10 min of aeration with a 30 min interval, and the total nitrogen removal reached 87.82%. At different bacterial doses, NO3−–N was completely denitrified and NO2−–N accumulation levels were reduced, all of which resulted in significant denitrification, and the final total nitrogen removal efficiencies reached 86.39–98.50%. With an increase in the C/N ratio, the pollutant removal performance of denitrifying bacteria increased. When the C/N ratio was 17, the final rates of NO3−–N, TN and COD removal were 100%, 98.50% and 96.13%, respectively. At lower C/N ratios, the growth and metabolism of microorganisms were inhibited and fewer electron acceptors were available during the denitrification process, which seriously affected denitrification performance. In this study, the denitrification performance of aerobic denitrifying bacterium Alcaligenes faecalis was explored in experiments using changes in aeration mode, microbial dosage and C/N ratio, and the optimal operating conditions of Alcaligenes faecalis for treating nitrogenous wastewater were indicated. This provides technical support for Alcaligenes faecalis in improving the remediation effect of nitrogenous wastewater and provides a theoretical basis for further in-depth research on the performance of Alcaligenes faecalis in the future. [ABSTRACT FROM AUTHOR]

BACKGROUND: Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms have been shown to influence serum levels of homocysteine, Vit B12 and Folate. Homocysteine has been implicated as a cataractogenic stressor while reduced serum levels of Vit B12 and Folate have been found to be associated with cataract cases. OBJECTIVE: To investigate the associations of MTHFR C677T gene polymorphisms, serum homocysteine levels, serum Vit B12 and serum folate levels in patients with age related cataract. PATIENTS AND METHODS: This study was carried out in Eye Department of Swami Dayanand Hospital. Dilshad Garden, Delhi from 1st December 2020 till 30th September 2021 as a case cohort study. 40 cases with cataract and 40 healthy individuals without cataract were enrolled. Informed consent and detialed history were obtained from all participants and a comprehensive examination was done. They were subjected to estimation of MTHFR gene (C667T) polymorphism, Serum Homocysteine, Vitamin B12 and Folic acid and all the biochemical tests were carried out at Institute of Human Behavior and Allied Sciences (IHBAS), Delhi. RESULTS: This study included a total of 40 cases with cataract and 40 matched controls with mean age of 57.65±6.52 and 55.45±4.67 years respectively. We observed no significant difference in serum homocysteine, folic acid and vitamin B 12 levels between cases and controls. However, MTHFR C677T gene polymorphism in cataract cases were significantly different from that of controls (p=0.03). CONCLUSION AND RELEVANCE: This study is the first to investigate genetic association of MTHFR gene polymorphism with age related cataract in a subset of Indian population. Statistically significant difference of MTHFR C677T gene polymorphism in cataract cases and control was observed. If this finding is supported by future research with larger sample sizes, high quality, and broader ethnicity coverage, then MTHFR C677T gene polymorphism may represent new candidate biomarkers for high-risk ARC population. [ABSTRACT FROM AUTHOR]

Microbial vanadate [V(V)] reduction is the key process of vanadium geochemical cycling, while the identified functional microbes are rather limited. Considering the structural similarity of metavanadate and nitrate, widespread denitrifying bacteria are expected to be able to mediate V(V) reduction, but this process has not been fully understood. This study confirmed the effectiveness of two denitrifying bacteria, i.e., Acidovorax sp. strain BoFeN1 and Pseudogulbenkiania sp. strain 2002, in reducing V(V). During 120-h incubation, the V(V) removal efficiency was 89.0 ± 1.83% and 96.0 ± 1.43% by strain BoFeN1 and strain 2002, respectively. V(V) was reduced to tetravalent vanadium [V(IV)] both intracellularly and extracellularly. Use of inhibitors and metabolomic analysis revealed enzyme catalysis and electron transfer pathways for V(V) reduction. Enzyme catalysis was identified by analyses of gene abundance, transcript abundance, and enzymatic activity. Electron transfer was verified through quantifying electron transporters, monitoring electron transport system activity, and performing cyclic voltammetry analysis. For strain BoFeN1, nitrite and nitrous oxide reductases played vital roles in V(V) reduction, together with cytochrome c (Cyt c) and nicotinamide adenine dinucleotide (NADH) mediated electron transfer. Differentially expressed riboflavin produced by strain BoFeN1 also promoted electron transfer. Strain 2002 mainly utilized periplasmic nitrate reductase to reduce V(V). Aquifer sediment bioaugmented with these strains enhanced V(V) reduction by 10.5%−51.1%. They well colonized and collaborated with indigenous microorganisms to reduce V(V) to V(IV). This study advances understanding of environmental biogeochemistry of vanadium and provides molecular insights into V(V) bio-reduction as a sustainable bioremediation strategy. [ABSTRACT FROM AUTHOR]

The impacts of changes in hydraulic retention time (HRT) on nitrogen elimination, the activity of sludge and the structure of microbial communities in a sequencing batch reactor under the joint stress of ibuprofen (IBP) and ciprofloxacin (CIP) were investigated. Under the combined stress of IBP (belonged to nonsteroidal anti-inflammatory drugs) and CIP (belonged to antibiotics), the elimination level of ammonia nitrogen, chemical oxygen demand, and the rate of specific ammonia oxidation, specific nitrite oxidation, specific nitrate reduction in activated sludge declined with the shortening of HRT. Under the joint stress of IBP and CIP, the content of polysaccharide (PS) and protein (PN) together with the ratio of PN to PS in the extracellular polymeric substances grew with the shortening of HRT, and the content of aromatic proteins increased significantly, which indicated that aromatic proteins were the major protective response substances to the shortening of HRT. Under the joint stress of IBP and CIP, with the reduction of HRT, and the reduction rate of relative abundance of nitrifying bacteria was more evident than that of denitrifying bacteria. This exploration gives novel thoughts for understanding the impacts of HRT on biological nitrogen removal of wastewater under combined stress of IBP and CIP. [ABSTRACT FROM AUTHOR]

Denitrifying bacteria in epiphytic biofilms play a crucial role in nitrogen cycle in aquatic habitats. However, little is known about the connection between algae and denitrifying bacteria and their assembly processes in epiphytic biofilms. Epiphytic biofilms were collected from submerged macrophytes (Patamogeton lucens and Najas marina L.) in the Caohai Lake, Guizhou, SW China, from July to November 2020 to: (1) investigate the impact of abiotic and biotic variables on denitrifying bacterial communities; (2) investigate the temporal variation of the algae-denitrifying bacteria co-occurrence networks; and (3) determine the contribution of deterministic and stochastic processes to the formation of denitrifying bacterial communities. Abiotic and biotic factors influenced the variation in the denitrifying bacterial community, as shown in the Mantel test. The co-occurrence network analysis unveiled intricate interactions among algae to denitrifying bacteria. Denitrifying bacterial community co-occurrence network complexity (larger average degrees representing stronger network complexity) increased continuously from July to September and decreased in October before increasing in November. The co-occurrence network complexity of the algae and nirS-encoding denitrifying bacteria tended to increase from July to November. The co-occurrence network complexity of the algal and denitrifying bacterial communities was modified by ammonia nitrogen (NH4+-N) and total phosphorus (TP), pH, and water temperature (WT), according to the ordinary least-squares (OLS) model. The modified stochasticity ratio (MST) results reveal that deterministic selection dominated the assembly of denitrifying bacterial communities. The influence of environmental variables to denitrifying bacterial communities, as well as characteristics of algal-bacterial co-occurrence networks and the assembly process of denitrifying bacterial communities, were discovered in epiphytic biofilms in this study. The findings could aid in the appropriate understanding and use of epiphytic biofilms denitrification function, as well as the enhancement of water quality. [ABSTRACT FROM AUTHOR]

To better understand bacterial communities and metabolism under nitrogen deficiency, 154 seawater samples were obtained from 5 to 200 m at 22 stations in the photic zone of the Western North Pacific Ocean. Total 634 nitrate-utilizing bacteria were isolated using selective media and culture-dependent methods, and 295 of them were positive for nitrate reduction. These nitrate-reducing bacteria belonged to 19 genera and 29 species and among them, Qipengyuania flava, Roseibium aggregatum, Erythrobacter aureus, Vibrio campbellii, and Stappia indica were identified from all tested seawater layers of the photic zone and at almost all stations. Twenty-nine nitrate-reducing strains representing different species were selected for further the study of nitrogen, sulfur, and carbon metabolism. All 29 nitrate-reducing isolates contained genes encoding dissimilatory nitrate reduction or assimilatory nitrate reduction. Six nitrate-reducing isolates can oxidize thiosulfate based on genomic analysis and activity testing, indicating that nitrate-reducing thiosulfate-oxidizing bacteria exist in the photic zone. Five nitrate-reducing isolates obtained near the chlorophyll a-maximum layer contained a dimethylsulfoniopropionate synthesis gene and three of them contained both dimethylsulfoniopropionate synthesis and cleavage genes. This suggests that nitrate-reducing isolates may participate in dimethylsulfoniopropionate synthesis and catabolism in photic seawater. The presence of multiple genes for chitin degradation and extracellular peptidases may indicate that almost all nitrate-reducing isolates (28/29) can use chitin and proteinaceous compounds as important sources of carbon and nitrogen. Collectively, these results reveal culturable nitrate-reducing bacterial diversity and have implications for understanding the role of such strains in the ecology and biogeochemical cycles of nitrogen, sulfur, and carbon in the oligotrophic marine photic zone. [ABSTRACT FROM AUTHOR]

The soil microbial community diversity of wheat rhizosphere was affected by the amount of nitrogen fertilizer. In addition to bacterial community, ammonia-oxidizing archaea, nitrogen-fixing bacteria and denitrifying bacteria also play important roles in nitrogen cycle. At present, the microecological mechanism of its response to nitrogen application is still unclear. In this study, the rhizosphere soil microorganisms of winter wheat were used as the research object. The changes of soil bacteria, ammonia-oxidizing archaea, nitrogen-fixing bacteria and denitrifying bacteria communities under five nitrogen rates of 0—N(0), 90—N(6), 180—N(12), 240—N(16), 300—N(20) kg N ha–2 were studied by high-throughput sequencing technology. Under N(12) treatment, the Alpha diversity index of bacteria, AOA and nifH nitrogen-fixing bacteria and the Shannon and Simpson indices of nirK denitrifying bacteria were significantly increased. N(12) treatment significantly increased the relative abundance of Proteobacteria, but no significant difference was found at the nifH and nirK bacterial phyla levels. Under the high nitrogen treatment of N(16) and N(20), the dominant bacteria of nirK-type denitrifying bacteria increased significantly compared with N(12) treatment, there was no significant difference in microbial community distribution between N(20) and the control group. Therefore, the nitrogen addition under N(12) treatment was most conducive to the absorption and utilization of nitrogen fertilizer by soil microorganisms. The effect of nitrogen addition on microbial community was weaker than that of soil properties and wheat yield, and nitrogen addition was significantly correlated with yield, reaching the highest yield at 300 kg ha–2. [ABSTRACT FROM AUTHOR]

Cisplatin, an anticancer drug, has limited its clinical application due to its severe nephrotoxicity, such as acute kidney injury (AKI). Damaged or dysfunctional mitochondria caused by cisplatin are toxic to the cell by producing reactive oxygen species and releasing cell death factors. Mitophagy is the mechanism of selective degradation of these damaged mitochondria via autophagy, that is critical to cellular homeostasis and viability. In this study, the protective functions of inorganic nitrate against cisplatin-induced nephrotoxicity are assessed. Our results in vitro show that nitrate significantly reduced the apoptosis of HK2 or NRK52E cells induced by cisplatin treatment. Furthermore, dietary nitrate notably alleviates the tubular and glomerular damages as well as the loss of renal function in cisplatin-induced AKI mice models. These protective effects are closely related to downregulation of cell apoptosis and reduction of reactive oxygen species (ROS) generation. Mechanistically, inorganic nitrate treatment promotes the activation of mitophagy mediated by the PINK1-PRKN/PARK2 pathway, which plays an important role in the maintenance of mitochondrial quality, helping renal tubular cells to survive and recover from cisplatin stress. These novel findings suggest that inorganic nitrate supplementation deserve further exploration as a potential treatment in patients with cisplatin-induced renal injury. [ABSTRACT FROM AUTHOR]

Harmful algae blooms (HABs) can have significant adverse effects on coastal ecosystems and aquaculture resiliency. We collected samples from March to August at eight different stations in Haizhou Bay (China), a region with a high frequency of HABs, and used Illumina Novaseq high-throughput sequencing and multivariate statistical analysis to characterize the bacterial communities and their relationships with different environmental factors. We identified 27 phyla, 49 classes, 158 orders, 294 families, and 522 genera. Gammaproteobacteria, Alphaproteobacteria, Bacteroidia, Acidimicrobiia, Bacilli, Actinobacteria, Cyanobacteria, Clostridia, and Acidobacteria were the most abundant classes, and Acidobacteria, Bacteroidetes, Firmicutes, Actinobacteria, Chloroflexi, Proteobacteria, and Cyanobacteria were the keystone phyla. Based on the Mantel test and redundancy analysis, temperature was the main environmental factor affecting the structure of the bacterial communities, followed by silicate, dissolved organic phosphorus (DOP), and dissolved oxygen (DO). Among the genera with high OTU abundance, Nautella was co-related positively with DO and negatively with salinity; Planktomarina was co-related positively with salinity and negatively with nitrate and nitrite. Certain families (Flavobacteriaceae, Rhodobacteraceae, and Clade_I (SAR11 clade)) and genera (Methylophaga, Alteromonas, Oleiphilus, Marinobacter, Bacillus, Nautella, and Vibrio) had associations with phytoplankton species that were responsible for HABs. This research provides new insights into the characteristics of the bacterial communities that occur in coastal areas that have HABs and provides detailed descriptions of the spatial and temporal changes in the structure of these communities. [ABSTRACT FROM AUTHOR]

Sulphur‐driven denitrification is a low‐cost process for the treatment of nitrate‐contaminated water. However, a comprehensive understanding of core populations and microbial interactions of a sulphur‐based denitrifying system is lacking. This study presents results from three replicated denitrifying systems amended with thiosulphate and operated under a low C/N ratio. Amplicon sequencing revealed gradual enrichments of a few abundant denitrifiers. Based on genome‐centred metagenomics and metatranscriptomics, a core set of microbes was identified in the systems, with Pseudomonas 1 and Thauera 2 being the most abundant ones. Although the replicates showed different enrichments, generalized observations were summarized. Most core populations conserved energy from denitrification coupled with sulphur. Pseudomonas 1 and Thauera 2 were able to finish complete denitrification. Surprisingly, they were also able to synthesize almost all amino acids and vitamins. In contrast, less abundant members, including Pseudomonas 2, were relatively auxotrophic and required an exogenous supply of amino acids and vitamins. The high expression of enzymes involved in biosynthesis and transport systems indicated their syntrophic relationships. The genomic findings suggested life strategies and interactions of the core thiosulphate‐based denitrifying microbiome, with implications for nitrate‐polluted water remediation. [ABSTRACT FROM AUTHOR]

The influence of bacterial nutrition (by ethanol) on the appearance of hydrogen sulfide and colloidal sulfur in the filtrate of innovative U-shaped small-sized (point-of-use) submersible denitrifying biofilter describes in the course of its regular operation. The device intends to get drinking water from groundwater sources contaminated with nitrates, sulfates, and heavy metal ions. Colonies of denitrifying bacteria occupy an ecological niche inside the filter bed in an anoxic medium in the inlet elbow of the biofilter and reduce the concentration of nitrates below of hygienic limit at the optimal feed by ethanol. Hydrogen sulfide and colloidal sulfur produce the sulfate-reducing and sulfur bacteria. Sulfate-reducing bacteria act in an anaerobic environment in the bottom conjunction zone of the inlet and outlet elbows of the biofilter. These bacteria release hydrogen sulfide when ethanol adds to filtering water in excess compared to the dosage required for denitrification. Colonies of sulfur bacteria occupy an ecological niche in the output zone of the biofilter exit elbow and oxidise hydrogen sulfide to elemental sulfur. Sulfate reduction associated with nitrates removal can be helpful for additional water purification from admixtures of heavy and polyvalent metal ions. [ABSTRACT FROM AUTHOR]

Low carbon-to-nitrogen (C/N) ratios are the main characteristic of domestic wastewater. In this study, we evaluated the nitrate removal characteristics of Pseudomonas sp. XS-18 at low C/N ratios (4.0 and 6.0) and pH 11.0. We also analyzed the causes of the nitrate removal at low C/N ratios in this strain. At pH 11.0 and a C/N ratio of 4.0, the strain was effective in removing nitrate. Additionally, the total organic carbon content decreased over time at low C/N ratios, requiring more energy to complete vital activities. Furthermore, low C/N conditions resulted in less strain secretion compared to high C/N settings, and the polysaccharide content degraded more quickly than protein over time. To provide a carbon source for the nitrate reduction process, strains with low C/N ratio and high pH secreted more soluble microbial by-products. This strain is able to metabolize its own secreted extracellular polymeric substances as a carbon source to enhance nitrate removal. [ABSTRACT FROM AUTHOR]

Water quality parameters influence the abundance of pathogenic bacteria. The genera Aeromonas, Arcobacter, Klebsiella, and Mycobacterium are among the representative pathogenic bacteria identified in wastewater. However, information on the correlations between water quality and the abundance of these bacteria, as well as their reduction rate in existing wastewater treatment facilities (WTFs), is lacking. Hence, this study aimed to determine the abundance and reduction rates of these bacterial groups in WTFs. Sixty-eight samples (34 influent and 34 non-disinfected, treated, effluent samples) were collected from nine WTFs in Japan and Thailand. 16S rRNA gene amplicon sequencing analysis revealed the presence of Aeromonas, Arcobacter, and Mycobacterium in all influent wastewater and treated effluent samples. Quantitative real-time polymerase chain reaction (qPCR) was used to quantify the abundance of Aeromonas, Arcobacter, Klebsiella pneumoniae species complex (KpSC), and Mycobacterium. The geometric mean abundances of Aeromonas, Arcobacter, KpSC, and Mycobacterium in the influent wastewater were 1.2 × 104–2.4 × 105, 1.0 × 105–4.5 × 106, 3.6 × 102–4.3 × 104, and 6.9 × 103–5.5 × 104 cells mL−1, respectively, and their average log reduction values were 0.77–2.57, 1.00–3.06, 1.35–3.11, and −0.67–1.57, respectively. Spearman's rank correlation coefficients indicated significant positive or negative correlations between the abundances of the potentially pathogenic bacterial groups and Escherichia coli as well as water quality parameters, namely, chemical/biochemical oxygen demand, total nitrogen, nitrate-nitrogen, nitrite-nitrogen, ammonium-nitrogen, suspended solids, volatile suspended solids, and oxidation-reduction potential. This study provides valuable information on the development and appropriate management of WTFs to produce safe, hygienic water. [ABSTRACT FROM AUTHOR]

Bacterial communities are important components of reservoir ecosystems, participating in and determining the material–energy transformations within reservoirs. The intense material–energy transport during the flood season can cause perturbations to the stratified environment and material distribution within the reservoir, with the bacterial community being the most sensitive indicator of these changes. In this study, we analyzed sediments from four representative sampling sites before and after the flood season in a seasonally stratified reservoir and compared the diversity and composition of bacterial communities before and after the flood season using 16S rRNA high-throughput sequencing technology. The results showed that the bacterial community structure was different before and after flood season, and the bacterial abundance and α diversity were slightly higher before flood season than after flood season, and the relative abundance of bacteria was relatively low, and the dominant genera were not obvious. After flood season, the dominant genera were mainly Acinetobacter, Flavobacterium, Pseudomonas, Arthrobacter, and Massilia, all of which were aerobic denitrifying bacteria with strong denitrification ability. It is clear that the reservoir bacterial community structure changes significantly between flood seasons and plays a key role in later stages of aquatic ecology restoration. These results provide a new way of interpreting the dynamic changes in reservoir aquatic ecology. [ABSTRACT FROM AUTHOR]

The denitrification process is one of the important processes in the soil nitrogen (N) cycle, and is closely related to the loss of soil N fertilizer. Five treatments were included in this study: N0 (control, no N application); N90 (N application rate 90 kg ha−1); N150 (N application rate 150 kg ha−1); N210 (N application rate 210 kg ha−1); and N270 (N application rate 270 kg ha−1), to study the effect of different N application rates on the soil nirS-type denitrifying bacterial community structure, the influence of key enzyme activities during the denitrification process, and the main environmental factors affecting the variation of the denitrifying bacterial community in maize field soil under the mulched fertigation system in the semi-arid region of Northeast China. The results showed that increasing N fertilizer application significantly increased the contents of soil inorganic N and acid-hydrolyzable organic N, but significantly decreased pH. N fertilizer significantly increased nitrate reductase (NAR) activity and nitrite reductase (NIR) activity. Excessive application of N fertilizer significantly increased the nirS gene copy numbers, and, at the same time, significantly decreased the diversity of nirS-type soil denitrifying bacteria. Proteobacteria was the dominant denitrifying phylum in all treatments, and N application promoted the growth of Bradyrhizobium belonging to this phylum. The application of N fertilizer significantly changed the community structure of nirS denitrifying bacteria, and the NO3−-N content was the most important factor for this observation. Soil organic matter (SOM) and non-hydrolyzable N (NHN) indirectly affected the denitrifying bacterial community structure through NAR activity and NIR activity, while soil total N (TN) and nitrate N (NO3−-N) indirectly affected yield through denitrifying bacterial community structure. Although increasing N fertilizer was beneficial in increasing soil nutrients, the community structure of nirS-type denitrifying bacteria changed significantly. This is attributed to the increase in soil NO3−-N accumulation caused by a large amount of N application. The results of this research provide an important scientific basis for further research on the response mechanism of farmland soil denitrifying microorganisms to different N fertilizer managements under the mulched fertigation system in the semi-arid region of Northeast China. [ABSTRACT FROM AUTHOR]

• 30 mg/L of combined SMX and TMP increased TN removal (∼70%) and achieved SND. • Abundant genera were more affected by legacy of antibiotics than rare genera. • Rare taxa were keystone taxa in network based on the full-scale classification. • Shared hosts of ARGs and hub ARGs were observed under legacy of antibiotics stress. • Antibiotics legacy effect was more obvious at higher levels of antibiotic stress. The effect of combined antibiotics exposure on nitrogen removal, microbial community assembly and proliferation of antibiotics resistance genes (ARGs) is a hotspot in activated sludge system. However, it is unclear that how the historical antibiotic stress affects the subsequent responses of microbes and ARGs to combined antibiotics. In this study, the effects of combined sulfamethoxazole (SMX) and trimethoprim (TMP) pollution on activated sludge under legacy of SMX or TMP stress with different doses (0.005-30 mg/L) were investigated to clarify antibiotic legacy effects. Nitrification activity was inhibited under higher level of combined exposure but a high total nitrogen removal (∼70%) occurred. Based on the full-scale classification, the legacy effect of past antibiotic stress had a marked effect on community composition of conditionally abundant taxa (CAT) and conditionally rare or abundant taxa (CRAT). Rare taxa (RT) were the keystone taxa in the microbial network, and the responses of hub genera were also affected by the legacy of antibiotic stress. Nitrifying bacteria and genes were inhibited by the antibiotics and aerobic denitrifying bacteria (Pseudomonas, Thaurea and Hydrogenophaga) were enriched under legacy of high dose, as were the key denitrifying genes (napA, nirK and norB). Furthermore, the occurrences and co-selection relationship of 94 ARGs were affected by legacy effect. While, some shared hosts (eg., Citrobacter) and hub ARGs (eg., mdtD, mdtE and acrD) were identified. Overall, antibiotic legacy could affect responses of activated sludge to combined antibiotic and the legacy effect was stronger at higher exposure levels. [Display omitted] [ABSTRACT FROM AUTHOR]

This study evaluated the mechanical properties and self-healing performance of freshly casted and 19-month-aged bioconcrete samples with integrated sulfate-reducing bacteria (SRB) and nitrate-reducing bacteria (NRB) granules that were cultivated in an upflow anaerobic sludge blanket (UASB) reactor with synthetic wastewater. The 28-day compressive strength fulfilled the design requirement of 50 MPa. The apparent volume of permeable voids (AVPV) of fresh and aged bioconcrete met the limit of 13%. The self-healing ability was determined by exposing cracked bioconcrete to water media such as glucose, calcium acetate, tap water, and wastewater, which have shown calcite deposition in fresh and aged samples. The highest amount of calcite deposition was seen on fresh samples after glucose exposure (420 μm) and on aged bioconcrete after calcium acetate exposure (320 μm). Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS/XRD) results demonstrated that SRB/NRB granules survived mortar integration and deposition of calcite in both fresh and aged samples. The water permeability and acid resistance of bioconcrete samples were correlated to the amount of deposited calcite. [ABSTRACT FROM AUTHOR]

BACKGROUND: Gut microbiota have been implicated in atherosclerotic disease, but their relation with subclinical coronary atherosclerosis is unclear. This study aimed to identify associations between the gut microbiome and computed tomography-based measures of coronary atherosclerosis and to explore relevant clinical correlates. METHODS: We conducted a cross-sectional study of 8973 participants (50 to 65 years of age) without overt atherosclerotic disease from the population-based SCAPIS (Swedish Cardiopulmonary Bioimage Study). Coronary atherosclerosis was measured using coronary artery calcium score and coronary computed tomography angiography. Gut microbiota species abundance and functional potential were assessed with shotgun metagenomics sequencing of fecal samples, and associations with coronary atherosclerosis were evaluated with multivariable regression models adjusted for cardiovascular risk factors. Associated species were evaluated for association with inflammatory markers, metabolites, and corresponding species in saliva. RESULTS: The mean age of the study sample was 57.4 years, and 53.7% were female. Coronary artery calcification was detected in 40.3%, and 5.4% had at least 1 stenosis with >50% occlusion. Sixty-four species were associated with coronary artery calcium score independent of cardiovascular risk factors, with the strongest associations observed for Streptococcus anginosus and Streptococcus oralis subsp oralis (P<1×10-5). Associations were largely similar across coronary computed tomography angiography-based measurements. Out of the 64 species, 19 species, including streptococci and other species commonly found in the oral cavity, were associated with high-sensitivity C-reactive protein plasma concentrations, and 16 with neutrophil counts. Gut microbial species that are commonly found in the oral cavity were negatively associated with plasma indole propionate and positively associated with plasma secondary bile acids and imidazole propionate. Five species, including 3 streptococci, correlated with the same species in saliva and were associated with worse dental health in the Malmö Offspring Dental Study. Microbial functional potential of dissimilatory nitrate reduction, anaerobic fatty acid ß-oxidation, and amino acid degradation were associated with coronary artery calcium score. CONCLUSIONS: This study provides evidence of an association of a gut microbiota composition characterized by increased abundance of Streptococcus spp and other species commonly found in the oral cavity with coronary atherosclerosis and systemic inflammation markers. Further longitudinal and experimental studies are warranted to explore the potential implications of a bacterial component in atherogenesis. [ABSTRACT FROM AUTHOR]

Bacteria specialized in anaerobic ammonium oxidation (anammox) are widespread in many anoxic habitats and form an important functional guild in the global nitrogen cycle by consuming bio-available nitrogen for energy rather than biomass production. Due to their slow growth rates, cultivation-independent approaches have been used to decipher their diversity across environments. However, their full diversity has not been well recognized. Here, we report a new family of putative anammox bacteria, “Candidatus Subterrananammoxibiaceae,” existing in the globally distributed terrestrial and marine subsurface (groundwater and sediments of estuary, deep-sea, and hadal trenches). We recovered a high-quality metagenome-assembled genome of this family, tentatively named “Candidatus Subterrananammoxibius californiae,” from a California groundwater site. The “Ca. Subterrananammoxibius californiae” genome not only contains genes for all essential components of anammox metabolism (e.g., hydrazine synthase, hydrazine oxidoreductase, nitrite reductase, and nitrite oxidoreductase) but also has the capacity for urea hydrolysis. In an Arctic ridge sediment core where redox zonation is well resolved, “Ca. Subterrananammoxibiaceae” is confined within the nitrate-ammonium transition zone where the anammox rate maximum occurs, providing environmental proof of the anammox activity of this new family. Phylogenetic analysis of nitrite oxidoreductase suggests that a horizontal transfer facilitated the spreading of the nitrite oxidation capacity between anammox bacteria (in the Planctomycetota phylum) and nitrite-oxidizing bacteria from Nitrospirota and Nitrospinota. By recognizing this new anammox family, we propose that all lineages within the “Ca. Brocadiales” order have anammox capacity. IMPORTANCE Microorganisms called anammox bacteria are efficient in removing bioavailable nitrogen from many natural and human-made environments. They exist in almost every anoxic habitat where both ammonium and nitrate/nitrite are present. However, only a few anammox bacteria have been cultured in laboratory settings, and their full phylogenetic diversity has not been recognized. Here, we present a new bacterial family whose members are present across both the terrestrial and marine subsurface. By reconstructing a high-quality genome from the groundwater environment, we demonstrate that this family has all critical enzymes of anammox metabolism and, notably, also urea utilization. This bacterium family in marine sediments is also preferably present in the niche where the anammox process occurs. These findings suggest that this novel family, named “Candidatus Subterrananammoxibiaceae,” is an overlooked group of anammox bacteria, which should have impacts on nitrogen cycling in a range of environments. [ABSTRACT FROM AUTHOR]

Bioelectrochemical system is a novel method for controlling down nitrate pollution, yet the feasibility of using methane as the electron donors for denitrification in this system remains unknown. In this study, using the effluent from mother BESs as inocula, a denitrifying anaerobic methane oxidation bioelectrochemical system was successfully started up in 92 days. When operated with 50 mmol/L phosphate buffer solution at pH 7 and 30°C, the maximum methane consumption, nitrate, and total nitrogen removal load reached 0.23 ± 0.01 mmol/d, 551.0 ± 22.1 mg N/m3/d, and 64.0 ± 18.8 mg N/m3/d, respectively. Meanwhile, the peak voltage of 93 ± 4 mV, the anodic coulombic efficiency of 6.99 ± 0.20%, and the maximum power density of 219.86 mW/m3 were obtained. The metagenomics profiles revealed that the dominant denitrifying bacteria in the cathodic chamber reduced most nitrate to nitrite through denitrification and assimilatory reduction. In the anodic chamber, various archaea including methanotrophs and methanogens converted methane via reverse methanogenesis to form formate (or H2), acetate, and methyl compounds, which were than utilized by electroactive bacteria to generate electricity. Practitioner Points: A denitrifying anaerobic methane oxidation BES was successfully started up in 92 d.Simultaneous removal of methane and nitrate was achieved in the DAMO‐BES.Functional genes related to AMO and denitrification were detected in the DAMO‐BES.Methylocystis can mediate AMO in the anode and denitrification in the cathode. [ABSTRACT FROM AUTHOR]

The copper-containing nitrite reductase from Neisseria gonorrhoeae has been shown to play a critical role in the infection mechanism of this microorganism by producing NO and abolishing epithelial exfoliation. This enzyme is a trimer with a type 1 copper center per subunit and a type 2 copper center in the subunits interface, with the latter being the catalytic site. The two centers were characterized for the first time by EPR and CD spectroscopy, showing that the type 1 copper center has a high rhombicity due to its lower symmetry and more tetragonal structure, while the type 2 copper center has the usual properties, but with a smaller hyperfine coupling constant (A// = 10.5 mT). The thermostability of the enzyme was analyzed by differential scanning calorimetry, which shows a single endothermic transition in the thermogram, with a maximum at 94 °C, while the CD spectra in the visible region indicate the presence of the type 1 copper center up to 80 °C. The reoxidation of the N. gonorrhoeae copper-containing nitrite reductase in the presence of nitrite were analyzed by visible spectroscopy and showed a pH dependence, being higher at pH 5.5–6.0. The high thermostability of this enzyme may be important to maintaining a high activity in the extracellular space and to making it less susceptible to denaturation and proteolysis, contributing to the proliferation of N. gonorrhoeae. [ABSTRACT FROM AUTHOR]

Reservoirs are important sites for nitrogen processing, especially those located in agricultural and urban watersheds. Nitrogen inputs promote N2O production and emission, but the microbial pathways controlling N2O have been seldom studied in reservoir water columns. We determined N2O concentration in the water column of 12 reservoirs during the summer stratification and winter mixing. We explored the potential microbial sources and sinks of N2O by quantifying key genes involved in ammonia oxidation (bacterial and archaeal amoA) and denitrification (nirS and nosZ). Dissolved N2O varied up to three orders of magnitude (4.7–2441.2 nmol L−1) across systems, from undersaturated to supersaturated values (37%–24,174%) depending on reservoirs and depths. N2O concentration depended on nitrogen and oxygen availabilities, with the lowest and highest N2O values at suboxic conditions. Ammonia‐oxidizing archaea dominated over ammonia‐oxidizing bacteria but were not related to the dissolved N2O. In contrast, the abundance of the nirS gene was significantly related to N2O concentration, and three orders of magnitude higher than amoA abundance. Denitrifying bacteria appeared consistently in the water column of all reservoirs. The nirS and nosZ genes appeared in oxic and suboxic waters, but they were more abundant in suboxic waters. The nitrate concentration, and nirS and nosZ relative abundances explained the dissolved N2O. Besides, nirS abundance was related positively with total phosphorus and cumulative chlorophyll a, a proxy for fresh organic matter. Therefore, P inputs, not just N inputs, promoted N2O production by denitrification in the water column of reservoirs. [ABSTRACT FROM AUTHOR]

Denitrifying bacteria play critical roles in enhancing biological biofilm denitrification for nitrogen removal in industrial and municipal wastewater treatment and groundwater remediation. Evidence intensively confirms that exogenous quorum sensing (QS) bacteria prompt biofilm formation and denitrification. Yet, exogenous bacteria forfeiting during bioaugmentation may occur despite of its priority effect and improved community function, because of open, intricate traits in wastewater treatment system. Critical topics include regulating signal-based microecological structure, effectively assembling 3D biofilm, and regulating carbon and nitrogen metabolization of denitrifiers to reduce CO2 and N2O emissions. This review demonstrates classifications of denitrifiers and the vital role of QS in regulating biofilm denitrification. Furthermore, the ecological principles of microbial community construction with the addition of exogenous denitrifiers are summarized. Moreover, the effects of signaling molecules on carbon and nitrogen transcription and metabolization are discussed. In conclusion, technologies based on quorum sensing for enhanced denitrification have high application potential and challenges. Herein, we provide a guideline for enhancing nitrogen removal by exogenous quorum-sensing bacteria and synthetic biofilms design during upgrading of municipal wastewater treatment plants. [ABSTRACT FROM AUTHOR]

Microbial fuel cell (MFC) technology with decarbonization and denitrification is considered to be advantageous in treating wastewater with a low carbon-to-nitrogen ratio. In this study, MFC was treated with different concentrations of nitrate-nitrogen. The MFC technology revealed significant treatment advantages when compared to both abiotic electrode treatment and microbial treatment only. The best treatment effect was recorded when the MFC's nitrate-nitrogen ( N O 3 − − N ) concentration was 414 mg/L. The running of the MFC system showed that it produced a stable output voltage of up to 0.17 V within 160 h. It showed a power density of up to 40.18 mW/m2, 1.58 times M1 (138 mg/L, 25.49 mW/m2), and 4.48 times non-biological electrode. The removal rate of N O 3 − − N was 97.48%, but the lack of anode electron supply resulted in the incomplete reduction of nitrate-nitrogen and accumulation of nitritenitrogen. Nitrate-nitrogen concentration in the study had no significant impact on microbial population diversity. However, the relative abundance of Proteobacteria increased from 47.3% to 65.4% when N O 3 − − N concentration increased from 138 to 414 mg/L. Burkholderiales, Hydrogenophilales, and Rhodocyclales were the main denitrifying bacteria. These results demonstrate promise in supporting the development of microbial cathode denitrification. [ABSTRACT FROM AUTHOR]

The regulation of microbial subpopulations in wastewater treatment plants (WWTPs) with desired functions can guarantee nutrient removal. In nature, "good fences make good neighbors," which can be applied to engineering microbial consortia. Herein, a membrane-based segregator (MBSR) was proposed, where porous membranes not only promote the diffusion of metabolic products but also isolate incompatible microbes. The MBSR was integrated with an anoxic/aerobic membrane bioreactor (i.e., an experimental MBR). The long-term operation showed that the experimental MBR exhibited higher nitrogen removal (10.45 ± 2.73 mg/L total nitrogen) than the control MBR (21.68 ± 4.23 mg/L) in the effluent. The MBSR resulted in much lower oxygen reduction potential in the anoxic tank of the experimental MBR (-82.00 mV) compared to that of the control MBR (83.25 mV). The lower oxygen reduction potential can inevitably aid in the occurrence of denitrification. The 16S rRNA sequencing showed that the MBSR significantly enriched acidogenic consortia, which yielded considerable volatile fatty acids by fermenting the added carbon sources and allowed efficient transfer of these small molecules to the denitrifying community. Moreover, the sludge communities of the experimental MBR harbored a higher abundance of denitrifying bacteria than those of the control MBR. Metagenomic analysis further corroborated these sequencing results. The spatially structured microbial communities in the experimental MBR system demonstrate the practicability of the MBSR, achieving nitrogen removal efficiency superior to that of mixed populations. Our study provides an engineering method for modulating the assembly and metabolic division of labor of subpopulations in WWTPs. [ABSTRACT FROM AUTHOR]

Microbial Fuel Cell (MFC) is an environmentally friendly and sustainable technology where microbial degradation on organic substrates generates electricity, with potential application to wastewater treatment. This study mainly focused on investigating the effects of wastewater source on efficient electricity generation using a bio-cathode. Carbon cloth (2 × 4 cm2) were used as anode and cathode electrodes with 0.33O external resistor. Anode medium was leachate (setup 01) and rice wash water (setup 02) and cathode medium was Chroococcus sp. culture. Control setup was maintained by adding distilled water in cathode. Landfill leachate and rice wash water were used as the wastewater sources, all other conditions were the same in both setups. Highest electricity generation and wastewater treatment were recorded in setup 02 with rice wash water. The maximum voltage was 1,111 mV with current 3,366.67 mA and 467.55 mW m-2 power density. The wastewater treatment efficiencies reported as reductions in COD, Nitrate, Nitrite and Orthophosphate were 61.94%, 61.01%, 55.14%, and 26.01% in setup 02. These study outcomes disclose that dual chamber MFC with rice wash water as the wastewater source has potential for simultaneous power generation and wastewater treatment. [ABSTRACT FROM AUTHOR]

Metabolic syndrome is considered to be a cluster of disorders that directly contribute to the development of cardiovascular disease and are characterized by chronic systemic inflammation. Numerous epidemiological data indicate that an adverse intrauterine environment, caused by the peculiarities of the nutritional status or placental insufficiency in a woman with metabolic syndrome, can "program" the susceptibility of the fetus to further development of cardiovascular and metabolic diseases, has an impact on cognitive and behavioral development. Nitric oxide (NO) plays a critical role in the pathogenesis of components of the metabolic syndrome. Children born prematurely have a high incidence of brain damage, which can lead to motor, cognitive, behavioral, social and sensory disorders. The purpose the research was the study of the effect of the eNOS gene polymorphism and indicators of nitric oxide metabolism on the neonatal consequences in prematurely born children from mothers with metabolic syndrome. Material and methods. A study was conducted in which 100 premature infants were included. Two groups were formed: the main group (n=34), which included preterm infants (birth weight 2145.29±148.19 g and gestational age 33.18±0.55 weeks) of mothers with metabolic syndrome, and the comparison group (n=66), which included preterm infants (birth weight 2295.99±101.45 and gestational age 34.03±0.45 weeks) of mothers without metabolic syndrome. The children underwent a genetic study - determination of the polymorphism of the eNOS gene, as well as the level of nitrites, nitrates and nitrosothiols in the urine. By decision of the bioethics commission No. 217 dated 12.06.2023, the materials of the scientific work comply with the Rules of Humane Treatment of Patients. Traditional methods of parametric and nonparametric statistics were used; nonparametric methods were used to analyze qualitative characteristics expressed mainly in percentages. The methods of parametric statistics were used to check the normality of the distribution of quantitative characteristics using the Kolmogorov-Smirnov criterion. Statistical processing of the obtained results was carried out using the package of application programs EXCEL-2003® and STATA version 11 for Windows (StataCorp, Texas, USA). The work was carried out as part of the scientific and experimental work of the Department of Pediatrics #1 with Neonatology of the Poltava State Medical University "To develop clinical and laboratory criteria, methods of predicting and preventing metabolic disoders in young children (state registration number 0120U102856). Results. The most common diseases in the infants of the studied groups were the consequences of intrauterine hypoxia (44.1%) and respiratory failure requiring artificial lung ventilation (50.0%), although no significant differences were found in the prevalence of these conditions. We identified the presence of significant associations between the consequences of intrauterine hypoxia and the levels of nitrates (OR 1.19; 95% CI 1.01-1.40; p=0.042), nitrosothiols (OR 1.19; 95% CI 0.99-1.42; p=0.050) and the polymorphic genotype 4aa/ab of the eNOS gene (OR 0.28; 95% CI 0.12-0.67; p=0.004). Analysis of systemic hemodynamics revealed no significant differences in baseline values between preterm infants with and without intrauterine hypoxia, but we did observe an association with urine output on day 3 of life. To finally clarify the complex influence of indicators of nitrate metabolism on the development of intrauterine hypoxia and to predict the development of consequences of this condition in premature infants, the following indicators are included in the regression prognostic model: the level of nitrates, nitrites, 4aa/4ab genotype and urine output on the third day of life. As the research results show, there is a direct reliable relationship with nitrates and an inverse relationship with nitrites, 4aa/4ab genotype and urine output. This prediction model has high operating characteristics - the area under the ROC curve is 0.8168. Some mechanisms of the influence of maternal metabolic syndrome on the development of relevant disorders in newborns are known, including disorders of nitric oxide synthesis, endothelial dysfunction, and oxidative stress. In our study, the consequences of intrauterine hypoxia were reliably associated with an increase in the concentration of urinary nitrates and a decrease in nitrites, as well as the absence of the 4aa/ab genotype, which is associated with reduced release of nitric oxide. There is evidence that nitric oxide can have both protective and deleterious effects, depending on factors such as nitric oxide synthase isoform and duration of exposure to hypoxia. Conclusions. In preterm infants born to mothers with metabolic syndrome, elevated urinary nitrate levels and the absence of the eNOS 4aa/ab genotype increase the likelihood of suffering the consequences of intrauterine hypoxia. [ABSTRACT FROM AUTHOR]

In this study, we sought to investigate the impact of urbanization, the presence of concrete river bottoms, and nutrient pollution on microbial communities along the L.A. River. Six molecular markers were evaluated for the identification of bacteria, plants, fungi, fish, and invertebrates in 90 samples. PCA (principal components analysis) was used along with PAM (partitioning around medoids) clustering to reveal community structure, and an NB (negative binomial) model in DESeq2 was used for differential abundance analysis. PCA and factor analysis exposed the main axes of variation but were sensitive to outliers. The differential abundance of Proteobacteria was associated with soft-bottom sites, and there was an apparent balance in the abundance of bacteria responsible for nitrogen cycling. Nitrogen cycling was explained via ammonia-oxidizing archaea; the complete ammonia oxidizers, Nitrospira sp.; nitrate-reducing bacteria, Marmoricola sp.; and nitrogen-fixing bacteria Devosia sp., which were differentially abundant at soft-bottom sites (p adj < 0.002). In contrast, the differential abundance of several cyanobacteria and other anoxygenic phototrophs was associated with the impervious sites, which suggested the accumulation of excess nitrogen. The soft-bottom sites tended to be represented by a differential abundance of aerobes, whereas the concrete-associated species tended to be alkaliphilic, saliniphilic, calciphilic, sulfate dependent, and anaerobic. In the Glendale Narrows, downstream from multiple water reclamation plants, there was a differential abundance of cyanobacteria and algae; however, indicator species for low nutrient environments and ammonia-abundance were also present. There was a differential abundance of ascomycetes associated with Arroyo Seco and a differential abundance of Scenedesmaceae green algae and cyanobacteria in Maywood, as seen in the analysis that compared suburban with urban river communities. The proportion of Ascomycota to Basidiomycota within the L.A. River differed from the expected proportion based on published worldwide freshwater and river 18S data; the shift in community structure was most likely associated with the extremes of urbanization. This study indicates that extreme urbanization can result in the overrepresentation of cyanobacterial species that could cause reductions in water quality and safety. [ABSTRACT FROM AUTHOR]

To analyze the effects of soil acidity on tea quality and the ability of soil nitrogen transformation, the tea leaves and tea tree rhizosphere soils were collected from 26-tea plantations and determined their contents of theanine and amino acids in tea leaves, the number of soil nitrogen transforming microorganisms and soil biochemical intensity. The results showed that the content of theanine and amino acid in tea leaves, the number of aerobic nitrogen-fixing bacteria and ammonifying bacteria in the soil and the nitrogen fixation intensity and ammonification intensity of the soil increased with the increase of pH value of tea tree rhizosphere soil. However, the number of soil nitrifying bacteria and denitrifying bacteria and soil nitrification intensity and denitrification intensity showed a downward trend. The results of principal component analysis showed that the contribution rate of principal component 1 and principal component 2 was 84.97 % and 7.57 %, respectively. In the soil with different acidity, the main contribution to differentiate the amino acid and theanine content in tea leaves came from the ability of soil for nitrogen fixation and ammonification as well as the ability of soil nitrification and denitrification. The results of correlation analysis showed that soil pH value was significantly positively correlated with theanine, amino acid, aerobic nitrogen-fixing bacteria, ammonifying bacteria, nitrogen fixation intensity and ammoniating intensity, while significantly negatively correlated with nitrifying bacteria, denitrifying bacteria, nitrification intensity and denitrification intensity. The intensification of soil acidity decreased the nitrogen fixation and ammonification activities and boosted nitrification and denitrification activities and decreased the quality of tea leaves. [ABSTRACT FROM AUTHOR]

The objective is to explore the denitrification and phosphorus removal conditions and performance of a efficient denitrifying phosphorus-accumulating bacterium, and its treatment effect on simulated wastewater. Denitrifying phosphorus-accumulating strain D4 was isolated by pure culture technology. Preliminary identification of the strain was completed based on 16S rRNA gene sequence analysis and physiological and biochemical characteristics, and the denitrification and dephosphorization conditions were optimized by single factor and response surface method, so as to achieve efficient biological denitrification and dephosphorization of mimic food wastewater. As results， denitrifying phosphorus-accumulating bacterium D4 was Gordonia sp.. The optimal conditions for nitrogen and phosphorus removal were sodium acetate (3.32 g/L) as carbon source, 5% inoculum, initial phosphorus content of 18.61 mg/L, 31.3℃, and pH 7.9. Under these conditions, the removed amounts of total phosphorus, nitrate nitrogen and ammonia nitrogen by strain D4 were 14.18, 39.67 and 69.71 mg/L, respectively; and the corresponding removal rates were 84.50%, 97.67% and 96.22%. Results of treatment to different simulated wastewater showed that strain D4 had the best nitrogen and phosphorus removal effects in soybean product wastewater, with the removed amount of nitrogen and phosphorus being 101.58 mg/L and 10.40 mg/L, respectively. In conclusion, strain D4 has promising denitrification and phosphorus-accumulating ability and is a good strain resource for biological denitrification and phosphorus removal of food processing wastewater with high nitrogen and phosphorus such as soybean product wastewater. [ABSTRACT FROM AUTHOR]

Nitrite oxidizing bacteria (NOB) is easy to accumulate in the mainstream anammox process, leading to the decrease of anammox bacterial abundance and deterioration of nitrogen removal. In this study, anammox bacteria was gradually enriched by increasing nitrite production rate under intermittent aeration despite high NOB abundance. With the DO increased from 0.4 to 0.6 mg/L, Nitrosomonas increased from 0.14% to 0.22%, providing more nitrite for anammox bacteria and promoting its enrichment (grew by 77.4%). Adding extra nitrite of 7.14 mg N/(L·h) during the aeration phase to reactor could further increase anammox bacterial abundance by 117.6%, which was higher than the control reactor (40.2%). In contrast, NOB abundance decreased from 1.4 × 1010 to 1.2 × 1010 copies/L. The results suggested that anammox bacteria had a competitive advantage for nitrite over NOB with increasing nitrite production rate. In addition, Thauera and Dechloromonas, which were responsible for reducing nitrate to nitrite, provided additional substrates for anammox bacteria. Overall, this research provides a new idea for mainstream anammox applications. Practitioner Points: Inhibiting NOB might be no longer necessary and difficult for mainstream anammox.Anammox bacteria competed for more nitrite with NOB when nitrite production rate increased.Increasing DO from 0.4 to 0.6 mg/L facilitated anammox bacterial growth and nitrogen removal. [ABSTRACT FROM AUTHOR]

Background: Recently, it has been found that nitrogen (N) deposition strongly affects the coverage of biocrusts. However, we know little about the response of exopolysaccharides (EPSs), the key cementing material in the formation and stability of biocrusts, to N deposition. Method: Three N-sources including nitrate, ammonia and urea were added to biocrusts at three rates (2 mg/g, 4 mg/g, 8 mg/g) to evaluate the effect of N additions on the growth of biocrusts and the abundance of EPS. Results: Our results showed 2 mg/g of nitrate–N had no obvious effect on the cyanobacterial biomass, while 4 and 8 mg/g of nitrate–N inhibited the growth of Microcoleus vaginatus, the dominant cyanobacterium in biocrusts, but promoted other cyanobacteria growth. Ammonia-N and urea-N strongly decreased the cyanobacterial biomass, indicated by chlorophyll-a and 16 s rRNA gene copy-numbers. On the whole, N additions had a positive impact on the α-biodiversity of biocrusts. However, Ammonia-N and urea-N shifted the bacterial communities from more Cyanobacteria to more Proteobacteria and Actinobacteria. Notably, lesser-N (2 mg/g) promoted the excretion of EPSs, while greater-N (8 mg/g) had the opposite effect, and the total proportion of rhamnose and fucose in EPSs decreased in all treatment groups. Conclusion: N additions (except 2 mg/g of nitrate–N) reduced cyanobacterial biomass and affected the bacterial communities in biocrusts, which would obstruct the development and succession of biocrusts. Meanwhile, the simultaneous reductions of the EPSs contents and proportion of rhamnose and fucose in EPSs may further reduce stability and persistence of cyanobacterial biocrusts, after N additions. [ABSTRACT FROM AUTHOR]