Simultaneous ammonium and phosphate removal with Mg-loaded chitosan carbonized microsphere: Influencing factors and removal mechanism.

A novel Mg-loaded chitosan carbonized microsphere (MCCM) was prepared for simultaneous adsorption of ammonium and phosphate in this study, through the investigation of preparation procedures, addition ratio, and preparation temperature. Pollutants removals by MCCM were more acceptable with 64.71% for ammonium and 99.26% for phosphorus, compared with chitosan carbonized microspheres (CCM), Mg-loaded chitosan hydrogel beads (MCH) and MgCl2·6H2O. Addition ratio of 0.6:1 (mchitosan: mMgCl2) and preparation temperature of 400 °C in MCCM preparation were responsible for pollutant removal and yield. The effect analysis of MCCM dosage, solution pH, pollutant concentration, adsorption mode and coexisting ions on the removal for both ammonium and phosphate indicated that pollutants removals were increased with increasing MCCM dosages, and achieved the peak at pH 8.5, but presented to be stable with Na+, K+, Ca2+, Cl-, NO3-, CO32- and SO42-, except for Fe3+.Adsorption mechanisms discussion implied that simultaneous ammonium and phosphate removal with MCCM was attributed to struvite precipitation, ion exchange, hydrogen bonding, electrostatic attraction and Mg-P complexation, suggesting that MCCM presents a new way for simultaneous concentrated ammonium and phosphate removal in wastewater treatment.

Outflow risks of antibiotic-resistant bacteria in stormwater bioretention cells: understanding roles of adsorption and transmission.

In this study, lab-scale bioretention cells were designed for the investigation of antibiotic-resistant bacteria (ARB) outflow profiles at different depths, effects of adsorption and transmission, as well as modelling evaluation of ARB outflow risks using the common decay models (e.g., first-order decay models). ARB outflow was first found in the upper layers (after 100 days of the operation) with the lowest transmission frequencies of antibiotic resistance. Although the adsorption of ARB onto the substrate and its surface biofilms was effective with the maximum amount of ARB adsorbed (Qmax) reaching 108 CFU/g of the substrate and 107 CFU/g of biofilms, ARB outflow was detected in the bottom outlets after over 4 months of operation, reflecting that there was still a risk of antibiotic resistance through the treatment of bioretention cells. ARB outflow for both upper and middle outlets could be well described by third-order polynomial equations with correlation coefficients 0.9067 (p = 0.0002) and 0.9780 (p < 0.0001), respectively, where there were both positive and negative relationships between outflow ARB and inflow ARB, confirming the combined action of mechanisms blocking ARB outflow (e.g., substrate adsorption) and promoting ARB outflow (like transmission). These suggested two potential controlling approaches for ARB outflow from stormwater bioretention cells.

O- and F-doped porous carbon bifunctional catalyst derived from polyvinylidene fluoride for sulfamerazine removal in the metal-free electro-Fenton process.

Heteroatom-doped carbon materials can effectively activate H2O2 into •OH during the metal-free electro-Fenton (EF) process. However, information on bifunctional catalysts for the simultaneous generation and activation of H2O2 is scarce. In this study, O- and F-doped porous carbon cathode materials (PPCs) were prepared by the direct carbonization of polyvinylidene fluoride (PVDF) for sulfamerazine (SMR) removal in a metal-free EF process. The porous structure and chemical composition of the PPCs were regulated by the carbonization temperature. PPC-6 (carbonized at 600 °C) exhibited optimal electrocatalytic performance in terms of electrochemical H2O2 generation and activation owing to its high specific surface area, mesoporous structure, and optimum fractions of doped O and F. Excellent performance of the 2e- oxygen reduction reaction was found with an H2O2 selectivity of 93.5% and an average electron transfer number of 2.13. An H2O2 accumulative concentration of 103.9 mg/L and an SMR removal efficiency of 90.1% were achieved during the metal-free EF process. PPC-6 was able to stably remove SMR over five consecutive cycles, retaining 92.6% of its original performance. Quantitative structure-activity relationship analysis revealed that doped oxygen functional groups contributed substantially to H2O2 generation, and semi-ionic C-F bonds with high electronegativity were the cause of the activation of H2O2 to •OH. These findings suggest that the PVDF-derived carbonaceous catalysts are feasible and desirable for metal-free EF processes.

Tannic acid-Fe complex derivative-modified electrode with pH regulating function for environmental remediation by electro-Fenton process.

A heterogeneous electro-Fenton (hetero-EF) system can effectively broaden the applicable pH range, although the decreased electrogeneration efficiency of H2O2 at elevated pH (especially neutral conditions) is unfavorable for the efficient removal of organic pollutants. Herein, a tannic acid-Fe complex derivative-modified carbon felt (TFD@CF) cathode was prepared for hetero-EF treatment of organic pollutants over a wide pH range. Interestingly, the as-prepared hetero-EF cathode could act as a pH regulator that acidified the solution over a wide pH range. As expected, the TFD@CF cathode exhibited excellent hetero-EF activity for the removal of diverse organic pollutants (such as methyl orange, methylene blue, sulfamerazine, bisphenol A and 2,4-dichlorophenoxyacetic acid) at neutral and even alkaline pH (removal efficiency >90 %). A total of 2.98 kWh kg-1 COD-1 with 83.2 % COD removal could be achieved by the TFD@CF cathode for the treatment of actual textile dyeing secondary wastewater. Electrochemical characterizations proved that the TFD@CF cathode had excellent electrochemical properties with improved electron transfer ability and a well-pronounced Fe(III) electroreductive response. Meanwhile, more acidic groups were newly generated during the electrochemical reaction (an increase of 30.1 %), thus dissociating more H+ into solution. The identification of reactive oxygen species suggested that OH and 1O2 could be responsible for the removal of organic pollutants in the TFD@CF EF system. These interesting findings may provide new insights into the design of multifunctional hetero-EF cathodes for the removal of refractory organic pollutants.

Inactivation of antibiotic resistant bacteria from stormwater runoff using UVA/LED and its potential risks.

Recently, increasing attention has been paid to antibiotic resistance in stormwater runoff. However, there is no available literature about the control of antibiotic resistant bacteria (ARB) through 365 nm ultraviolet light-emitting diode (UVA/LED). In this study, batch experiments were conducted to investigate ARB inactivation kinetics, effects of light intensity and water matrix (including suspended solid (SS) concentration, initial pH and bacteria concentration), and potential transmission risks after UVA/LED irradiation. Results showed that ARB inactivation efficiencies reached 6.31 log reduction at 8 mW/cm2 (86 J/cm2) of UVA/LED for 180 min. ARB inactivation efficiencies increased with the increase of light intensity, and showed a linear relationship. ARB inactivation decreased with increasing SS levels, and the largest inactivation efficiencies was 3.56 log reduction at 50 mg/L of SS. Initial pH had slight effect on ARB inactivation through UVA/LED irradiation. A low initial bacteria concentration (105 CFU/mL) was not necessarily associated with good ARB inactivation (3.59 log reduction). After UVA/LED irradiation, ARB was hardly detected during 12 hr of dark repair, and the transfer frequency of kanamycin resistance gene was increased to 5.43 × 10-4. These suggested that the application of UVA/LED to inactivate ARB in stormwater runoff was feasible and desirable in this study.

Cerebello-cerebral connectivity in idiopathic generalized epilepsy.

PURPOSE: The present study aims to investigate structural and functional connectivity (SC and FC) in cerebello-cerebral circuit in idiopathic generalized epilepsy (IGE). METHODS: Diffusion tensor imaging and resting-state imaging data were collected from 57 patients with IGE and 66 controls in the present study. First, we performed bidirectional probabilistic fiber tracking between cerebellum and cerebral cortex, consisting of cerebellar efferent and afferent fibers. Then, strength of structural connectivity (SCS), fractional anisotropy (FA), mean diffusivity (MD), and radial diffusivity (RD) were extracted and compared between groups. Finally, cerebellar FC with cerebral cortex was evaluated with seeding at dentate nucleus. Between-group comparisons were performed using t tests with a significant level setting at p < 0.05 with threshold-free cluster enhancement correction. RESULTS: The patients with IGE showed decreased SCS in cerebellar efferent fibers to sensorimotor cortex in anterior corona radiate and increased SCS in efferent fibers to occipital cortex in posterior corona radiata. The SCS in cerebellar afferent fibers in corticospinal tract from frontal and in retrolenticular part of the internal capsule from occipital cortices were increased in IGE, and SCS in afferent fibers in posterior limb of internal capsule from parietal cortex was decreased. Decreased FA and increased MD and RD were observed in cerebello-cerebral tracts. Besides, decreased cerebellar FC with putamen and motor cortex was observed in IGE. CONCLUSION: The patients with IGE demonstrated distinct alterations in efferent and afferent pathways between cerebellum and different cerebral cortices, which might be the pathological anatomical basis for cerebellar modulation effect on epileptic activities and contribute to motor deficits. KEY POINTS: • IGE showed decreased SCS in cerebellar efferent fibers to the sensorimotor cortex and increased SCS in efferent fibers to the occipital cortex. • Patients demonstrated increased SCS in cerebellar afferent fibers from the frontal and the occipital cortex and decreased SCS in afferent fibers from parietal cortex. • Decreased FC between motor-related regions and dentate nucleus was observed in IGE.

The role of water matrix on antibiotic resistance genes transmission in substrate layer from stormwater bioretention cells.

Recently, extensive attention has been paid to antibiotic resistance genes (ARGs) transmission. However, little available literature could be found about ARGs transmission in stormwater bioretention cells, especially the role of water matrix on ARGs transmission. Batch experiments were conducted to investigate target ARGs (blaTEM, tetR and aphA) transmission behaviors in substrate layer from stormwater bioretention cells under different water matrices, including nutrient elements (e.g., carbon, nitrogen and phosphorus), water environmental conditions (dissolved oxygen (DO), pH and salinity, etc.) and pollution factors (like heavy metals, antibiotics and disinfectants), showing that ARGs conjugation frequency increased sharply with the enhancement of water matrices (expect DO and pH), while there were obvious increasing tendencies for all ARGs transformation frequencies under only the pollution factor. The correlation between dominant bacteria and ARGs transmission implied that conjugation and transformation of ARGs were mainly determined by Firmicutes, Bacteroidota, Latescibacterota, Chloroflexi and Cyanobacteria at the phylum level, and by Sphingomonas, Ensifer, IMCC26256, Rubellimicrobium, Saccharimonadales, Vicinamibacteraceae, Nocardioides, JG30-KF-CM66 at the genus level. The mentioned dominant bacteria were responsible for intracellular reactive oxygen species (ROS) and cell membrane permeability (CMP) in the substrate layer, where the amplification of intracellular ROS variation were the largest with 144 and 147 % under the condition of TP and salinity, respectively, and the one of CMP variation were the highest more than 165 % under various pollution factors. Furthermore, both increasing DO and reducing salinity could be potential approaches for the inhibition of ARGs transmission in bioretention cells taking into account the simultaneous removal of conventional pollutants.

Dissolved oxygen facilitates efficiency of chlorine disinfection for antibiotic resistance.

Controlling the dissemination of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) is a global concern. While commonly used chlorine disinfectants can damage or even kill ARB, dissolved oxygen (DO) may affect the formation of reactive chlorine species. This leads to the hypothesis that DO may play roles in mediating the effectiveness of chlorine disinfection for antibiotic resistance. To this end, this study investigated the impacts of DO on the efficiency of chlorine disinfection for antibiotic resistance. The results revealed that DO could increase the inactivation efficiency of ARB under chloramine and free chlorine exposure at practically relevant concentrations. Reactive species induced by DO, including H2O2, O2-, and OH, inactivated ARB strains by triggering oxidative stress response and cell membrane damage. In addition, the removal efficiency of extracellular ARGs (i.e. tetA and blaTEM) was enhanced with increasing dosage of free chlorine or chloramine under aerobic conditions. DO facilitated the fragmentation of plasmids, contributing to the degradation of extracellular ARGs under exposure to chlorine disinfectants. The findings suggested that DO facilitates disinfection efficiency for antibiotic resistance in water treatment systems.

Stormwater runoff treatment through electrocoagulation: antibiotic resistant bacteria removal and its transmission risks.

Recently, increasing attention has been paid to antibiotic resistant bacteria (ARB) in stormwater runoff. However, there were little data on ARB removal through electrocoagulation (EC) treatment. In this study, batch experiments were conducted to investigate key designs for ARB removal, role of SS, effects of water matrix, and potential risks after EC treatment under the pre-determined conditions. EC treatment with 5 mA/cm2 of current density and 4 cm of inter-electrode distance was optimal with the highest ARB removal (3.04 log reduction for 30 min). The presence of SS significantly improved ARB removal during EC treatment, where ARB removal increased with the increase of SS levels when SS less than 300 mg/L. Large ARB removal was found under particles with size lower than 150 µm with low contribution (less than 10%) of the settlement without EC treatment, implying that the enhancement of ARB adsorption onto small particles could be one of the reasonable approaches for ARB removal through EC treatment. ARB removal increased firstly and then decreased with the increase of pH, while had proportional relationship with conductivity. After the optimal condition, there were weak conjugation transfer but high transformation frequency (5.5 × 10-2 for blaTEM) for target antibiotic resistance genes (ARGs), indicating that there could be still a risk of antibiotic resistance transformation after EC treatment. These suggested that the combination of EC and other technologies (like electrochemical disinfection) should be potential ways to control antibiotic resistance transmission through stormwater runoff.

Sustainable phosphorus adsorption and recovery from aqueous solution by a novel recyclable Ca-PAC-CTS.

Phosphorus removal has been explored for a long time, however sustainable phosphorus adsorption and recovery with adsorbents recycling is rarely reported. This work proposes a sustainable phosphorus recycling route with calcium-modified powdered activated carbon with chitosan (Ca-PAC-CTS). The morphology, functional groups and crystal structure of Ca-PAC-CTS were characterized. The maximum phosphorus adsorption capacity was 16.73 mg/g Ca-PAC-CTS with Langmuir model at 298 K. Stable phosphorus sorption on Ca-PAC-CTS could be observed at the large range of pH (4- 10) when coexisting with NO3-, SO42-, Cl- and F-, except HCO3-. 98.95 % The recovery of adsorbed phosphorus could get to 98.95 % using 0.05 M sulfuric acid solution, and the phosphate adsorption efficiency through Ca-PAC-CTS remained to be more than 80 % after five adsorption-desorption cycles, suggesting that Ca-PAC-CTS was one of the promising adsorbents for sustainable removal and recovery of phosphorus in aqueous solution.

Application of electrochemical oxidation for the enhancement of antibiotic resistant bacteria removal in stormwater bioretention cells.

Recently, increasing attention has been paid to the removal of antibiotic resistant bacteria (ARB) during electrochemical advanced oxidation processes. However, there is still no available literature about the application of electrochemical oxidation (EO) to enhance ARB removal in stormwater bioretention cells. Batch experiments were conducted to investigate target ARB (E. coli K-12 carrying blaTEM, tetR and aphA) removals in bioretention cells with different current densities and ratios of air to water (A/W). ARB removals for bioretention cells with 17.6 µA/m2 of current density and 24:1 of A/W ratio was the largest with 5.28 log reduction, which was obviously higher than the one (3.68 log reduction) in the control (without EO). H2O2 production could be responsible for ARB removals in the used bioretention cells, where H2O2 levels increased at first and then decreased with the increase of current densities and A/W ratios. The evaluation for the application of EO implied that the highest antibiotic resistance (AR) conjugation frequency (3.8 × 10-3) at 3.5 µA/m2 of current density and 48:1 of A/W ratios was 124.5 % of the one in the control, while the largest AR transformation frequencies at 17.6 µA/m2 of current density and 48:1 of A/W ratios was 366.9 % (tetR) and 216.2 % (aphA) of the corresponding in the control, and there were still stable for both dominant microflora and metabolic activities in bioretention cells with electricity and aeration, suggesting that EO could be promising for the enhancement of ARB removals in bioretention cells.

Hydrothermal carbonization coupling with liquid dimethyl ether extraction pretreatment of sewage sludge: Hydrochar performance improvement and low-nitrogen biocrude production.

Hydrothermal carbonization of sewage sludge converts waste into hydrochar; however, the complex organic composition of feedstock limits the product value. A novel process that combines liquid dimethyl ether extraction and hydrothermal carbonization (DE-HTC) was proposed for improving the product value by simultaneously producing biocrude/hydrochar and improving feedstock suitability for thermochemical conversion. Biocrude and hydrochar with a product yield of 2.62% and 55.83% were produced via DE-HTC, respectively. The hydrochar yield increased by 12.65%-29.90% compared to traditional single-step hydrothermal carbonization. The hydrochar energy densification was decreased by 1.16%-10.28%, while hydrochar's energy yield increased by 47%-66%, and it had a more prominent porous structure. By avoiding the decomposition of proteins during thermochemical conversion, the nitrogen content of the biocrude obtained via DE-HTC was only 0.38%. The biocrude was also further qualitatively analyzed. This study provides insights into the efficacy of a novel hydrothermal method with distinct product value advantages over direct hydrothermal carbonization.

Associating Multimodal Neuroimaging Abnormalities With the Transcriptome and Neurotransmitter Signatures in Schizophrenia.

BACKGROUND AND HYPOTHESIS: Schizophrenia is a multidimensional disease. This study proposes a new research framework that combines multimodal meta-analysis and genetic/molecular architecture to solve the consistency in neuroimaging biomarkers of schizophrenia and whether these link to molecular genetics. STUDY DESIGN: We systematically searched Web of Science, PubMed, and BrainMap for the amplitude of low-frequency fluctuations (ALFF) or fractional ALFF, regional homogeneity, regional cerebral blood flow, and voxel-based morphometry analysis studies investigating schizophrenia. The pooled-modality, single-modality, and illness duration-dependent meta-analyses were performed using the activation likelihood estimation algorithm. Subsequently, Spearman correlation and partial least squares regression analyses were conducted to assess the relationship between identified reliable convergent patterns of multimodality and neurotransmitter/transcriptome, using prior molecular imaging and brain-wide gene expression. STUDY RESULTS: In total, 203 experiments comprising 10 613 patients and 10 461 healthy controls were included. Multimodal meta-analysis showed that brain regions of significant convergence in schizophrenia were mainly distributed in the frontotemporal cortex, anterior cingulate cortex, insula, thalamus, striatum, and hippocampus. Interestingly, the analyses of illness-duration subgroups identified aberrant functional and structural evolutionary patterns: Lines from the striatum to the cortical core networks to extensive cortical and subcortical regions. Subsequently, we found that these robust multimodal neuroimaging abnormalities were associated with multiple neurobiological abnormalities, such as dopaminergic, glutamatergic, serotonergic, and GABAergic systems. CONCLUSIONS: This work links transcriptome/neurotransmitters with reliable structural and functional signatures of brain abnormalities underlying disease effects in schizophrenia, which provides novel insight into the understanding of schizophrenia pathophysiology and targeted treatments.

Column studies to determine mercury settling in road runoff.

A study was performed using a settling column to remove mercury (Hg) from road runoff. The emphasis was placed on the relationship between Hg removal and critical settling velocities, as well as the distribution of total suspended solids (TSS). The impact of rainfall characteristics and temperature on Hg removal was also discussed. Results indicated that Hg removal was significant within the initial 30 min of the settling process. The Hg removal rate increased with the decrease of critical settling velocity, and this trend became gradually significant, which could be used as an important reference for the optimization of sedimentation basin design. Hg removal at different settling times was significantly related to initial distribution of TSS. The impact of rainfall intensity on Hg removal was greater than other parameters of precipitation features, followed by rainfall. In addition, Hg removal was moderately related to temperature. The effect of antecedent dry periods on Hg removal was restricted by rainfall and rainfall intensity.

Distribution of typical antibiotic resistance genes in underlying surface sediments from urban commercial public squares and their potential hosts.

Increasing attention has been paid to antibiotic resistance genes (ARGs) in environments. However, no available literature could be found on ARGs contamination in urban underlying surface sediments. In this study, sediments from commercial public squares around Nanjing (China) were selected for the investigation of target ARGs distribution, showing that intracellular ARGs (iARGs) in particles were the dominant with their relative abundances in descending order of 4.82 × 10-2 copies/16S rRNA (<0.063 mm), 4.18 × 10-2 copies/16S rRNA (0.063-0.125 mm), 3.70 × 10-2 copies/16S rRNA (0.25-0.5 mm), 3.44 × 10-2 copies/16S rRNA (0.5-1 mm), 3.20 × 10-2 copies/16S rRNA (0.125-0.25 mm) and 9.53 × 10-3 copies/16S rRNA (1-2 mm), which was different with that of extracellular ARGs (eARGs). The influence of street sweeping on ARGs levels indicated that the species and relative abundances for both iARGs and eARGs in sediments from different sites were not consistent with the corresponding population densities. The correlation between ARGs and dominant bacterial communities implied that both Firmicutes and Bacteroidetes were positively correlated with ARGs (P < 0.01). The role of solar UV disinfection demonstrated that UV irradiation could inactivate antibiotic resistance bacteria (ARB) slightly with 0.5-1.0 log reduction, implying a considerable risk of ARB after solar irradiation. Our results suggested that it would need the more effective sweeping modes for the cleaning of small particles (<0.25 mm) and the higher disinfection to ARGs potential hosts (like Firmicutes and Blastocatella).

Antibiotic resistant bacteria inactivation through metal-free electrochemical disinfection with carbon catalysts and its potential risks.

Recently, increasing attention has been paid to the inactivation of antibiotic resistant bacteria (ARB) during the electrochemical disinfection. However, no available information could be found on ARB inactivation in water during metal-free electrochemical disinfection. In this study, polyvinylidene fluoride (PVDF)-based carbon catalyst (PPC) was chosen as working electrode. Batch experiments were conducted to investigate key design for ARB inactivation, effects of water matrix and potential risks after the disinfection under the pre-determined conditions. The disinfection with current density at 2.25 mA/cm2 and Air/Water ratio of 10:1 was optimal with the largest ARB inactivation (5.0 log reduction for 40 min), which was in line with the profile and yield of hydrogen peroxide (H2O2) during the disinfection. Effects of water matrix analysis implied that ARB inactivation efficiencies during the disinfection in acidic solutions were better than the one in alkaline solutions, which could be due to rich CC levels on surface of PPC cathode. After the optimal disinfection, ARB counts increased slightly at the first 2 h and then tended to disappear, and there were no conjugation transfer and little transformation for target antibiotic resistance genes, indicating that potential risks could be blocked after the disinfection for 40 min. Furthermore, intermittent flow was more effective in inactivating ARB compared with continuous flow. These suggested that the application of metal-free electrochemical disinfection with PPC to inactivate ARB in water was feasible and desirable in this study.

Diversity and distribution of antibiotic resistance genes associated with road sediments transported in urban stormwater runoff.

Recently, increasing attention has been paid to antibiotic resistance genes (ARGs) in urban stormwater runoff. However, there were little data on the diversity and distribution of ARGs associated with road sediments transported in runoff. The investigation of ARGs diversity showed that sulfonamide resistance genes (sul2 and sul3) occupied 61.7%-82.3% of total ARGs in runoff. The analysis of ARGs distribution in particulate matter (PM) implied that both tetQ and trbC existed mainly in PM with size of 150-300 µm, but other ARGs and mobile genetic elements (MGEs) were dominant in PM with size <75 µm. The discussion of potential hosts indicated that target genes (ermF, blaOXA1/blaOXA30, ermC, qnrA, sul2, tnpA-01, intI2, tetW, intI1, sul3, trbC) had the strongest subordinate relationship with Proteobacteria at phylum level and Enterobacter at genus level. The effect evaluation of ARGs distribution suggested that 13 kinds of ARGs were positively correlated with Pr/PS and Zeta potential, resulting in the more ARGs in PM with smaller size (<75 µm).

Antibiotic resistance genes removals in stormwater bioretention cells with three kinds of environmental conditions.

Recently, increasing attention has been paid to antibiotic resistance genes (ARGs) in stormwater runoff. However, there is still no available literature about ARGs removals through stormwater bioretention cells. Batch experiments were conducted to investigate target ARGs (blaTEM, tetR and aphA) removals under three environmental conditions, including substrate (weight ratios of sand to soil), hydraulic loading rate (HLR) and submerged area depth. The target ARGs removals were the largest (more than 5 log in the bottom outlets) in bioretention cells with 8:2 ratio of sand to soil, HLR 0.044 cm3/cm2/min and 150 mm of submerged area depth. The proportion for both iARGs and eARGs had little effect on target ARGs removals (expect extracellular blaTEM), although distributions of target ARGs were different in substrate layers. Adsorption behavior tests indicated that both kinetics and isotherms of target ARGs adsorption by biofilms were more suitable to explain their best removals for bioretention cells with 8:2 ratio of sand to soil than that by substrate. At phylum and genus levels, there were respectively 6 dominant microflora related significantly to target ARGs levels, and their relationships changed obviously under different environmental conditions, suggesting that regulating the dominant microflora (like Verrucomicrobia and Actinobacteria) could be feasible to change ARGs removals.

Leaching risks of antibiotic resistance genes in urban underlying surface sediments during the simulated stormwater runoff and its controls.

Recently, increasing attention has been paid to antibiotic resistance genes (ARGs) in urban stormwater runoff. However, no available literature could be found on ARGs leaching from urban underlying surface sediments during stormwater runoff. In this study, surface sediments from commercial public squares around Nanjing (China) was selected for the investigation of target ARGs leaching kinetics, showing that absolute abundances of target ARGs desorption reached at the equilibrium during leaching time of 120-240min with all of the desorption efficiencies about 30%, indicating that there would be low proportion of leaching ARGs in the total ARGs migrating with runoff during rainfall events. Five target ARGs leaching including intI1 (clinic), strA, strB, tetM and tetX can be better described by the pseudo-second-order equation, while qacEdelta1 leaching can be better described by the pseudo-first-order equation, and the leaching for both sul1 and sul2 can be well described by the pseudo-first-order and pseudo-second-order equations. The effects of environmental factors including S/L ratios, pH values and water temperatures indicated that leaching efficiencies of target ARGs enhanced significantly with the increase of S/L ratios and water temperatures, but decreased with the increase of pH values. The transmission experiments after the simulated solar irradiation and heat implied that both large solar UV irradiation (30W/m2) and high temperature (40℃) were conducive to conjugation and transformation frequencies of ARGs. Furthermore, both high Cao and medium PAM levels could be effective for blocking ARGs transmission in the leachate from underlying surface sediments.

Increase of antibiotic resistance genes via horizontal transfer in single- and two-chamber microbial electrolysis cells.

Microbial electrolysis cells (MECs) have been applied for antibiotic degradation but simultaneously induced antibiotic resistance genes (ARGs), thus representing a risk to disseminate antibiotic resistance. However, few studies were on the potential and risk of ARGs transmission in the MECs. This work assessed conjugative transfer of ARGs under three tested conditions (voltages, cell concentration, and donor/recipient ratio) in both single- and two-chamber MECs. The results indicated that voltages (> 0.9 V) facilitated the horizontal frequency of ARGs in the single-chamber MECs and anode chamber of two-chamber MECs. The donor cell number (donor/recipient ratio was 2:1) increased the transfer frequency of ARGs. Furthermore, voltages ranged from 0.9 to 2.5 V increased reactive oxygen species (ROS) production and cell membrane permeability in MECs. These findings offer new insights into the roles of ARG transfer under different applied voltages in the MECs, which should not be ignored for horizontal transfer of antibiotic resistance.