POU5F1 promotes the proliferation, migration, and invasion of gastric cancer cells by reducing the ubiquitination level of TRAF6.

POU5F1 plays an important role in maintaining the cancer stem cell (CSC) -like properties of gastric cancer (GC) cells. The impact of POU5F1 on the proliferation and metastasis of GC was examined, along with the potential of ATRA as a specific therapeutic agent for GC. The dysregulation of POU5F1 expression in GC tissues was analyzed using public databases and bioinformatics techniques, and the disparity in POU5F1 expression between normal gastric tissues and GC tissues was further assessed through western blot, RT-qPCR, and immunohistochemistry. The present study aimed to investigate the impact of POU5F1 on the proliferation, migration, and invasion of GC cells through both in vivo and in vitro experiments. Additionally, the effects of ATRA on the proliferation, migration, and invasion of GC cells were examined using in vivo and in vitro approaches. Our findings revealed a significant upregulation of POU5F1 in GC tissues, which was found to be associated with a poorer prognosis in patients with GC. Moreover, POU5F1 was observed to enhance the proliferation, migration, and invasion of GC cells in vitro, as well as promote subcutaneous tumor growth and lung metastasis of GC cells in vivo. The overexpression of POU5F1 mechanistically triggers the process of Epithelial-mesenchymal transition (EMT) by down-regulating E-Cadherin and up-regulating N-Cadherin and VIM. POU5F1 hinders the ubiquitination of TRAF6 through negative regulation of TRIM59, thereby facilitating the activation of the NF-κB pathway. Furthermore, the administration of ATRA effectively impedes the proliferation, migration, and invasion of GC cells by suppressing the expression of POU5F1. The upregulation of POU5F1 elicits EMT, fosters the initiation of the NF-κB signaling pathway in GC cells, and stimulates the proliferation, invasion, and metastasis of GC cells. All-trans retinoic acid (ATRA) can impede these POU5F1-induced effects, thereby potentially serving as an adjunctive therapeutic approach for GC.

Fibroblast growth factor 15, induced by elevated bile acids, mediates the improvement of hepatic glucose metabolism after sleeve gastrectomy.

BACKGROUND: Fibroblast growth factor (FGF) 15/19, which is expressed in and secreted from the distal ileum, can regulate hepatic glucose metabolism in an endocrine manner. The levels of both bile acids (BAs) and FGF15/19 are elevated after bariatric surgery. However, it is unclear whether the increase in FGF15/19 is induced by BAs. Moreover, it remains to be understood whether FGF15/19 elevations contribute to improvements in hepatic glucose metabolism after bariatric surgery. AIM: To investigate the mechanism of improvement of hepatic glucose metabolism by elevated BAs after sleeve gastrectomy (SG). METHODS: By calculating and comparing the changes of body weight after SG with SHAM group, we examined the weight-loss effect of SG. The oral glucose tolerance test (OGTT) test and area under the curve of OGTT curves were used to assess the anti-diabetic effects of SG. By detecting the glycogen content, expression and activity of glycogen synthase as well as the glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (Pepck), we evaluated the hepatic glycogen content and gluconeogenesis activity. We examined the levels of total BA (TBA) together with the farnesoid X receptor (FXR)-agonistic BA subspecies in systemic serum and portal vein at week 12 post-surgery. Then the histological expression of ileal FXR and FGF15 and hepatic FGF receptor 4 (FGFR4) with its corresponding signal pathways involved in glucose metabolism were detected. RESULTS: After surgery, food intake and body weight gain of SG group was decreased compare with the SHAM group. The hepatic glycogen content and glycogen synthase activity was significantly stimulated after SG, while the expression of the key enzyme for hepatic gluconeogenesis: G6Pase and Pepck, were depressed. TBA levels in serum and portal vein were both elevated after SG, the FXR-agonistic BA subspecies: Chenodeoxycholic acid (CDCA), lithocholic acid (LCA) in serum and CDCA, DCA, LCA in portal vein were all higher in SG group than that in SHAM group. Consequently, the ileal expression of FXR and FGF15 were also advanced in SG group. Moreover, the hepatic expression of FGFR4 was stimulated in SG-operated rats. As a result, the activity of its corresponding pathway for glycogen synthesis: FGFR4-Ras-extracellular signal regulated kinase pathway was stimulated, while the corresponding pathway for hepatic gluconeogenesis: FGFR4- cAMP regulatory element-binding protein- peroxisome proliferator-activated receptor γ coactivator-1α pathway was suppressed. CONCLUSION: Elevated BAs after SG induced FGF15 expression in distal ileum by activating their receptor FXR. Furthermore, the promoted FGF15 partly mediated the improving effects on hepatic glucose metabolism of SG.

Simultaneous removal of phosphate, calcium, and ammonia nitrogen in a hydrogel immobilized reactor with bentonite/lanthanum/PVA based on microbial induced calcium precipitation.

In recent years, it is urgent to solve nitrogen and phosphorus pollution in domestic wastewater. The target strain Pseudomonas sp. Y1 was immobilized using polyvinyl alcohol (PVA) matrix coupled with bentonite and lanthanum (La), respectively, to fabricate four hydrogel materials that used to construct bioreactors. The optimal operating parameters and dephosphorization mechanism were discussed, and the effects of hydrogel materials and different loads on the performance of the bioreactor were contrastively analyzed. The results manifested that when the hydraulic retention time (HRT) was 6.0 h, the C/N was 6.0, and the Ca2+ concentration was 100.0 mg L-1, the bioreactors had the best heterotrophic nitrification-aerobic denitrification (HNAD) and biomineralization capacity, and the maximum removal efficiencies of Ca2+, PO43--P, and NH4+-N were 82.57, 99.17, and 89.08%, respectively. The operation data indicated that the addition of bentonite significantly promoted HNAD, and the bioreactor had stronger dephosphorization ability in the presence of La. The main phosphorous removal mechanisms were confirmed to be adsorption and co-precipitation. Finally, high-throughput sequencing results indicated that Pseudomonas accounted for the paramount proportion in the bioreactor, and the prediction of functional genes indicated that the C/N of 6.0 is more favorable for the expression of nitrogen removal-related functional genes in the bioreactor system. This study highlights the superiority of microbial induced calcium precipitation (MICP) combined with PVA hydrogel, and provides a theoretical basis for simultaneous nitrogen and phosphate removal of wastewater.

Microbially induced calcium precipitation driven by denitrification: Performance, metabolites, and molecular mechanisms.

Microbially induced calcium precipitation (MICP) driven by denitrification has attracted extensive attention due to its application potential in nitrate removal from calcium-rich groundwater. However, little research has been conducted on this technique at the molecular level. Here, Pseudomonas WZ39 was used to explore the molecular mechanisms of nitrate-dependent MICP and the effects of Ca2+ on bacterial transcriptional regulation and metabolic response. The results exhibited that appropriate Ca2+ concentration (4.5 mM) can promote denitrification and the production of ATP, EPSs, and SMPs. Genome-wide analysis showed that the nitrate-dependent MICP was accomplished through heterotrophic denitrification and CO2 capture. During this process, EPS biosynthesis and Ca2+ signaling regulation were involved in the nucleation template supply and Ca2+ homeostasis balance. Untargeted transcriptome- and metabolome-association analyses revealed that the addition of Ca2+ triggered the significant up-regulation in several key pathways, such as transmembrane transporter and channel activities, amino acid metabolism, fatty acid biosynthesis, and carbon metabolism, which played a momentous role in the mineral nucleation and energy provision. The detailed information provided novel insights for understanding the active control of bacteria on MICP, and has great significance for deepening the cognition of groundwater remediation using nitrate-dependent MICP technique.

Simultaneous removal of ammonia nitrogen, recovery of phosphate, and immobilization of nickel in a polyester fiber with shell powder and iron carbon spheres bioreactor: Optimization and pathways mechanism.

Composite pollutants are prevalent in wastewater, whereas, the simultaneous accomplishment of efficient nitrogen removal and resources recovery remains a challenge. In this study, a bioreactor was constructed to contain Pseudomonas sp. Y1 using polyester fiber wrapped with shell powder and iron carbon spheres, achieving ammonia nitrogen (NH4+-N) removal, phosphate (PO43--P) recovery, and nickel (Ni2+) immobilization. The optimal performance of bioreactor was average removal efficiencies of NH4+-N, PO43--P, calcium (Ca2+), and Ni2+ as 82.42, 96.67, 76.13, and 98.29% at a hydraulic retention time (HRT) of 6 h, pH of 7.0, and influent Ca2+ and Ni2+ concentrations of 100.0 and 3.0 mg L-1, respectively. The bioreactor could remove PO43--P, Ca2+, and Ni2+ by biomineralization, co-precipitation, adsorption, and lattice substitution. Moreover, microbial community analysis suggested that Pseudomonas was the predominant genus and had possessed tolerance to Ni2+ toxicity in wastewater. This study presented an effective method to synchronously remove NH4+-N, recover PO43--P, and fix heavy metals through microbially induced carbonate precipitation (MICP) and heterotrophic nitrification and aerobic denitrification (HNAD) technology.

Microbially induced calcium precipitation coupled with medical stone-coated sponges: A targeted strategy for enhanced nitrate and fluoride removal from groundwater.

The coexistence of nitrate and fluoride in groundwater is of high concern due to its potential environmental impacts and health risks. Medical stone-coated sponges, as a microbial activity promoter and slow-release calcium source, were introduced into an immobilized bioreactor for enhanced removal of nitrate and fluoride. Under the hydraulic retention time of 3 h, nitrate, fluoride, and calcium contents of 16.5, 3.0, and 100 mg L-1, the average removal efficiencies of nitrate, fluoride, and calcium reached 99.49%, 74.26%, and 70.43%, respectively. Co-precipitation and chemisorption were the mechanisms for fluoride and calcium removal. Medical stone load improved the competitiveness of dominant bacteria and electron transport activity, accelerated the denitrification process, and stimulated biofilm formation. High fluoride level (5.0 mg L-1) inhibited the nitrate removal and aromatic protein production. The fluoride content changes altered the carbon source preference of the microbial community, which preferred to use amino acids and carbohydrates under a higher fluoride content. The introduction of medical stones significantly accelerated the fluoride and nitrate removal, providing a new insight for the application of microbially induced calcium precipitation technique in the remediation of low-calcium groundwater.

Synchronous removal of ammonia nitrogen, phosphate, and calcium by heterotrophic nitrifying strain Pseudomonas sp. Y1 based on microbial induced calcium precipitation.

Pseudomonas sp. Y1, a strain with superior synchronous removal ability of ammonia nitrogen (NH4+-N), phosphate (PO43--P), and calcium (Ca2+) was isolated, with the removal efficiencies of 92.04, 99.98, and 83.40 %, respectively. Meanwhile, the chemical oxygen demand (COD) was degraded by 90.33 %. Through kinetic analysis, the optimal cultivated conditions for heterotrophic nitrification-aerobic denitrification (HNAD) and biomineralization were determined. The growth curves experimental results of different nitrogen sources indicated that strain Y1 could remove NH4+-N through HNAD. The results of excitation-emission matrix (EEM) proved that the appearance of extracellular polymeric substances (EPS) promoted the precipitation of phosphate minerals. Finally, the characterization results of the bioprecipitates showed that the HNAD process produced the alkalinity required for microbial induced calcium precipitation (MICP), resulting in the removal of PO43- via adsorption and co-precipitation. This study provides a theoretical basis for the application of microorganisms to achieve synchronous nutrient removal and phosphorus recovery in wastewater.

Simultaneous removal of nitrate and heavy metals in a biofilm reactor filled with modified biochar.

A biofilm reactor filled with chia seeds gum modified biochar was set up for the simultaneous removal of nitrate, cadmium and zinc from calcium-containing wastewater via denitrification and microbially-induced (calcium) carbonate precipitation. The reactor performance was studied under different conditions of pH, Cd concentration, and hydraulic retention time. The optimal removal efficiency of the reactor for NO3--N, Ca2+, Cd2+, and Zn2+ were 99.98, 79.89, 100, and 99.84 %, respectively. 3D-EEM indicated the aromatic compounds confirming the stability of the reactor. FTIR illustrated the presence of -OH, CaCO3, C-O-C, and C-O-H indicating the precipitation and role of gum in MICP. SEM confirmed that the seed crystal induced the repeated crystallization of free metal ions. XRD showed that heavy metals were removed in the form of CaCO3, CdCO3, ZnCO3, Ca3(PO3)2, Cd3(PO3)2, and Zn3(PO3)2 co-crystallization. SEM-EDS showed the composition and distribution of elements. High-throughput sequencing showed that Curpriavidus sp. GMF1 and Ochrobactrum sp. GMC12 were the dominant bacterial species, with powerful denitrification and MICP mineralization capabilities.

Objective performance of emergency medical technicians in the use of mechanical cardiopulmonary resuscitation compared with subjective self-evaluation: a cross-sectional, simulation-based study.

OBJECTIVE: To evaluate the subjective and objective resuscitation performance of emergency medical technicians (EMTs) using mechanical cardiopulmonary resuscitation (MCPR) devices. DESIGN AND SETTING: This was a cross-sectional simulation-based study where participants installed the MCPR device on a training manikin. PARTICIPANTS: We assessed EMT-Intermediates (EMT-Is) and EMT-Paramedics (EMT-Ps) of the Emergency Medical Services (Ambulance) Division of the Taipei City Fire Department. PRIMARY AND SECONDARY OUTCOME MEASURES: The primary outcome was the gap between self-perceived (subjective) and actual (objective) no-flow time during resuscitation, which we hypothesised as statistically insignificant. The secondary outcome was the association between resuscitation performance and personal attributes like knowledge, attitude and self-confidence. RESULTS: Among 210 participants between 21 and 45 years old, only six were female. There were 144 EMT-Is and 66 EMT-Ps. During a simulated resuscitation lasting between four and a half and 5 min, EMTs had longer actual no-flow time compared with self-perceived no-flow time (subjective, 38 s; objective, 57.5 s; p value<0.001). This discrepancy could cause a 6.5% drop of the chest compression fraction in a resuscitation period of 5 min. Among the EMT personal factors, self-confidence was negatively associated with objective MCPR deployment performance (adjusted OR (aOR) 0.66, 95% CI 0.45 to 0.97, p=0.033) and objective teamwork performance (aOR 0.57, 95% CI 0.34 to 0.97, p=0.037) for EMT-Ps, whereas knowledge was positively associated with objective MCPR deployment performance (aOR 2.15, 95% CI 1.31 to 3.52, p=0.002) and objective teamwork performance (aOR 1.77, 95% CI 1.02 to 3.08, p=0.043) for EMT-Is. Moreover, regarding the self-evaluation of no-flow time, both self-satisfaction and self-abasement were associated with objectively poor teamwork performance. CONCLUSIONS: EMTs' subjective and objective performance was inconsistent during the MCPR simulation. Self-confidence and knowledge were personal factors associated with MCPR deployment and teamwork performance. Both self-satisfaction and self-abasement were detrimental to teamwork during resuscitation.

Enhanced removal of fluoride, nitrate, and calcium using self-assembled fungus-flexible fiber composite microspheres combined with microbially induced calcium precipitation.

Self-assembled fungus-flexible fiber composite microspheres (SFFMs) were firstly combined with microbially induced calcium precipitation (MICP) in a continuous-flow bioreactor and achieved the efficient removal of fluoride (F-), nitrate (NO3-), and calcium (Ca2+). Under the influent F- of 3.0 mg L-1, pH of 7.0, and HRT of 8 h, the average removal efficiencies reached 77.54%, 99.39%, and 67.25% (0.29, 2.03, and 8.34 mg L-1 h-1), respectively. Fluorescence spectrum and flow cytometry analyses indicated that F- content significantly affected the metabolism and viability of bacteria. SEM images showed that flexible fibers and intertwined hyphae provided effective locations for bacterial colonization in SFFMs. The precipitated products were characterized by XRD and FTIR, which revealed that F- was mainly removed in the form of calcium fluoride and calcium fluorophosphate (CaF2 and Ca5(PO4)3F). High-throughput analysis at different levels demonstrated that Pseudomonas sp. WZ39 acted as the core strain, which played a crucial role in the bioreactor. The mechanism of enhanced denitrification was attributed to minor F- stress and bioaugmentation technology. This study highlighted the superiorities of SFFMs and MICP combined remediation and documented a promising option for F-, NO3-, and Ca2+ removal.

Chitosan and carboxymethyl chitosan mimic biomineralization and promote microbially induced calcium precipitation.

This research aimed to evaluate chitosan (CTS) and carboxymethyl chitosan (CMCS) as polysaccharides that could mimic the role of bacterial extracellular polymeric substance (EPS) in the biomineralization process through bionic experiments. The introduction of COOH resulted in higher calcium precipitation efficiency of CMCS (65.07%) than CTS (55.66%). CaCO3 nucleation on the surface of CTS and CMCS was triggered through the binding of Ca2+ to NH2, OH, COOH and NHCOCH3 groups. Moreover, the experiment of polysaccharides mediated biomineralization was conducted. The maximum calcium precipitation efficiency reached 96.07% with the addition of 0.15% CMCS. Combining the characterization results, the synergetic mineralization mechanisms between polysaccharides and bacteria were proposed. Among them, bacterial metabolic by-products (alkalinity), active groups and adhesion of polysaccharides played a significant role. This work provides a reference for further understanding of the biomineralization mechanism, and gives a new insight into the intensified strategies of MICP technology.

Influence of advanced life support response time on out-of-hospital cardiac arrest patient outcomes in Taipei.

BACKGROUND: The association between out-of-hospital cardiac arrest patient survival and advanced life support response time remained controversial. We aimed to test the hypothesis that for adult, non-traumatic, out-of-hospital cardiac arrest patients, a shorter advanced life support response time is associated with a better chance of survival. We analyzed Utstein-based registry data on adult, non-traumatic, out-of-hospital cardiac arrest patients in Taipei from 2011 to 2015. METHODS: Patients without complete data, witnessed by emergency medical technicians, or with response times of ≥ 15 minutes, were excluded. We used logistic regression with an exposure of advanced life support response time. Primary and secondary outcomes were survival to hospital discharge and favorable neurological outcomes (cerebral performance category ≤ 2), respectively. Subgroup analyses were based on presenting rhythms of out-of-hospital cardiac arrest, bystander cardiopulmonary resuscitation, and witness status. RESULTS: A total of 4,278 cases were included in the final analysis. The median advanced life support response time was 9 minutes. For every minute delayed in advanced life support response time, the chance of survival to hospital discharge would reduce by 7% and chance of favorable neurological outcome by 9%. Subgroup analysis showed that a longer advanced life support response time was negatively associated with the chance of survival to hospital discharge among out-of-hospital cardiac arrest patients with shockable rhythm and pulse electrical activity groups. CONCLUSIONS: In non-traumatic, adult, out-of-hospital cardiac arrest patients in Taipei, a longer advanced life support response time was associated with declining odds of survival to hospital discharge and favorable neurologic outcomes, especially in patients presenting with shockable rhythm and pulse electrical activity.

Effect of Placement of a Supraglottic Airway Device vs Endotracheal Intubation on Return of Spontaneous Circulation in Adults With Out-of-Hospital Cardiac Arrest in Taipei, Taiwan: A Cluster Randomized Clinical Trial.

Importance: Prehospital advanced airway management with either initial endotracheal intubation (ETI) or initial supraglottic airway (SGA) insertion in patients with out-of-hospital cardiac arrest (OHCA) remains controversial. Objective: To compare the effectiveness of ETI and SGA in patients with nontraumatic OHCA. Design, Setting, and Participants: The Supraglottic Airway Device vs Endotracheal intubation (SAVE) trial was a multicenter cluster randomized clinical trial conducted in Taipei City, Taiwan. Individuals aged 20 years or older who experienced nontraumatic OHCA requiring advanced airway management and were treated by participating emergency medical service agencies were enrolled from November 11, 2016, to December 31, 2019. The final day of follow-up was February 19, 2020. Interventions: Four advanced life support ambulance teams were divided into 2 randomization clusters, with each cluster assigned to either ETI or SGA in a biweekly period. Main Outcomes and Measures: The primary outcome of the SAVE trial was sustained return of spontaneous circulation (ROSC) (≥2 hours) after resuscitation. Secondary outcomes included prehospital ROSC, survival to hospital discharge, and favorable neurologic outcome, defined as a cerebral performance category score less than or equal to 2. Prespecified subgroups and the association between time to advanced airways were explored. Per protocol and intention-to-treat analysis were performed. Results: A total of 936 patients (517 in the ETI group and 419 in the SGA group) were included in the primary analysis (median age, 77 [IQR, 62-85] years; 569 men [60.8%]). The first-attempt airway success rates were 77% with ETI (n = 413) and 83% with SGA (n = 360). Sustained ROSC was 26.9% (n = 139) in the ETI group vs 25.8% (n = 108) in the SGA group. The odds ratio of sustained ROSC was 1.02 (95% CI, 0.98-1.06) in the ETI group vs SGA group. The odds ratio of ETA vs SGA was 1.04 (95% CI, 1.02-1.07) for prehospital ROSC, 1.00 (95% CI, 0.94-1.06) for survival to hospital discharge, and 0.99 (95% CI, 0.94-1.03) for cerebral performance category scores less than or equal to 2. Conclusions and Relevance: In this randomized clinical trial, among patients with OHCA, initial airway management with ETI did not result in a favorable outcome of sustained ROSC compared with SGA device insertion. Trial Registration: ClinicalTrials.gov Identifier: NCT02967952.

Microbial induced calcium precipitation based anaerobic immobilized biofilm reactor for fluoride, calcium, and nitrate removal from groundwater.

In this study, the anaerobic quartz sand fixed biofilm reactor containing Cupriavidus sp. W12 was established to simultaneously remove calcium (Ca2+), fluoride (F-) and nitrate (NO3-N) from groundwater. After 84 days of continuous operation, the optimum operating parameters and defluoridation mechanism were explored, and the microbial community structure under different pH environments were compared and analyzed. Under the optimal operation conditions (HRT of 6 h, initial Ca2+ concentration of 180 mg L-1, and pH of 7.0), the removal efficiencies of Ca2+, F-, and NO3-N were 58.97%, 91.93%, and 100%, respectively. Gas chromatography (GC) results indicate that N2 is the main gas produced by the bioreactor. Three-dimension excitation emission matrix fluorescence spectroscopy (3D-EEM) showed that extracellular polymers (EPS) are produced during bacterial growth and metabolism. The results of Scanning electron microscopy-energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD), and Fourier transform infrared spectrometer (FTIR) demonstrated that the defluoridation mechanism is attributed to the synergetic effects of ion exchange, co-precipitation, and chemisorption. The comparative analysis of the microbial community structure under different pH conditions show that Cupriavidus is the dominant bacteria in the bioreactor throughout the experiment, and it shows a prominent advantage at pH of 7.0. This research provides an application foundation for anaerobic microbial induced calcium precipitation (MICP) bioremediation of Ca2+, F-, and NO3-N from groundwater.

Outcomes of out-of-hospital cardiac arrests after a decade of system-wide initiatives optimising community chain of survival in Taipei city.

OBJECTIVE: A strengthened chain of survival benefits patient outcomes after out-of-hospital cardiac arrest (OHCA).2 Over the past decade, the Taipei Fire Department (TFD) has continuously implemented system-wide initiatives on this issue.We hypothesised that for adult, non-trauma OHCA patients, the bundle of these system-wide initiatives are associated with better outcomes. METHODS: We conducted a registry-based, retrospective study to examine the association between consecutive system-level initiatives and OHCA survival on a two-yearly basis using trend analysis and multivariable logistic regression. The primary outcome was survival to hospital discharge (STHD) and favourable neurological status. RESULTS: We analysed 18,076 cases from 2008 to 2017. The numbers of two-yearly cases of OHCA with resuscitation attempts from 2008 to 2017 were 3,576, 3,456, 3,822, 3,811, and 3,411. There was a significant trend of improved STHD (Two-fold) and favourable neurological outcome (Six-fold) over the past decade. Similar trends were observed in the shockable and non-shockable groups. Considering the first 2 years as baseline, the odds of STHD and favourable neurological status in the end of the initiatives increased significantly after adjusting for universally recognised predictors for OHCA survival. CONCLUSION: For non-trauma adult OHCA in Taipei, continuous, multifaceted system-wide initiatives on the community chain of survival were associated with improved odds of STHD and favourable neurologic outcomes.

Synergistic removal of fluoride from groundwater by seed crystals and bacteria based on microbially induced calcium precipitation.

A new hypothesis that seed crystals (SC) and bacteria based on microbially induced calcium precipitation (MICP) synergistically remove fluoride (F-) from groundwater was proposed, with a focus on evaluating the defluoridation potential of this method and revealing its F- removal mechanism. The crucial conditions were optimized to reduce preparation and operation costs. SC furnished more available binding sites due to the existence of bacteria, and the reuse experiments showed that the defluoridation efficiency of SC still remained a high level after 14 cycles (70.10%), with a residual F- concentration of 0.96 mg L-1. The SEM-EDS, FTIR and XRD analyses indicated the predominant F- removal mechanism of SC could be ascribed to the chemisorption, ion exchange, and co-precipitation. Moreover, ion exchange and co-precipitation (PO43- involvement) were validated more contributive than chemisorption (CaCO3 and CaSO4 involvement). As a feasible, reusable, and eco-friendly technique, SC suggests promising applications in the treatment of fluoride-contaminated groundwater.

Microbially induced calcium precipitation based simultaneous removal of fluoride, nitrate, and calcium by Pseudomonas sp. WZ39: Mechanisms and nucleation pathways.

A simultaneous denitrifying and mineralizing bacterium, Pseudomonas sp. WZ39 was isolated for fluoride (F-), nitrate (NO3--N), and calcium (Ca2+) removal. Strain WZ39 exhibited a remarkable defluoridation efficiency of 87.49% under a pH of 6.90, F- and Ca2+ concentration of 1.99 and 201.88 mg L-1, respectively. EEM, SEM-EDS, XRD, and FTIR analyses elucidated the chemical adsorption and co-precipitation with calcium salt contributed to the removal of F-. The mechanisms of biomineralization were also investigated by determining the role of bound and unbound extracellular polymeric substances (EPS), cell wall, and calcium channel in nucleation. The results showed that bacteria can promote nucleation on the templates of cell walls or EPS through the electrostatic effect. The presence of the calcium channel blocker inhibited the transport of intracellular Ca2+ to the extracellular environment. The outcome of the present research can provide a theoretical basis for the understanding of MICP phenomenon and the efficient treatment of F- containing groundwater.

Batch fluidized bed reactor based modified biosynthetic crystals: Optimization of adsorptive properties and application in fluoride removal from groundwater.

A batch fluidized bed reactor (BFBR) with modified biosynthetic crystals (MBC), derived from Pseudomonas sp. HXF1, was investigated for the treatment of the groundwater containing fluoride (F-). Impacts of different hydraulic retention time (HRT), pH, and initial F- concentration on F- removal were examined and the maximum defluorination efficiency was recorded as 95.20%. Moreover, recycling experiments were performed to evaluate the stability of repeated use. BFBR/MBC system showed a long-term effective treatment outcome with low fluctuation in the concentrations of residual Ca2+ and F-. The formed precipitates were characterized by SEM, XPS, XRD, and FTIR. The defluorination mechanisms of BFBR/MBC system were defined as the chemisorption and induced crystallization of Ca5(PO4)3F on the MBC surface. As a feasible, economical, and environment-friendly technique, the method has a long-term value, which suggests promising applications in F- removal and resourceful treatment.