Characteristic and mechanism of biological nitrogen and phosphorus removal facilitated by biogenic manganese oxides (BioMnOx) at various concentrations of Mn(II).

Biogenic manganese oxides (BioMnOx) have attracted considerable attention as active oxidants, adsorbents, and catalysts. However, characteristics and mechanisms of nitrification-denitrification in biological redox reactions mediated by different concentrations of BioMnOx are still unclear. Fate of nutrients (e.g., NH4+-N, TP, NO3--N) and COD were investigated through different concentrations of BioMnOx produced by Mn(II) in the moving bed biofilm reactor (MBBR). 34% and 89.2%, 37.8% and 89.8%, 57.3% and 88.9%, and 62.1% and 90.4% of TN and COD by MBBR were synchronously removed in four phases, respectively. The result suggested that Mn(II) significantly improved the performance of simultaneous nitrification and denitrification (SND) and TP removal based on manganese (Mn) redox cycling. Characteristics of glutathione peroxidase (GSH-Px), reactive oxygen species (ROS), and electron transfer system activity (ETSA) were discussed, demonstrating that ROS accumulation reduced the ETSA and GSH-Px activities when Mn(II) concentration increased. Extracellular polymeric substance (EPS) function and metabolic pathway of Mn(II) were explored. Furthermore, effect of cellular components on denitrification was evaluated including BioMnOx performances, indicating that Mn(II) promoted the non-enzymatic action of cell fragments. Finally, mechanism of nitrification and denitrification, denitrifying phosphorus and Mn removal was further elucidated through X-ray photoelectron spectroscopy (XPS), high throughput sequencing, and fourier transform infrared reflection (FTIR). This results can bringing new vision for controlling nutrient pollution in redox process of Mn(II).

New insights into nitrogen removal by divalent iron-enhanced moving bed biofilm reactor: Performance, interfacial interaction and co-occurrence network.

A divalent iron-mediated moving bed biofilm reactor with intermittent aeration was developed to enhance the nitrogen removal at low carbon-to-nitrogen ratios. The study demonstrated thatammonia removal increased from 51 ± 4 % to 79 ± 4 % and nitrate removal increased from 72 ± 5 % to 98 ± 4 % in phases I-IV, and 2-5 mg·L-1 of divalent iron significantly increased the anoxic denitrification process. Divalent iron stimulated the secretion of extracellular polymeric substances, which facilitated the formation of cross-linked network between microbial cells. Furthermore, the cycle between divalent and trivalent iron decreased the energy barrier between the biofilm and the pollutant. The microbial community further revealed that Proteobacteria (relative abundance: 40-48 %) andBacteroidota(relative abundance: 31-37 %) were the dominant phyla, supporting the synchronous nitrification and denitrification processes as well as the lower accumulation of nitrite. In conclusion, iron redox cycling significantly enhanced the nitrogen removal. This study proposes a viable strategy for the efficient treatment of nutrient wastewater.

Revealing the biological significance of multiple metabolic pathways of chloramphenicol by Sphingobium sp. WTD-1.

Chloramphenicol (CAP) is an antibiotic that commonly pollutes the environment, and microorganisms primarily drive its degradation and transformation. Although several pathways for CAP degradation have been documented in different bacteria, multiple metabolic pathways in the same strain and their potential biological significance have not been revealed. In this study, Sphingobium WTD-1, which was isolated from activated sludge, can completely degrade 100 mg/L CAP within 60 h as the sole energy source. UPLC-HRMS and HPLC analyses showed that three different pathways, including acetylation, hydroxyl oxidation, and oxidation (C1-C2 bond cleavage), are responsible for the metabolism of CAP. Importantly, acetylation and C3 hydroxyl oxidation reduced the cytotoxicity of the substrate to strain WTD-1, and the C1-C2 bond fracture of CAP generated the metabolite p-nitrobenzoic acid (PNBA) to provide energy for its growth. This indicated that the synergistic action of three metabolic pathways caused WTD-1 to be adaptable and able to degrade high concentrations of CAP in the environment. This study deepens our understanding of the microbial degradation pathway of CAP and highlights the biological significance of the synergistic metabolism of antibiotic pollutants by multiple pathways in the same strain.

Efficacy of epigallocatechin gallate (EGCG) and its underlying mechanism in preventing bisphenol-A-induced metabolic disorders in mice.

To investigate the efficacy of epigallocatechin gallate (EGCG) and its underlying mechanism in preventing bisphenol-A-induced metabolic disorders, in this study, a mice model of metabolic disorders induced by BPA was developed to investigate the efficacy and mechanism of EGCG using microbiomes and metabolomics. The results showed that EGCG reduced body weight, liver weight ratio, and triglyceride and total cholesterol levels in mice by decreasing the mRNA expression of genes related to fatty acid synthesis (Elov16) and cholesterol synthesis (CYP4A14) and increasing the mRNA expression of genes related to fatty acid oxidation (Lss) and cholesterol metabolism (Cyp7a1). In addition, EGCG normalized BPA-induced intestinal microbial dysbiosis. Metabolic pathway analysis showed that low-dose EGCG was more effective than high-dose EGCG at affecting the biosynthesis of L-cysteine, glycerophosphorylcholine, and palmitoleic acid. These results provide specific data and a theoretical basis for the risk assessment of BPA and the utilization of EGCG.

Impact of Flooding-Drainage Alternation on Fe Uptake and Transport in Rice: Novel Insights from Iron Isotopes.

Iron (Fe) isotopes were utilized to provide insights into the temporal changes underlying Fe uptake and translocation during rice growth (tillering, jointing, flowering, and maturity stages) in soil-rice systems under typical flooding-drainage alternation. Fe isotopic composition (δ56Fe values) of the soil solution generally decreased at vegetative stages in flooding regimes but increased during grain-filling. Fe plaques were the prevalent source of Fe uptake, as indicated by the concurrent increase in the δ56Fe values of Fe plaques and rice plants during rice growth. The increasing fractionation magnitude from stem/nodes I to flag leaves can be attributed to the preferred phloem transport of light isotopes toward grains, particularly during grain-filling. This study demonstrates that rice plants take up heavy Fe isotopes from Fe plaque and soil solution via strategy II during flooding and the subsequent drainage period, respectively, thereby providing valuable insights into improving the nutritional quality during rice production.

Insights into nitrate-reducing Fe(II) oxidation by Diaphorobacter caeni LI3T through kinetic, nitrogen isotope fractionation, and genome analyses.

Nitrate (NO3-)-reducing Fe(II) oxidation (NRFO) is prevalent in anoxic environments. However, it is uncertain in which step(s) the biological Fe(II) oxidation is coupled with denitrification during NRFO. In this study, a heterotrophic NRFO bacterium, Diaphorobacter caeni LI3T, was isolated from paddy soil and used to investigate the transformation of Fe(II) and nitrogen as well as nitrogen isotopic fractionation (δ15N-N2O) during NRFO. Fe(II) oxidation was observed in the Cell+NO3- +Fe(II), Cell+NO2- + Fe(II), and NO2- + Fe(II) treatments, resulting in precipitation of amorphous Fe(III) minerals and lepidocrocite on the surface and in the periplasm of cells. The presence of Fe(II) slightly accelerated microbial NO3- reduction in the Cell+NO3- + Fe(II) treatment relative to the Cell+NO3- treatment, but slowed down the NO2- reduction in the Cell+NO2- + Fe(II) treatment relative to the Cell+NO2- treatment likely due to cell encrustation that blocking microbial NO2- reduction in the periplasm. The δ15N-N2O results in the Cell+NO3- + Fe(II) treatment were close to those in the Cell+NO3- and Cell+NO2- treatments, indicating that the accumulative N2O is primarily of biological origin during NRFO. The genome analysis found a complete set of denitrification and oxidative phosphorylation genes in strain LI3T, the metabolic pathways of which were closely related with cyc2 and cytc as indicated by protein-protein interactions network analysis. It is proposed that Fe(II) oxidation is catalyzed by the outer membrane protein Cyc2, with the resulting electrons being transferred to the nitrite reductase NirS via CytC in the periplasm, and the CytC can also accept electrons from the oxidative phosphorylation in the cytoplasmic membrane. Overall, our findings provide new insights into the potential pathways of biological Fe(II) oxidation coupled with nitrate reduction in heterotrophic NRFO bacteria.

Chicken feedlot revisited: Co-dispersal of antibiotic and metal resistome under banning in-feed veterinary antibiotics.

Intensive livestock farming has been implicated as a notorious hotspot for antibiotic resistance genes (ARGs) due to the excessive or inappropriate use of in-feed antibiotics over the past few decades. Since China implemented a ban on the use of antibiotics in animal feed since 2020, the dissemination of ARGs in the vicinity of feedlots has remained unclear. This study presents a case study that aims to investigate the dispersal of antibiotics and ARGs from a chicken feedlot (established in 2020) to the adjacent aquatic and soil environments. Comparing the sample collected from upstream area, the water and sediment samples from midstream and downstream areas showed an increase in total antibiotic residues and metal content (Cu and Zn) by 4.2-5.3 fold and 1.3-22.6 fold, respectively. The downstream water samples exhibited a 2.49-2.93-fold increase in the abundance of ARGs and a 1.48-1.75-fold increase in the abundance of metal resistance genes (MRGs). The results of Pearson correlation and metagenome-assembled genome revealed a tendency for the co-occurrence of ARGs and MRGs. The dissemination of ARGs and MRGs is primarily driven by tetracycline, tylosin, Cu, and, Mn, with mobile genetic elements playing a more significant role than bacterial communities. These findings shed light on the overlooked co-dispersal pattern of ARGs and MRGs in the environment surrounding feedlots, particularly in the context of banning in-feed veterinary antibiotics.

Characteristics and catalytic mechanism of a novel multifunctional oxidase, CpmO, for chloramphenicols degradation from Sphingobium sp. WTD-1.

Chloramphenicols (CAPs) are ubiquitous emerging pollutants that threaten ecological environments and human health. Microbial and enzyme-based biodegradation strategies offer a cost-effective environmentally friendly approach for CAPs removal from contaminated sites. Here, CpmO, a novel multifunctional oxidase for CAP degradation was identified from the CAP-degrading strain Sphingobium sp. WTD-1. This enzyme was found to be responsible for both the oxidation of the C3-hydroxyl and oxidative cleavage of the C1-C2 bond of CAP, and the oxidative cleavage pathway of CAP was dominant. The catalytic efficiency of CpmO for CAP was 41.6 times that for thiamphenicol (TAP) under the optimal conditions (40 °C, pH 6.0). CpmO was identified as a member of the glucose-methanol-choline oxidoreductase family. Molecular docking and site-directed mutagenesis analysis indicated that CAP was connected to the key amino acid residues E231/E395, K277, and I273/A276 in CpmO through hydrogen bonding, nonclassical hydrogen bonding, and π-π stacking forces, respectively. The catalytic activities of the A276W, K277P, and E231S mutants were found to be 1.1 times, 6.4 times, and 13.2 times higher than that of the wild type, respectively. These findings provide genetic resources and theoretical guidance for future application in biotechnological and metabolic engineering efforts for the remediation of CAPs-contaminated environments.

Fe(II) Oxidation Shaped Functional Genes and Bacteria Involved in Denitrification and Dissimilatory Nitrate Reduction to Ammonium from Different Paddy Soils.

Microbial nitrate reduction can drive Fe(II) oxidation in anoxic environments, affecting the nitrous oxide emission and ammonium availability. The nitrate-reducing Fe(II) oxidation usually causes severe cell encrustation via chemodenitrification and potentially inhibits bacterial activity due to the blocking effect of secondary minerals. However, it remains unclear how Fe(II) oxidation and subsequent cell encrustation affect the functional genes and bacteria for denitrification and dissimilatory nitrate reduction to ammonium (DNRA). Here, bacteria were enriched from different paddy soils with and without Fe(II) under nitrate-reducing conditions. Fe(II) addition decelerated nitrate reduction and increased NO2- accumulation, due to the rapid Fe(II) oxidation and cell encrustation in the periplasm and on the cell surface. The N2O accumulation was lower in the treatment with Fe(II) and nitrate than that in the treatment with nitrate only, although the proportions of N2O and NH4+ to the reduced NO3- were low (3.25% ∼ 6.51%) at the end of incubation regardless of Fe(II) addition. The dominant bacteria varied from soils under nitrate-reducing conditions, while Fe(II) addition shaped a similar microbial community, including Dechloromonas, Azospira, and Pseudomonas. Fe(II) addition increased the relative abundance of napAB, nirS, norBC, nosZ, and nirBD genes but decreased that of narG and nrfA, suggesting that Fe(II) oxidation favored denitrification in the periplasm and NO2--to-NH4+ reduction in the cytoplasm. Dechloromonas dominated the NO2--to-N2O reduction, while Thauera mediated the periplasmic nitrate reduction and cytoplasmic NO2--to-NH4+ during Fe(II) oxidation. However, Thauera showed much lower abundance than the dominant genera, resulting in slow nitrate reduction and limited NH4+ production. These findings provide new insights into the response of denitrification and DNRA bacteria to Fe(II) oxidation and cell encrustation in anoxic environments.

Effect of antibiotics on the performance of moving bed biofilm reactor for simultaneous removal of nitrogen, phosphorus and copper(II) from aquaculture wastewater.

Co-existence of NO3--N, antibiotics, phosphorus (P), and Cu2+ in aquaculture wastewater has been frequently detected, but simultaneous removal and relationship between enzyme and pollutants removal are far from satisfactory. In this study, simultaneous removal of NO3--N, P, antibiotics, and Cu2+ by moving bed biofilm reactor (MBBR) was established. About 95.51 ± 3.40% of NO3--N, 61.24 ± 3.51% of COD, 18.74 ± 1.05% of TP, 88% of Cu2+ were removed synchronously in stage I, and antibiotics removal in stages I-IV was 73.00 ± 1.32%, 79.53 ± 0.88%, 51.07 ± 3.99%, and 33.59 ± 2.73% for tetracycline (TEC), oxytetracycline (OTC), chlortetracycline hydrochloride (CTC), sulfamethoxazole (SMX), respectively. The removal kinetics and toxicity of MBBR effluent were examined, indicating that the first order kinetic model could better reflect the removal of NO3--N, TN, and antibiotics. Co-existence of multiple antibiotics and Cu2+ was the most toxicity to E. coli growth. Key enzyme activity, reactive oxygen species (ROS) level, and its relationship with TN removal were investigated. The results showed that enzymes activities were significantly different under the co-existence of antibiotics and Cu2+. Meanwhile, different components of biofilm were extracted and separated, and enzymatic and non-enzymatic effects of biofilm were evaluated. The results showed that 70.00%- 94.73% of Cu2+ was removed by extracellular enzyme in stages I-V, and Cu2+ removal was mainly due to the action of extracellular enzyme. Additionally, microbial community of biofilm was assessed, showing that Proteobacteria, Bacteroidetes, and Gemmatimonadetes played an important role in the removal of NO3--N, Cu2+, and antibiotics at the phylum level. Finally, chemical bonds of attached and detached biofilm were characterized by X-ray photoelectron spectroscopy (XPS), and effect of nitrogen (N) and P was proposed under the co-existence of antibiotics and Cu2+. This study provides a theoretical basis for further exploring the bioremediation of NO3--N, Cu2+, and antibiotics in aquaculture wastewater.

A predictive model for preterm infants with bronchopulmonary dysplasia based on ferroptosis-related lncRNAs.

BACKGROUND: Bronchopulmonary dysplasia (BPD) is the most challenging chronic lung disease for prematurity, with difficulties in early identification. Given lncRNA emerging as a novel biomarker and the regulator of ferroptosis, this study aims to develop a BPD predictive model based on ferroptosis-related lncRNAs (FRLs). METHODS: Using a rat model, we firstly explored mRNA levels of ferroptosis-related genes and ferrous iron accumulation in BPD rat lungs. Subsequently, a microarray dataset of umbilical cord tissue from 20 preterm infants with BPD and 34 preterm infants without BPD were downloaded from the Gene Expression Omnibus databases. Random forest and LASSO regression were conducted to identify diagnostic FRLs. Nomogram was used to construct a predictive BPD model based on the FRLs. Finally, umbilical cord blood lymphocytes of preterm infants born before 32 weeks gestational age and term infants were collected and determined the expression level of diagnostic FRLs by RT-qPCR. RESULTS: Increased iron accumulation and several dysregulated ferroptosis-associated genes were found in BPD rat lung tissues, indicating that ferroptosis was participating in the development of BPD. By exploring the microarray dataset of preterm infants with BPD, 6 FRLs, namely LINC00348, POT1-AS1, LINC01103, TTTY8, PACRG-AS1, LINC00691, were determined as diagnostic FRLs for modeling. The area under the receiver operator characteristic curve of the model was 0.932, showing good discrimination of BPD. In accordance with our analysis of microarray dataset, the mRNA levels of FRLs were significantly upregulated in umbilical cord blood lymphocytes from preterm infants who had high risk of BPD. CONCLUSION: The incorporation of FRLs into a predictive model offers a non-invasive approach to show promise in improving early detection and management of this challenging chronic lung disease in premature infant, enabling timely intervention and personalized treatment strategies.

Analysis on the characteristics and relationships of lower limbs strength and power of sailors in different positions and levels.

Hikers and trapeze sailors are two main Olympic groups based on their specific role during sail racing. This study was to analyze the characteristics and relationships of lower limbs strength and power of hikers and trapeze sailors with different levels. Forty-five hikers and trapeze sailors were divided into high-level and low-level groups, respectively. The isokinetic dynamometer was used to measure sailors' lower limbs strength. Concentric and eccentric peak torque (PT) were measured for hamstrings and quadriceps at 60°/s, and isometric knee extensions at 45° knee flexion (0° = full extension). The counter movement jump (CMJ) was performed by Kistler to reflect sailors' lower limbs power. The results showed the hikers had higher quadriceps isometric PT, and male hikers had higher concentric and eccentric PT compared to trapeze sailors (p<0.05). For female sailors, the quadriceps' concentric, eccentric and isometric PT of high-level group were higher than low-level group' (p<0.05). The sailors' conventional and functional H/Q ratio ranged from 0.44 to 0.56 and 0.52 to 0.65, respectively. High-level and low-level groups had no difference in CMJ, which was moderately to strongly correlated with the isokinetic strength (r ranging 0.50-0.81, p<0.01). These findings suggest that long-term training can induce specificity in lower limbs strength of sailors. Hikers have better quadriceps isometric strength compared to trapeze sailors. The quadriceps concentric and eccentric PT can be used as parameters to distinguish between high-level and low-level sailors, but CMJ cannot.

Transformation kinetics of exogenous lead in an acidic soil during anoxic-oxic alteration: Important roles of phosphorus and organic matter.

Lead (Pb) can enter soil environment during flooding events such as surface runoff and intensive rainfall. However, the key transformation processes of exogenous Pb during anoxic-oxic alteration remain poorly understood particularly how phosphorus and organic matter contribute to Pb immobilization/release. Here, a kinetic model was established to investigate the Pb transformation in an acidic soil with two levels of Pb contamination under alternating anoxic-oxic conditions, based on the results of seven-step sequential extraction, dissolved organic carbon, sulfate, iron, phosphorus, and surface sites. Results showed that the potentially available Pb, including dissolved, exchangeable, and specifically adsorbed fractions, was gradually transferred to the fulvic complex, Fe-Mn oxides bound, and sulfides bound Pb after 40-day incubation under anoxic conditions, while the fulvic complex Pb further increased after 20-day incubation under oxic conditions. The concentration of phosphorus that was extracted by 0.5 M HCl or 0.03 M NH4F in 0.025 M HCl increased under anoxic conditions and decreased under oxic conditions. When Pb-binding to phosphorus is considered during kinetic modeling, the simulated results of Pb transformation suggest that phosphorus is more important than organic matter for Pb immobilization under anoxic conditions, while the phosphates, Fe-Mn oxides, and sulfides immobilized Pb is slowly released and then complexed by fulvic acids during the re-immobilization of dissolved organic matter in soil under oxic conditions. The model established with low Pb level has been successfully applied to describe the Pb transformation with high Pb level. This study provides a comprehensive understanding of the roles of phosphorus and organic matter in controlling Pb transformation in soil from kinetic modeling.

New perspective on effect of ß-cyclodextrin on nitrification-denitrification and denitrification phosphorus removal in biogenic manganese oxides driven moving bed biofilm reactor: Performance evaluation, microbial community and process.

Effect of ß-cyclodextrin (ß-CD) on simultaneous removal of NH4+-N, NO3--N, COD, and phosphorus (P) in biogenic manganese oxides (BioMnOx) driven moving bed biofilm reactor (MBBR) was investigated. 58.64% and 86.32%, 79.65% and 98.39%, 62.45% and 97.30%, and 24.80% and 95.90% of TN and COD were removed in phases I-IV, indicating that simultaneous nitrification and denitrification (SND) efficiencies were 75.44%, 83.91%, 72.71%, and 35.83%, respectively. Composition and fluorescence spectral characteristics of extracellular polymeric substance (EPS) were evaluated including the removal kinetics of TN and COD. Metabolic activity of Mn2+, decolorization performance of BioMnOx, and reactive oxygen species (ROS) characteristics were determined in biofilm. Furthermore, intermediate Mn3+ and BioMnOx concentration were analyzed. Finally, the removal process of nitrogen (N) and P was proposed based on characterizations of elemental characterization, electrochemistry, and microbial community. This study provides new insights into the N and P removal mediated by BioMnOx and ß-CD.

New polyketides and sesquiterpenoids from the deep-sea sulphide-derived fungus Phoma sp. 3A00413.

Phoma fungi are known to produce a diverse range of natural products which possess various biological activities such as antifungal, antimicrobial, insecticidal, cytotoxic, and immunomodulatory effects. In our present study, we have isolated two novel polyketides (1 and 3), one new sesquiterpenoid (2), and eight known compounds (4-11) from the culture of Phoma sp. 3A00413, a deep-sea sulphide-derived fungus. The structures of compounds 1-3 were elucidated using NMR, MS, NMR calculation, and ECD calculation. In vitro antibacterial activities of all the isolated compounds were evaluated against Escherichia coli, Vibrio parahaemolyticus vp-HL, Vibrio parahaemolyticus, Staphylococcus aureus, Vibrio vulnificus, and Salmonella enteritidis. Compounds 1, 7, and 8 exhibited weak inhibition against Staphylococcus aureus growth, while compounds 3 and 7 showed weak inhibition against Vibrio vulnificus growth. Importantly, compound 3 demonstrated exceptional potency against Vibrio parahaemolyticus, with a minimum inhibitory concentration (MIC) of 3.1 µM.

Performance of nitrification-denitrification and denitrifying phosphorus removal driven by in-situ generated biogenic manganese oxides in a moving bed biofilm reactor.

Simultaneous removal of NH4+-N, NO3--N, COD, and P by manganese redox cycling in nutrient wastewater was established with two moving bed biofilm reactors (MBBRs) with in-situ generated biogenic manganese oxides (BioMnOx) and non-BioMnOx. In-situ generated BioMnOx preferentially promoted the denitrification, and the average removal of NO3--N, NH4+-N, and TN in the experimental MBBR with BioMnOx increased to 89.00%, 70.64%, and 76.06% compared with the control MBBR with non-BioMnOx. The relevant enzymes activity, extracellular polymeric substance (EPS), electron transport system activity (ETSA), and reactive oxygen species (ROS) were investigated. The element valence and morphology of purified BioMnOx were characterized by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM), as well as the effect of BioMnOx on nitrogen and phosphorus removal. The results suggested that BioMnOx could improve nitrogen conversion. Electrochemical characteristic and microbial community were detected. This study provided a new strategy for nutrients removal in BioMnOx-mediated wastewater treatment.

Cadmium isotope fractionation and gene expression evidence for tracking sources of Cd in grains during grain filling in a soil-rice system.

Grain filling is the key period that causes excess cadmium (Cd) accumulation in rice grains. Nevertheless, uncertainties remain in distinguishing the multiple sources of Cd enrichment in grains. To better understand the transport and redistribution of Cd to grains upon drainage and flooding during grain filling, Cd isotope ratios and Cd-related gene expression were investigated in pot experiments. The results showed that the Cd isotopes in rice plants were much lighter than those in soil solutions (∆114/110Cdrice-soil solution = -0.36 to -0.63 ‰) but moderately heavier than those in Fe plaques (∆114/110Cdrice-Fe plaque = 0.13 to 0.24 ‰). Calculations revealed that Fe plaque might serve as the source of Cd in rice (69.2 % to 82.6 %), particularly upon flooding at the grain filling stage (82.6 %). Drainage at the grain filling stage yielded a larger extent of negative fractionation from node I to the flag leaves (∆114/110Cdflag leaves-node I = -0.82 ± 0.03 ‰), rachises (∆114/110Cdrachises-node I = -0.41 ± 0.04 ‰) and husks (∆114/110Cdrachises-node I = -0.30 ± 0.02 ‰), and significantly upregulated the OsLCT1 (phloem loading) and CAL1 (Cd-binding and xylem loading) genes in node I relative to that upon flooding. These results suggest that phloem loading of Cd into grains and transport of Cd-CAL1 complexes to flag leaves, rachises and husks were simultaneously facilitated. Upon flooding of grain filling, the positive fractionation from the leaves, rachises and husks to the grains (∆114/110Cdflag leaves/rachises/husks-node I = 0.21 to 0.29 ‰) is less pronounced than those upon drainage (∆114/110Cdflag leaves/rachises/husks-node I = 0.27 to 0.80 ‰). The CAL1 gene in flag leaves is down-regulated relative to that upon drainage. Thus, the supply of Cd from the leaves, rachises and husks to the grains is facilitated during flooding. These findings demonstrate that the excess Cd was purposefully transported to grain via xylem-to-phloem within nodes I upon the drainage during grain filling, and the expression of genes responsible for encoding ligands and transporters together with isotope fractionation could be used to tracking the source of Cd transported to rice grain.

Characterization and catalytic mechanism of a direct demethylsulfide hydrolase for catabolism of the methylthiol-s-triazine prometryn.

Demethylthio is one of the most important ways for microorganisms to metabolize triazine herbicides. Previous studies have found that the initial reaction of prometryn catabolism in Leucobacter triazinivorans JW-1 was the hydroxylation of its methylthio group, however, the corresponding functional enzyme was not yet clear. In this study, the gene proA was responsible for the initial step of prometryn catabolism from the strain JW-1 was cloned and expressed, and the purified amidohydrolases ProA have the ability to transform prometryn to 2-hydroxypropazine and methanethiol. The optimized reaction temperature and pH of ProA were 45 °C and 7.0, respectively, and the kinetic constants Km and Vmax of ProA for the catalysis of prometryn were 32.6 µM and 0.09 µmol/min/mg, respectively. Molecular docking analyses revealed that different catalysis efficiency of ProA and TrzN (Nocardioides sp. C190) for prometryn and atrazine was due to non-covalent changes in amino acid residues. Our findings provide new insights into the understanding of s-triazine catabolism at the molecular level.

Analysis of sailing variables and performance of laser sailors with different rankings under the condition of certain wind speed.

Objective: The aims of this study were to describe the characteristics of sailing variables and differences between different ranking sailors under the condition of certain wind speed, and predict the variables that affect performance. Methods: Five regatta's data of the 2019-2020 Hempel World Cup Series and Tokyo 2020 Olympic Games for a total of 63 races were analyzed in this study. The wind speed was defined as light wind below 8 knots, medium wind at 8-12 knots and strong wind above 12 knots. Sailors were divided into top 10 and other ranked groups based on their performance for each race. Results: 1) The race time of Laser class was about 50 min. The sailing distance traveled, VMG, percentage of upwind time, and the number of downwind maneuvers increased with an increase in the wind speed, while upwind maneuvers decreased increasing wind speed. Under the same wind speed, the VMG of reaching legs was the highest, followed by downwind and upwind legs in same wind speed. (2) The top 10 sailors had a high VMG, less race time, upwind/reaching legs' time and distance compared to other ranked sailors in all categories of wind speed (p < 0.05). There was no significant difference in the number of maneuvers among sailors of different rankings (p > 0.05). (3) There was a moderate to high correlation between first upwind mark position of sailors and the race ranking (r ranging 0.762-0.851, p < 0.01), and the top 10 sailors' first upwind ranking was close to the race performance. Conclusions: Wind speeds affect sailing variables and race characteristics. VMG and time and distance in upwind and reaching legs are important variables for differentiating sailors' level. Regardless of the wind speed, the first upwind mark position of sailors can be used as an effective factor in predicting the performance of the race.

Performance of simultaneous nitrification-denitrification and denitrifying phosphorus and manganese removal by driving a single-stage moving bed biofilm reactor based on manganese redox cycling.

Simultaneous removal of NH4+-N, NO3--N, COD, and P by manganese redox cycling in nutrient wastewater was established with a single-stage moving bed biofilm reactor (MBBR) under low C/N ratio. When sodium succinate replaced the conventional denitrifying carbon source, removal efficiencies of TN, NO3--N, NH4+-N, TP, and Mn2+ were 65.13 %, 79.63 %, 92.79 %, 51.57 %, and 68.10 %, respectively. Based on modified Stover-Kincannon model, 11.03 and 10.05 mg TN·L-1·h-1 of Umax values were obtained with sodium acetate and sodium succinate as substrates. Extracellular polymeric substances were used to evaluate the characteristics of biofilm, and microbial community of biofilm was identified. Transformation processes of NO3--N, NH4+-N, Mn2+, and P were investigated, suggesting that the main functional groups (e.g., CO, Mn-O, and CN bonds) participated in N, P, and Mn2+ removal, and MnO2 was the main component of biogenic manganese oxides. This study provides a new strategy for nutrients removal by Mn2+ driven MBBR.