Trifunctional Cu-Mesh/Cu_(2)O@FeO Nanoarrays for Highly Efficient Degradation of Antibiotic, Inactivation of Antibiotic-Resistant Bacteria, and Damage of Antibiotics Resistance Genes

Trifunctional Cu-mesh/Cu_(2)O@FeO nanoarrays heterostructure is designed and fabricated by integrating CuCu_(2)O@FeO nanoarrays onto Cu-mesh(CM)via an in situ growth and phase transformation process.It is successfully applied to efficiently mitigate the antibiotic pollution,including degradation of antibiotics,inactivation of antibiotic-resistant bacteria(ARB),and damage of antibiotics resistance genes(ARGs).Under visible-light irradiation,CM/CuCu_(2)O@FeO nanoarrays exhibit a superior degradation efficiency on antibiotics(e.g.,up to 99%in 25 min for tetracycline hydrochloride,TC),due to the generated reactive oxygen species(ROS),especially the dominant·O^(2−).It can fully inactivate E.coli(HB101)with initial number of~108 CFU mL^(−1) in 10 min,which is mainly attributed to the synergistic effects of 1D nanostructure,dissolved metal ions,and generated ROS.Meanwhile,it is able to damage ARGs after 180 min of photodegradation,including tetA(vs TC)of 3.3 log 10,aphA(vs kanamycin sulfate,KAN)of 3.4 log 10,and tnpA(vs ampicillin,AMP)of 4.4 log 10,respectively.This work explores a green way for treating antibiotic pollution under visible light.

Mobile genetic elements facilitate the transmission of antibiotic resistance genes in multidrug-resistant Enterobacteriaceae from duck farms

Multidrug-resistant(MDR)Enterobacteriaceae critically threaten duck farming and public health.The phenotypes,genotypes,and associated mobile genetic elements(MGEs)of MDR Enterobacteriaceae isolated from 6 duck farms in Zhejiang Province,China,were investigated.A total of 215 isolates were identified as Escherichia coli(64.65%),Klebsiella pneumoniae(12.09%),Proteus mirabilis(10.23%),Salmonella(8.84%),and Enterobacter cloacae(4.19%).Meanwhile,all isolates were resistant to at least two antibiotics.Most isolates carried tet(A)(85.12%),blaTEM(78.60%)and sul1(67.44%)resistance genes.Gene co-occurrence analysis showed that the resistance genes were associated with IS26 and integrons.A conjugative IncFII plasmid pSDM004 containing all the above MGEs was detected in Proteus mirabilis isolate SDM004.This isolate was resistant to 18 antibiotics and carried the blaNDM-5 gene.MGEs,especially plasmids,are the primary antibiotic resistance gene transmission route in duck farms.These findings provide a theoretical basis for the rational use of antibiotics in farms which are substantial for evaluating public health and food safety.

Fate and Behavior of Tetracycline Resistance Genes in Activated Carbon Adsorption

The accessibility of tetracycline resistance gene (tetG) into the pores of activated carbon (AC), as well as the impact of the pore size distribution (PSD) of AC on the uptake capacity of tetG, were investigated using eight types of AC (four coal-based and four wood-based). AC showed the capability to admit tetG and the average reduction of tetG for coal-based and wood-based ACs at the AC dose of 1 g·L-1 was 3.12 log and 3.65 log, respectively. The uptake kinetic analysis showed that the uptake of the gene followed the pseudo-second-order kinetics reaction, and the uptake rate constant for the coal-based and wood-based ACs was in the range of 5.97 × 10-12 - 4.64 × 10-9 and 7.02 × 10-11 - 1.59 × 10-8 copies·mg-1·min-1, respectively. The uptake capacity analysis by fitting the obtained experiment data with the Freundlich isotherm model indicated that the uptake constant (KF) values were 1.71 × 103 - 8.00 × 109 (copies·g-1)1-1/n for coal-based ACs and 7.00 × 108 - 3.00 × 1010 (copies·g-1)1-1/n for wood-based ones. In addition, the correlation analysis between KF values and pore volume as well as pore surface at different pore size regions of ACs showed that relatively higher positive correlation was found for pores of 50 - 100 Å, suggesting ACs with more pores in this size region can uptake more tetG. The findings of this study are valuable as reference for optimizing the adsorption process regarding antibiotic resistance-related concerns in drinking water treatment.

UV-Based Advanced Oxidation Processes for Antibiotic Resistance Control: Efficiency, Influencing Factors, and Energy Consumption

Antibiotic resistant bacteria(ARB)with antibiotic resistance genes(ARGs)can reduce or eliminate the effectiveness of antibiotics and thus threaten human health.The United Nations Environment Programme considers antibiotic resistance the first of six emerging issues of concern.Advanced oxidation processes(AOPs)that combine ultraviolet(UV)irradiation and chemical oxidation(primarily chlorine,hydrogen peroxide,and persulfate)have attracted increasing interest as advanced water and wastewater treatment technologies.These integrated technologies have been reported to significantly elevate the efficiencies of ARB inactivation and ARG degradation compared with direct UV irradiation or chemical oxidation alone due to the generation of multiple reactive species.In this study,the performance and underlying mechanisms of UV/chlorine,UV/hydrogen peroxide,and UV/persulfate processes for controlling ARB and ARGs were reviewed based on recent studies.Factors affecting the process-specific efficiency in controlling ARB and ARGs were discussed,including biotic factors,oxidant dose,UV fluence,pH,and water matrix properties.In addition,the cost-effectiveness of the UV-based AOPs was evaluated using the concept of electrical energy per order.The UV/chlorine process exhibited a higher efficiency with lower energy consumption than other UV-based AOPs in the wastewater matrix,indicating its potential for ARB inactivation and ARG degradation in wastewater treatment.Further studies are required to address the trade-off between toxic byproduct formation and the energy efficiency of the UV/chlorine process in real wastewater to facilitate its optimization and application in the control of ARB and ARGs.

Performance Parameters:Demobilization Antibiotic Resistant Bacteria(ARB)and Carrying Genes(ARG)in Wastewater Disinfection

The UV irradiation is used for removing Antibiotic Resistant Bacteria(ARB)and Antibiotic Resistance Genes(ARG)from wastewater treatment.Bacteriophages are viruses that infect within bacteria,are recognized for bacterial control.The influence of some parameters in quantification and performance influencing of pathogen demobilization could be considered in disinfection of wastewater.The comparison of Polyvalent phage(NE1)versus Coliphage(NE4)in suppressing a bacterium Escherichia coli(NDM-1:b-lactam-resistant)with UV irradiation was observed the efficacy in reduction of cells in the disinfection and parameter process.The results with the effect of UV-C irradiation on NDM-1 infected with 1%of NE4 showed a decrease of cells from 8×10^(6)to 2×10^(5)in 60 min with UV-C dose.The NDM1(E.coli)was infected with 1%of NE4(Polyvalent Phage)under magnetic stirring for 1 h,the cells count was 8×10^(6).After 1 h in UV-C e×posure,the cells number reached 3×10^(5).The NDM1 that was e×posed in 1 h of UV-C irradiation and then was infected with 1%of NE4.Cells counting were done 24 h after this procedure.These cells were e×posed in UV-C and showed a reduction in the number of cells from 1×10^(8)to 4×10^(5)after 60 min.The results indicate that bacteriophages can mitigate bacteria species,and combined the conventional water disinfection technologies that can support the microbial safety control strategies.

Distribution characteristics and removal rate of antibiotics and antibiotic resistance genes in different treatment processes of two drinking water plants

Emerging pollutants,such as antibiotics and antibiotic-resistance genes,are becoming increasingly important sources of safety and health concerns.Drinking water safety,which is closely related to human health,should receive more attention than natural water body safety.However,minimal research has been performed on the efficacy of existing treatment processes in water treatment plants for the removal of antibiotics and antibiotic resistance genes.To address this research gap,this study detected and analyzed six main antibiotics and nine antibiotic resistance genes in the treatment processes of two drinking water plants in Wuhan.Samples were collected over three months and then detected and analyzed using ultra-high-performance liquid chromatography-tandem mass spectrometry and fluorescence quantitation.The total concentrations of antibiotics and antibiotic resistance genes in the influent water of the two water plants were characterized as December>March>June.The precipitation and filtration processes of the Zou Maling Water Plant and Yu Shidun Water Plant successfully removed the antibiotics.The ozone-activated carbon process increased the removal rate of most antibiotics to 100%.However,a large amount of antibiotic resistance gene residues remained in the effluents of the two water plants.The experiments demonstrated that the existing ozone-activated carbon processes could not effectively remove antibiotic resistance genes.This study provides a reference for the optimization of drinking water treatment processes for antibiotics and antibiotic resistance gene removal.

Analysis of antibiotic resistance genes and their effects on marine environment

The application of overgrowth antibiotic resistance genes in marine research was discussed.Using the China National Knowledge Infrastructure(CNKI)network database to retrieve papers on resistance genes(n=30627)and antibiotic resistance genes(n=3277),the published trends,subject headings and other aspects of bibliometrics were analyzed.Literature in this field has increased rapidly in the past 38 years.55.3%of the papers were published in the last ten years,31.2%of the papers were published in the last five years.The relevance of research topics has increased in recent years,the current research mainly focus on antibiotics,resistance gene,antibiotic resistance gene,and drug resistance.Literature analysis is helpful to understand the overall development trend of overgrowth antibiotic resistance genes in marine research.

Genotyping Characteristics of Human Fecal Escherichia coli and Their Association with Multidrug Resistance in Miyun District, Beijing

Objective To explore the genotyping characteristics of human fecal Escherichia coli(E. coli) and the relationships between antibiotic resistance genes(ARGs) and multidrug resistance(MDR) of E. coli in Miyun District, Beijing, an area with high incidence of infectious diarrheal cases but no related data.Methods Over a period of 3 years, 94 E. coli strains were isolated from fecal samples collected from Miyun District Hospital, a surveillance hospital of the National Pathogen Identification Network. The antibiotic susceptibility of the isolates was determined by the broth microdilution method. ARGs,multilocus sequence typing(MLST), and polymorphism trees were analyzed using whole-genome sequencing data(WGS).Results This study revealed that 68.09% of the isolates had MDR, prevalent and distributed in different clades, with a relatively high rate and low pathogenicity. There was no difference in MDR between the diarrheal(49/70) and healthy groups(15/24).Conclusion We developed a random forest(RF) prediction model of TEM.1 + baeR + mphA + mphB +QnrS1 + AAC.3-IId to identify MDR status, highlighting its potential for early resistance identification. The causes of MDR are likely mobile units transmitting the ARGs. In the future, we will continue to strengthen the monitoring of ARGs and MDR, and increase the number of strains to further verify the accuracy of the MDR markers.

Effects of antibiotics on corncob supported solid-phase denitrification: Denitrification and antibiotics removal performance, mechanism, and antibiotic resistance genes

Solid-phase denitrification(SPD)has been used in wastewater treatment plant effluent to enhance nitrate removal,and antibiotics co-existing in the effluent is a common environmental problem.In this study,it was systematically investigated the effect of single trace sulfamethoxazole(SMX)/trimethoprim(TMP)and theirmixture on microbial denitrification performance,the antibiotics removal,and antibiotics resistance genes(ARGs)in corncob supported SPD system.The average denitrification rate was improved by 46.90%or 61.09%with single 50μg/L SMX or TMP,while there was no significant inhibition with mixed SMX and TMP.The abundance of dominant denitrifiers(Comamonadaceae family and Azospia)and fermentation bacteria(Ancalomicrobium)were consistent with the denitrification performance of different antibiotics groups.Single SMX and TMP achieved relatively higher denitrification gene and enzyme abundance.Mixed SMX and TMP improved the denitrification gene copies,but they reduced the key denitrification enzymes except for EC 1.7.7.2.Additionally,the removal efficiency of TMP(56.70%±3.18%)was higher than that of SMX(25.44%±2.62%)in single antibiotic group,and the existence of other antibiotics(i.e.SMX or TMP)had no significant impact on the TMP or SMX removal performance.Biodegradation was the main removal mechanism of SMX and TMP,while sludge and corncob adsorption contributed a little to their removal.SMX had the risk of sulfanilamide resistance genes(SRGs)dissemination.Furthermore,network analysis indicated that Niveibacterium and Bradyrhizobium were the potential hosts of SRGs,which promoted the horizontal transmission of ARGs.

Enhanced removal of antibiotic resistance genes during chicken manure composting after combined inoculation of Bacillus subtilis with biochar

This study explored the combined effects of Bacillus subtilis inoculation with biochar on the evolution of bacterial communities,antibiotic resistance genes(ARGs),and mobile genetic elements(MGEs)during the composting of chicken manure.The results showed that B.subtilis inoculation combined with biochar increased bacterial abundance and diversity as well as prolonged the compost thermophilic period.Promoted organic matter biodegradation and facilitated the organic waste compost humification process,reduced the proliferation of ARGs by altering the bacterial composition.Firmicutes and Actinobacteriota were the main resistant bacteria related to ARGs and MGEs.The decrease in ARGs and MGEs was associated with the reduction in the abundance of related host bacteria.Compost inoculation with B.subtilis and the addition of biochar could promote nutrient transformation,reduce the increase in ARGs and MGEs,and increase the abundance of beneficial soil taxa.

Prevalence of class 1 integron and its gene cassettes carrying antibiotic resistance genes in drinking water treatment and distribution systems

Class 1 integrons are vital mobile genetic elements involved in the environmental transmission of antibiotic resistance genes(ARGs).However,knowledge about the diversity and abundance of class 1 integrons and gene cassettes during drinking water treatment and distribution is still limited.In this study,we aimed to uncover the prevalence of class 1 integrons in the drinking water treatment and distribution systems with the combination of culture-dependent and culture-independent methods.Further,we applied the nanopore sequencing method to characterize the diversity and arrangement of ARGs carried by class 1 integron-associated gene cassettes.A total of 42 isolates were inti-positive among the 208 strains isolated from drinking water,which tended to confer multi-drug resistance compared with intll-negative isolates.The absolute abundance of the intl1 average i.15×10^(9) copies/L in the source water and underwent the most significant reduction of over 99.9%after liquid chiorine disinfection.Furthermore,nanopore sequencing revealed that the class 1 integron-associated gene cassettes carried 51 subtypes of ARGs in drinking water,mainly conferring resistance to aminoglycosides and trimethoprim.The treatment processes,especially liquid chlorine disinfection,reduced most of the ARGs carried by gene cassettes,though some of the ARG subtypes persisted along the treatment and distribution ike aac(6)-Il,aadA,and dfrB2.The antibiotic resistance gene cassette array laac(6')-Ⅱ arr was most frequently detected,especially in the chlorinated water.This study underlined that drinking water was potential reservoir for integron-mediated ARGs transfer,indicating that the health risks of resistance gene cassettes in class 1 integrons deserved urgent attention.

Occurrence and possible sources of antibiotic resistance genes in seawater of the South China Sea

Antibiotic resistance genes(ARGs)might have great effect on ecological security and human health.Oceans are important reservoirs that receive tremendous amounts of pollutants globally.However,information on the proliferation of ARGs in seawater is still limited.This study performed field sampling to investigate the occurrence and distribution of ARGs in seawater of the South China Sea,which is the deepest and largest sea in China.The results showed that the total absolute abundances of ARGs in seawater samples ranged from 2.1×10^(3)to 2.3×10^(4)copies/mL,with an of 5.0×10^(3)copies/mL and a range of 2.2×10^(3)–1.8×10^(4)copies/mL for those with mobile genetic elements(MGEs).Genes resistant to multidrug,aminoglycoside,tetracycline,and fluoroquinolone antibiotics accounted for 77.3%–88.6%of total ARGs in seawater.Proteobacteria and Cyanobacteria represented 32.1%–56.2%and 30.4%–49.5%of microbial community,respectively.Prochlorococcus_MIT9313 and Clade_la were the prevalent genera in seawater of the South China Sea.Complex co-occurrence relationship existed among ARGs,MGEs,and bacteria.Anthropogenic activities had critical influence on ARGs and MGEs.Hospital wastewater,wastewater treatment plant effluent,sewage,aquaculture tailwater,and runoff were determined as the important sources of ARGs in seawater of the South China Sea based on positive matrix factorization analysis.

Understanding the rapid spread of antimicrobial resistance genes mediated by IS26

Insertion sequences(ISs)promote the transmission of antimicrobial resistance genes(ARGs)across bacterial populations.However,their contributions and dynamics during the transmission of resistance remain unclear.In this study,we selected is26 as a representative transposable element to decipher the relationship between ISs and ARGs and to investigate their transfer features and transmission trends.We retrieved 2656 translocatable IS26-bounded units with ARGs(tiS26-bUs-ARGs)in complete bacterial genomes from the NCBI RefSeq database.In total,124 ARGs spanning 12 classes of antibiotics were detected,and the average contribution rate of IS26 to these genes was 41.2%.We found that IS26-bounded units(IS26-bUs)mediated extensive ARG dissemination within the bacteria of the Gammaproteobacteria class,showing strong transfer po-tential between strains,species,and even phyla.The Is26-bUs expanded in bacterial populations over time,and their temporal expansion trend was significantly correlated with antibiotic usage.This wide dissemination could be due to the nonspecific target site preference of is26.Finally,we experimentally confirmed that the introduction of a single copy of is26 could lead to the formation of a composite transposon mediating the transmission of“passenger”genes.These observations extend our knowledge of the IS26 and provide new insights into the mediating role of ISs in the dissemination of antibiotic resistance.

Health risk ranking of antibiotic resistance genes in the Yangtze River

Antibiotic resistance is an escalating global health concern,exacerbated by the pervasive presence of antibiotic resistance genes(ARGs)in natural environments.The Yangtze River,the world's third-longest river,traversing areas with intense human activities,presents a unique ecosystem for studying the impact of these genes on human health.Here,we explored ARGs in the Yangtze River,examining 204 samples from six distinct habitats of approximately 6000 km of the river,including free-living and particle-associated settings,surface and bottom sediments,and surface and bottom bank soils.Employing shotgun sequencing,we generated an average of 13.69 Gb reads per sample.Our findings revealed a significantly higher abundance and diversity of ARGs in water-borne bacteria compared to other habitats.A notable pattern of resistome coalescence was observed within similar habitat types.In addition,we developed a framework for ranking the risk of ARG and a corresponding method for calculating the risk index.Applying them,we identified water-borne bacteria as the highest contributors to health risks,and noted an increase in ARG risks in particle-associated bacteria correlating with heightened anthropogenic activities.Further analysis using a weighted ARG risk index pinpointed the ChengdueChongqing and Yangtze River Delta urban agglomerations as regions of elevated health risk.These insights provide a critical new perspective on ARG health risk assessment,highlighting the urgent need for strategies to mitigate the impact of ARGs on human health and to preserve the ecological and economic sustainability of the Yangtze River for future human use.

Evaluating human exposure to antibiotic resistance genes

Antibiotic resistance is an escalating global concern,leading to millions of annual fatalities.Antibiotic resistance genes(ARGs)present in bacteria equip them to withstand the effects of antibiotics.Intra-and interspecific ARGs transmission through horizontal gene transfer further exacerbates resistance dissemination.The presence of ARGs in the environment heightens the probability of human exposure via direct inhalation,ingestion,or contact with polluted air,food,or water,posing substantial biosafety and health hazards.Consequently,ARGs represent a critical focal point in public health and environmental safety and are classified as emerging contaminants.This perspective underscores the necessity to assess ARG exposure within the One Health framework and to accord greater attention to the mitigation strategies and tactics associated with ARGs.

Nanoplastics promote the dissemination of antibiotic resistance genes and diversify their bacterial hosts in soil

The wide application of plastics has led to the ubiquitous presence of nanoplastics and microplastics in terrestrial environments.However,few studies have focused on the mechanism underlying the effects of plastic particles on soil microbiomes and resistomes,especially the differences between nanoplastics and microplastics.This study investigated the microbiome and resistome in soil exposed to polystyrene microplastics(mPS)or nanoplastics(nPS)through 16S rRNA and shotgun metagenomic sequencing.Distinct microbial communities were observed between mPS and nPS exposure groups,and nPS exposure significantly changed the bacterial composition even at the lowest amended rate(0.01%,w/w).The abundance of antibiotic resistance genes(ARGs)in nPS exposure(1%)was 0.26 copies per cell,significantly higher than that in control(0.21 copies per cell)and mPS exposure groups(0.21 copies per cell).It was observed that nanoplastics,bacterial community,and mobile genetic elements(MGEs)directly affected the ARG abundance in nPS exposure groups,while in mPS exposure groups,only MGEs directly induced the change of ARGs.Streptomyces was the predominant host for multidrug in the control and mPS exposure,whereas the primary host was changed to Bacillus in nPS exposure.Additionally,exposure to nPS induced several bacterial hosts to exhibit possible multi-antibiotic resistance characteristics.Our results indicated that the effects of plastic particles on the soil microbial community were size-dependent,and nano-sized plastic particles exhibited more substantial impacts.Both microplastics and nanoplastics promoted ARG transfer and diversified their bacterial hosts.These findings bear implications for the regulation of plastic waste and ARGs.

Effects of combined antibiotics on nitrification, bacteria and antibiotic resistance genes in activated sludge: Insights from legacy effect of antibiotics

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

Identification and characterization of integron mediated antibiotic resistance in pentachlorophenol degrading bacterium isolated from the chemostat

A bacterial consortium was developed by continuous enrichment of microbial population isolated from sediment core of pulp and paper mill effluent in mineral salts medium（MSM） supplemented with pentachlorophenol（PCP） as sole source of carbon and energy in the chemostat.The consortia contained three bacterial strains.They were identified as Escherichia coli,Pseudomonas aeruginosa and Acinetobacter sp.by 16S rRNA gene sequence analysis.Acinetobacter sp.readily degraded PCP through the formation of tetrachloro-p-hydroquinone（TecH）,2-chloro-1,4-benzenediol and products of ortho ring cleavage detected by gas chromatograph/mass spectrometer（GC-MS）.Out of the three acclimated PCP degrading bacterial strains only one strain,Acinetobacter sp.showed the presence of integron gene cassette as a marker of its stability and antibiotic resistance.The strain possessed a 4.17 kb amplicon with 22 ORF＇s.The plasmid isolated from the Acinetobacter sp.was subjected to shotgun cloning through restriction digestion by BamHI,HindIII and SalI,ligated to pUC19 vector and transformed into E.coli XLBlue1α,and finally selected on MSM containing PCP as sole source of carbon and energy with ampicillin as antibiotic marker.DNA sequence analysis of recombinant clones indicated homology with integron gene cassette and multiple antibiotic resistance genes.

Extended role for insertion sequence elements in the antibiotic resistance of Bacteroides

The Bacteroides species are important micro-organisms, both in the normal physiology of the intestines and as frequent opportunistic anaerobic pathogens, with a deeply-rooted phylogenetic origin endowing them with some interesting biological features. Their prevalence in anaerobic clinical specimens is around 60%-80%, and they display the most numerous and highest rates of antibiotic resistance among all pathogenic anaerobes. In these antibiotic resistance mechanisms there is a noteworthy role for the insertion sequence(IS) elements, which are usually regarded as representatives of ‘selfish' genes; the IS elements of Bacteroides are usually capable of up-regulating the antibiotic resistance genes. These include the cep A(penicillin and cephalosporin), cfx A(cephamycin), cfi A(carbapenem), nim(metronidazole) and erm F(clindamycin) resistance genes. This is achieved by outwardoriented promoter sequences on the ISs. Although some representatives are well characterized, e.g., the resistance gene-IS element pairs in certain resistant strains, open questions remain in this field concerning a better understanding of the molecular biology of theantibiotic resistance mechanisms of Bacteroides, which will have clinical implications.

Mitigating microbiological risks of potential pathogens carrying antibiotic resistance genes and virulence factors in receiving rivers:benefits of wastewater treatment plant upgrade

Wastewater treatment plants(WWTPs)with additional tertiary ultrafiltration membranes and ozonation treatment can improve water quality in receiving rivers.However,the impacts of WWTP upgrade(WWTP-UP)on pathogens carrying antibiotic resistance genes(ARGs)and virulence factors(VFs)in rivers remain poorly understood.In this study,ARGs,VFs,and their pathogenic hosts were investigated in three rivers impacted by large-scale WWTP-UP.A five-year sampling campaign covered the periods before and after WWTP-UP.Results showed that the abundance of total metagenome-assembled genomes(MAGs)containing both ARGs and VFs in receiving rivers did not decrease substantially after WWTP-UP,but the abundance of MAGs belonging to pathogenic genera that contain both ARGs and VFs(abbreviated as PAVs)declined markedly.'Genome-resolved metagenomics further revealed that WWTP-UP not only reduced most types of VFs and ARGs in PAVs,but also effectively eliminated efflux pump and nutritional VFs carried by PAVs in receiving rivers.WWTP-UP narrowed the pathogenic host ranges of ARGs and VFs and mitigated the cooccurrence of ARGs and VFs in receiving rivers.These findings underline the importance of WWTPUP for the alleviation of pathogens containing both ARGs and VFs in receiving rivers。