Exercise snacks are a time-efficient alternative to moderate-intensity continuous training for improving cardiorespiratory fitness but not maximal fat oxidation in inactive adults: a randomized controlled trial.

The aims of this study were (1) to determine how stair-climbing-based exercise snacks (ES) compared to moderate-intensity continuous training (MICT) for improving cardiorespiratory fitness (CRF), and (2) to explore whether ES could improve maximal fat oxidation rate (MFO) in inactive adults. Healthy, young, inactive adults (n: 42, age: 21.6 ± 2.3 years, BMI: 22.5 ± 3.6 kg·m-2, peak oxygen uptake (VO2peak): 33.6 ± 6.3 mL·kg-1·min-1) were randomly assigned to ES, MICT, or Control. ES (n = 14) and MICT (n = 13) groups performed three sessions per week over 6 weeks, while the control group (n = 15) maintained their habitual lifestyle. ES involved 3 × 30 s "all-out" stair-climbing (6 flight, 126 steps, and 18.9 m total height) bouts separated by >1 h rest, and MICT involved 40 min × 60%-70% HRmax stationary cycling. A significant group × time interaction was found for relative VO2peak (p < 0.05) with ES significantly increasing by 7% compared to baseline (MD = 2.5 mL·kg-1·min-1 (95% CI = 1.2, 3.7), Cohen's d = 0.44), while MICT had no significant effects (MD = 1.0 mL·kg-1·min-1 (-1.1, 3.2), Cohen's d = 0.17), and Control experienced a significant decrease (MD = -1.7 mL·kg-1·min-1 (-2.9, -0.4), Cohen's d = 0.26). MFO was unchanged among the three groups (group × time interaction, p > 0.05 for all). Stair climbing-based ES are a time-efficient alternative to MICT for improving CRF among inactive adults, but the tested ES intervention appears to have limited potential to increase MFO.

Testing the mediatory role of kinesiophobia in the association between perceived greenspace and physical activity among individuals with chronic low back pain.

To test the mediatory role of kinesiophobia between greenspace and physical activity, we conducted a cross-sectional survey and recruited 801 participants with chronic low back pain. The level of greenspace was assessed using both perceived greenspace and the Normalized Difference Vegetation Index (NDVI). The frequency of walking and moderate and vigorous physical activities was measured using a brief assessment, while kinesiophobia was evaluated using the 11-item Tampa Scale for Kinesiophobia (TSK-11). The results revealed that perceived greenspace was positively associated with all measured physical activities, and was negatively associated with kinesiophobia. Meanwhile, NDVI was only positively associated with moderate and vigorous physical activity. Kinesiophobia played a marginal but significant mediating role in the association of perceived greenspace with walking, moderate physical activity, and vigorous physical activity. In conclusion, our findings offer early evidence of associations and pathways between greenspace and physical activity among individuals with chronic low back pain.

The Impact of Different Intensities of Physical Activity on Serum Urate and Gout: A Mendelian Randomization Study.

Physical activity is a potential protective factor against gout, but the role of exercise intensity in this context remains unclear. To overcome the limitations of observational studies in causal inference, this study employed a two-sample Mendelian randomization approach to explore the impact of different genetically proxied/predicted intensities of physical activity on serum urate concentration and the incidence of gout. Our data related to physical activity, serum urate, and gout were obtained from the UK Biobank, the Global Urate Genetics Consortium (GUGC), and the FinnGen dataset, respectively. Walking was included as representative of typical low-intensity physical activity in the analysis, and the other two types were moderate and vigorous physical activities. The estimation methods we used included the inverse-variance-weighted (IVW) method, MR-Egger regression, weighted-median method, simple-mode method, and weighted-mode method. Sensitivity analyses involved Rucker's framework, Cochran's Q test, funnel plots, MR-PRESSO outlier correction, and leave-one-out analysis. We found suggestive evidence from the inverse-variance-weighted method that moderate physical activity was a potential factor in reducing the incidence of gout (OR = 0.628, p = 0.034), and this association became more substantial in our subsequent sensitivity analysis (OR = 0.555, p = 0.006). However, we observed no distinctive effects of physical activity on serum urate concentration. In conclusion, our study supports some findings from observational studies and emphasizes the preventive role of moderate physical activity against gout. Given the limitations of the existing datasets, we call for future reexamination and expansion of our findings using new GWAS data.

A Low-Cost Inertial Measurement Unit Motion Capture System for Operation Posture Collection and Recognition.

In factories, human posture recognition facilitates human-machine collaboration, human risk management, and workflow improvement. Compared to optical sensors, inertial sensors have the advantages of portability and resistance to obstruction, making them suitable for factories. However, existing product-level inertial sensing solutions are generally expensive. This paper proposes a low-cost human motion capture system based on BMI 160, a type of six-axis inertial measurement unit (IMU). Based on WIFI communication, the collected data are processed to obtain the displacement of human joints' rotation angles around XYZ directions and the displacement in XYZ directions, then the human skeleton hierarchical relationship was combined to calculate the real-time human posture. Furthermore, the digital human model was been established on Unity3D to synchronously visualize and present human movements. We simulated assembly operations in a virtual reality environment for human posture data collection and posture recognition experiments. Six inertial sensors were placed on the chest, waist, knee joints, and ankle joints of both legs. There were 16,067 labeled samples obtained for posture recognition model training, and the accumulated displacement and the rotation angle of six joints in the three directions were used as input features. The bi-directional long short-term memory (BiLSTM) model was used to identify seven common operation postures: standing, slightly bending, deep bending, half-squatting, squatting, sitting, and supine, with an average accuracy of 98.24%. According to the experiment result, the proposed method could be used to develop a low-cost and effective solution to human posture recognition for factory operation.

Is low-volume high-intensity interval training a time-efficient strategy to improve cardiometabolic health and body composition? A meta-analysis.

The present meta-analysis aimed to assess the effects of low-volume high-intensity interval training (LV-HIIT; i.e., ≤5 min high-intensity exercise within a ≤15 min session) on cardiometabolic health and body composition. A systematic search was performed in accordance with PRISMA guidelines to assess the effect of LV-HIIT on cardiometabolic health and body composition. Twenty-one studies (moderate to high quality) with a total of 849 participants were included in this meta-analysis. LV-HIIT increased cardiorespiratory fitness (CRF, SMD = 1.19 [0.87, 1.50]) while lowering systolic blood pressure (SMD = -1.44 [-1.68, -1.20]), diastolic blood pressure (SMD = -1.51 [-1.75, -1.27]), mean arterial pressure (SMD = -1.55 [-1.80, -1.30]), MetS z-score (SMD = -0.76 [-1.02, -0.49]), fat mass (kg) (SMD = -0.22 [-0.44, 0.00]), fat mass (%) (SMD = -0.22 [-0.41, -0.02]), and waist circumference (SMD = -0.53 [-0.75, -0.31]) compared to untrained control (CONTROL). Despite a total time-commitment of LV-HIIT of only 14%-47% and 45%-94% compared to moderate-intensity continuous training and HV-HIIT, respectively, there were no statistically significant differences observed for any outcomes in comparisons between LV-HIIT and moderate-intensity continuous training (MICT) or high-volume HIIT. Significant inverse dose-responses were observed between the change in CRF with LV-HIIT and sprint repetitions (ß = -0.52 [-0.76, -0.28]), high-intensity duration (ß = -0.21 [-0.39, -0.02]), and total duration (ß = -0.19 [-0.36, -0.02]), while higher intensity significantly improved CRF gains. LV-HIIT can improve cardiometabolic health and body composition and represent a time-efficient alternative to MICT and HV-HIIT. Performing LV-HIIT at a higher intensity drives higher CRF gains. More repetitions, longer time at high intensity, and total session duration did not augment gains in CRF.

Removal of nitrate nitrogen by Pseudomonas JI-2 under strong alkaline conditions: Performance and mechanism.

The nitrate nitrogen removal characteristics of Pseudomonas JI-2 under strong alkaline conditions and the composition and functional groups of extracellular polymeric substance were analyzed. Furthermore, nontargeted metabonomics and bioinformatics technology were used to investigate the alkaline tolerance mechanism. JI-2 removed 11.05 mg N/(L·h) of nitrate with the initial pH, carbon to nitrogen ratio and temperature were 11.0, 8 and 25 °C respectively. Even when the pH was maintained at 11.0, JI-2 could still effectively remove nitrate. JI-2 contains a large number of Na+/H+ antiporters, such as Mrp, Mnh (mnhACDEFG) and Pha (phaACDEFG), which can stabilize the intracellular acid-base environment, and SlpA can enable quick adaptation to alkaline conditions. Moreover, JI-2 responds to the strong alkaline environment by secreting more polysaccharides, acidic functional groups and compatible solutes and regulating key metabolic processes such as pantothenate and CoA biosynthesis and carbapenem biosynthesis. Therefore, JI-2 can survive in strong alkaline environments and remove nitrate efficiently.

Chronic high-intensity interval training and moderate-intensity continuous training are both effective in increasing maximum fat oxidation during exercise in overweight and obese adults: A meta-analysis.

Objective: to (1) systematically review the chronic effect of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on maximal fat oxidation (MFO) in overweight and obese adults, and (2) explore MFO influencing factors and its dose-response relationships with HIIT and MICT. Methods: Studies using a between-group design involving overweight and obese adults and assessing the effect of HIIT and MICT on MFO were included. A meta-analysis on MFO indices was conducted, and the observed heterogeneities were explored through subgroup, regression, and sensitivity analyses. Results: Thirteen studies of moderate to high quality with a total of 519 overweight and obese subjects were included in this meta-analysis (HIIT, n = 136; MICT, n = 235; Control, n = 148). HIIT displayed a statistically significant favorable effect on MFO compared to no-training (MD = 0.07; 95%CI [0.03 to 0.11]; I2 = 0%). Likewise, MICT displayed a statistically significant favorable effect on MFO compared to no-training (MD = 0.10; 95%CI [0.06 to 0.15]; I2 = 95%). Subgroup and regression analyses revealed that exercise intensity (Fatmax vs. non-Fatmax; %VO2peak), exercise mode, BMI, and VO2peak all significantly moderated MICT on MFO. When analyzing studies that have directly compared HIIT and MCIT in obese people, it seems there is no difference in the MFO change (MD = 0.01; 95%CI [-0.02 to 0.04]; I2 = 64%). No publication bias was found in any of the above meta-analyses (Egger's test p > 0.05 for all). Conclusion: Both HIIT and MICT are effective in improving MFO in overweight and obese adults, and they have similar effects. MCIT with an intensity of 65-70% VO2peak, performed 3 times per week for 60 min per session, will optimize MFO increases in overweight and obese adults. Given the lack of studies examining the effect of HIIT on MFO in overweight and obese adults and the great diversity in the training protocols in the existing studies, we were unable to make sound recommendations for training.

Short-term effects of SARS-CoV-2 infection and return to sport on neuromuscular performance, body composition, and mental health - A case series of well-trained young kayakers.

Purpose: This study aimed to examine the short-term effects of SARS-CoV-2 infection and return to sport (RTS) on neuromuscular performance, body composition, and mental health in well-trained young kayakers. Methods: 17 vaccinated kayakers (8 male, 9 female) underwent body composition assessment, peak power output bench press (BP), and 40-s maximum repetition BP tests 23.9 ± 1.6 days before and 22.5 ± 1.6 days after a SARS-CoV-2 infection. A linear transducer was used to examine the BP performance. The perception of training load and mental health were quantified with Borg's CR-10 scale and the Hooper questionnaire before and after infection. The difference and relationship of variables were used Wilcoxon test, Student t-test, Pearson's, and Spearman's r correlation coefficients. Results: There was a significant increase in body mass, fat-free mass, and skeletal muscle mass, but no significant changes in body fat, fat mass, and all BP performance after infection (p < 0.05). There was a significant reduction in training hours per week, session rating of perceived exertion (sRPE), internal training load (sRPE-TL), fatigue, muscle soreness levels, and Hooper index, but no changes in sleep quality and stress levels after infection (p < 0.05). The training and mental health during the RTS period was significantly correlated (r = -0.85 to 0.70) with physical performance after infection. Conclusion: A SARS-CoV-2 infection did not appear to impair the upper-body neuromuscular performance and mental health of vaccinated well-trained young kayakers after a short-term RTS period. These findings can assist coaches, and medical and club staff when guiding RTS strategies after other acute infections or similar restrictions.

The presence of copper ions alters tetracycline removal pathway in aerobic granular sludge: Performance and mechanism.

This study investigated the removal characteristics of tetracycline (TC) in the presence of copper ions (Cu2+) in aerobic granular sludge by analyzing the TC removal pathway, composition and functional group changes of extracellular polymeric substances (EPS), and microbial community structure. The TC removal pathway changed from cell biosorption to EPS biosorption, and the microbial degradation rate of TC was reduced by 21.37% in the presence of Cu2+. Cu2+ and TC induced enrichment of denitrifying bacteria and EPS-producing bacteria by regulating the expression of signaling molecules and amino acid synthesis genes to increase the content of EPS and -NH2 groups in EPS. Although Cu2+ reduced the content of acidic hydroxyl functional groups (AHFG) in EPS, an increase in TC concentration stimulated the secretion of more AHFG and -NH2 groups in EPS. The long-term presence of TC presence of the relative abundances of Thauera, Flavobacterium and Rhodobacter and improved the removal efficiency.

The performance and mechanism of tetracycline and ammonium removal by Pseudomonas sp. DX-21.

To remove ammonium and tetracycline (TC) from wastewater, a new strain, DX-21, was isolated and exhibited simultaneous removal ability. The performance of DX-21 in TC removal, its removal mechanism, and the potential toxicities of the degradation products were investigated with genomics, mass spectrometry, density functional theory calculations, quantitative structure-activity relationship analyses, and Escherichia coli exposure experiments. DX-21 exhibited removal of ammonium (9.64 mg·L-1·h-1) via assimilation, and TC removal (0.85 mg·L-1·h-1) primarily occurred through cell surface bio-adsorption and biodegradation. Among the 12 identified degradation products, the majority exhibited lower toxicities than TC. Moreover, potential degradation pathways were proposed, including hydroxylation and deamination. Furthermore, DX-21 possessed TC resistance genes, various oxygenases and peroxidases that could potentially contribute to TC degradation. DX-21 colonized activated sludge and significantly enhanced the biodegradation of TC. Therefore, DX-21 showed potential for treating wastewater containing both ammonium and TC.

Association between Lower Body Qualities and Change-of-Direction Performance: A Meta-Analysis.

The aim of the present study is to determine the associations between lower body muscle strength qualities and change of direction (CoD) performance. Three databases were used to perform a systematic literature search up to September 30, 2022. Based on the studies that met the inclusion criteria, we calculated Pearson's r correlation coefficient to examine the relationships between muscle strength qualities and CoD performance. The quality of the studies included was evaluated by the modified version of the Downs and Black Quality Index Tool. Heterogeneity was determined via the Q statistic and I 2, and Egger's test was used to assess small study bias. The results revealed that lower body maximal strength (pooled: r=- 0.54, dynamic: r=- 0.60, static: r=- 0.41), joint strength (pooled: r=- 0.59, EXT-ecc: r=- 0.63, FLEX-ecc: r=- 0.59), reactive strength (r=- 0.42) and power (pooled: r=- 0.45, jump height: r=- 0.41, jump distance: r=- 0.60, peak power: r=- 0.41) were negatively and moderately related to CoD performance. To conclude, the results highlight that a number of muscle strength qualities are associated with CoD performance and are pertinent to specific phases of a directional change. It should be noted that the conclusions of this study do not establish causality, and further research is needed to better understand their training effects and underlying mechanisms.

Global trends and frontiers in research on exercise training for heart failure: a bibliometric analysis from 2002 to 2022.

Background: Heart failure is a common cardiovascular disease that imposes a heavy clinical and economic burden worldwide. Previous research and guidelines have supported exercise training as a safe, effective, and cost-efficient treatment to intervene in heart failure. The aim of this study was to analyze the global published literature in the field of exercise training for heart failure from 2002 to 2022, and to identify hot spots and frontiers within this research field. Methods: Bibliometric information on literature on the topic of exercise training for heart failure published between 2002 and 2022 was searched and collected in the Web of Science Core Collection. CiteSpace 6.1.R6 (Basic) and VOSviewer (1.6.18) were applied to perform bibliometric and knowledge mapping visualization analyses. Results: A total of 2017 documents were retrieved, with an upward-stable trend in the field of exercise training for heart failure. The US authors were in the first place with 667 documents (33.07%), followed by Brazilian authors (248, 12.30%) and Italian authors (182, 9.02%). The Universidade de São Paulo in Brazil was the institution with the highest number of publications (130, 6.45%). The top 5 active authors were all from the USA, with Christopher Michael O'Connor and William Erle Kraus publishing the most documents (51, 2.53%). The International Journal of Cardiology (83, 4.12%) and the Journal of Applied Physiology (78, 3.87%) were the two most popular journals, while Cardiac Cardiovascular Systems (983, 48.74%) and Physiology (299, 14.82%) were the two most popular categories. Based on the results of keyword co-occurrence network and co-cited reference network, the hot spots and frontiers of research in the field of exercise training for heart failure were high-intensity interval training, behaviour therapy, heart failure with preserved ejection fraction, and systematic reviews. Conclusion: The field of exercise training for heart failure has experienced two decades of steady and rapid development, and the findings of this bibliometric analysis provide ideas and references for relevant stakeholders such as subsequent researchers for further exploration.

Iron-loaded sludge biochar alleviates the inhibitory effect of tetracycline on anammox bacteria: Performance and mechanism.

The anaerobic ammonia oxidation (anammox) process is sensitive to environmental pollutants, such as antibiotics. In this study, the harmful effect of tetracycline (TC) on the performance of an anammox reactor and the mitigation of TC inhibition by iron-loaded sludge biochar (Fe-BC) were studied by analyzing extracellular polymeric substances (EPS), microbial community structure and functional genes. The total inorganic nitrogen (TIN) removal rate of the TC reactor was reduced by 5.86% compared to that of the control group, while that of the TC + Fe-BC reactor improved by 10.19% compared to that of the TC reactor. Adding Fe-BC increased the activity of anammox sludge by promoting the secretion of EPS (including protein, humic acids and c-Cyts). The results of the enzymolysis experiment showed that protein can improve the activity of anammox sludge, while the ability of polysaccharide to improve the activity of anammox was related to the treated enzymes. In addition, Fe-BC alleviated the inhibitory effect of TC by mediating the anammox electron transfer process. Furthermore, Fe-BC increased the absolute abundance of hdh and hzsB by 2.77 and 1.18 times compared to the TC reactor and improved the relative abundance of Candidatus Brocadia in the absence of TC. The addition of Fe-BC is an effective way to alleviate the inhibitory effect of TC on the anammox process.

Transcription analyses of differentially expressed mRNAs, lncRNAs, circRNAs, and miRNAs in the growth plate of rats with glucocorticoid-induced growth retardation.

Background: Glucocorticoids (GCs) are commonly used to treat autoimmune diseases and malignancies in children and adolescents. Growth retardation is a common adverse effect of GC treatment in pediatric patients. Accumulating evidence indicates that non-coding RNAs (ncRNAs) are involved in the pathogenesis of glucocorticoid-induced growth retardation (GIGR), but the roles of specific ncRNAs in growth remain largely unknown. Methods: In this study, 2-week-old male Sprague-Dawley rats had been treated with 2 mg/kg/d of dexamethasone for 7 or 14 days, after which the growth plate tissues were collected for high-throughput RNA sequencing to identify differentially expressed mRNAs, lncRNAs, circRNAs, and miRNAs in GIGR rats. Results: Transcriptomic analysis identified 1,718 mRNAs, 896 lncRNAs, 60 circRNAs, and 72 miRNAs with different expression levels in the 7d group. In the 14d group, 1,515 mRNAs, 880 lncRNAs, 46 circRNAs, and 55 miRNAs with differential expression were identified. Four mRNAs and four miRNAs that may be closely associated with the development of GIGR were further validated by real-time quantitative fluorescence PCR. Function enrichment analysis indicated that the PI3K-Akt signaling pathway, NF-kappa B signaling pathway, and TGF-ß signaling pathway participated in the development of the GIGR. Moreover, the constructed ceRNA networks suggested that several miRNAs (including miR-140-3p and miR-127-3p) might play an important role in the pathogenesis of GIGR. Conclusions: These results provide new insights and important clues for exploring the molecular mechanisms underlying GIGR.

The coexistence of copper ions and TC affected the binding ability and the reaction order between extracellular polymeric substances of aerobic granular sludge and exogenous substances.

As a barrier against external toxic effects, extracellular polymeric substances (EPSs) directly affect the toxicity and removal efficiency of exogenous substances. The reaction of EPSs with exogenous substances has been taken into consideration. The contents of EPSs in sludge cultivated by different influent water vary greatly, which leads to great differences in the binding ability and reaction sequence between EPSs and exogenous substances. However, the results in this respect are very limited. In this study, the binding characteristics between exogenous tetracycline (TC)/copper ions (Cu2+) and EPSs from aerobic granular sludge cultured under single and coexisting TC/Cu2+ were assessed by three-dimensional fluorescence-parallel factor analysis. The pollutants in the influent water could directionally induce microorganisms to secrete more EPSs, while fluorescence substances in EPSs could combine with the exogenous substances to lessen their effects. In the presence of coexisting TC and Cu2+ in the influent water, the ability of fluorescence substances in EPSs to combine with exogenous TC or Cu2+ weakened, and humic substances in EPSs were more susceptible than protein substances to binding with exogenous substances. However, the reaction order between EPSs components and exogenous TC or Cu2+ was opposite, and the ability of fluorescence substances in EPSs to combine with exogenous TC or Cu2+ was enhanced under individual TC or Cu2+ existing in the influent water. This study provided new insights into the interaction between EPSs and exogenous substances.

Using structural equation modeling to explore the influences of physical activity, mental health, well-being, and loneliness on Douyin usage at bedtime.

Douyin is the Chinese version of TikTok. Using Douyin at bedtime is a very common behavior among Douyin users. However, the reasons why users like using Douyin before sleep are yet unclear. We conducted a cross-section survey from January 1st to January 16th, 2023 to capture data to examine the associations of depression, anxiety, life satisfaction, well-being, loneliness, and physical activity with Douyin usage at bedtime. The mediation role of insomnia in these associations was examined. A total of 3,392 participants who met the inclusion criteria were included for analysis. Our structural equation modeling analysis showed that depression on (ß = 0.08; p < 0.05), anxiety (ß = 0.06; p < 0.05), and loneliness (ß = 0.14; p < 0.05) were directly associated with increased Douyin usage at bedtime, and were also indirectly associated with Douyin usage through insomnia (depression: ß = 0.18; p < 0.05, anxiety: ß = 0.16; p < 0.05, and loneliness: ß = 0.12; p < 0.05). Life satisfaction (ß = -0.05; p < 0.05) and well-being (ß = -0.20; p < 0.05) were directly associated with decreased Douyin usage at bedtime, and were also indirectly associated with Douyin usage through insomnia (life satisfaction: ß = -0.09; p < 0.05, and well-being: ß = -0.11; p < 0.05). However, physical activity was unexpectedly associated with increased Douyin usage at bedtime (ß = 0.20; p < 0.05). In conclusion, our findings shed new light on the specific reasons why Douyin users like using Douyin at bedtime.

Performance and mechanism of nitrate removal by the aerobic denitrifying bacterium JI-2 with a strong autoaggregation capacity.

Here, a new strain JI-2 of the strongly autoaggregating aerobic denitrifying bacteria was screened. The nitrate removal ability and autoaggregation mechanism of JI-2 were analyzed using the nitrogen balance and genomics technology. The nitrate removal rate was 27.05 mg N/(L·h) at pH 9.0 and C/N 8.0. The strain JI-2 removes nitrate via the aerobic denitrification and dissimilation pathways and removes ammonium via the assimilation pathway. 66.81 % nitrate was converted to cellular components under aerobic conditions. Complex nitrogen metabolism genes were detected in strain JI-2. C-di-GMP mediates the motility behavior of JI-2 by binding the FleQ and PilZ proteins, and regulating the expression of PslA. Furthermore, the mechanism of autoaggregation was verified by extracellular polymeric substance analysis. Meanwhile, the nitrate removal rates of strain JI-2 was 11.13-12.50 mg N/(L·h) in wastewater. Thus, strain JI-2 has good prospects for application in the treatment of nitrate wastewater.

Step feed mode synergistic mixed carbon source to improve sequencing batch reactor simultaneous nitrification and denitrification efficiency of domestic wastewater treatment.

The limited efficiency of nitrogen removal has traditionally hindered wide application of simultaneous nitrification and denitrification (SND) technology. Here, the nitrogen removal characteristics of a sequencing batch reactor were studied by adopting a strategy of a step-feeding mode, synergistic regional oxygen limitation, and a mixed carbon source. The changes of the microbial population succession and nitrogen metabolism functional genes were analyzed. This strategy provided a favorable level of dissolved oxygen and continuous carbon sources for driving the denitrification process. The total nitrogen removal efficiency and SND rate reached 92.60% and 96.49%, respectively, by regulating the ratio of sodium acetate to starch in the step feed to 5:1. This procedure increased the relative abundance of denitrifying functional genes and induced the growth of a variety of traditional denitrifying bacteria and aerobic denitrifying bacteria participating in the process of nitrogen removal. Overall, this work offers a new strategy for achieving efficient SND.

Performance and mechanism of tetracycline removal by the aerobic nitrate-reducing strain Pseudomonas sp. XS-18 with auto-aggregation.

The coexistence of multiple pollutants has become a distinctive feature of water pollution. However, there are a few strains that can remove nitrate and tetracycline (TC). Here, the efficiency of strain XS-18 in removing nitrate and TC was analyzed, and the mechanism of tolerance and removal of TC was investigated by infrared spectroscopy, three-dimensional fluorescence spectroscopy, and genome analysis. XS-18 could efficiently remove TC (0.40 mg·L-1·h-1) at pH 7.0-11.0 with auto-aggregation. TC was removed via extracellular polymeric substance (EPS) (55.90%) and cell surface (44.10%) adsorption. TC (10 mg/L) could stimulate XS-18 to secrete more polysaccharides and hydrophobic proteins to improve its auto-aggregation ability. The findings also confirmed that TC resistance genes were present. Furthermore, the bacterial flagellum, signal transduction of the chemotactic system and regulatory genes were shown to be related to the auto-aggregation of the strain. XS-18 has potential applications in the treatment of wastewater containing nitrate and TC.