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.

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.

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.

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.

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。

Co-occurrence of genes for antibiotic resistance and arsenic biotransformation in paddy soils

Paddy soils are potential hotspots of combined contamination with arsenic(As) and antibiotics, which may induce co-selection of antibiotic resistance genes(ARGs) and As biotransformation genes (ABGs), resulting in dissemination of antimicrobial resistance and modification in As biogeochemical cycling. So far, little information is available for these coselection processes and specific patterns between ABGs and ARGs in paddy soils. Here, the16S rRNA amplicon sequencing and high-throughput quantitative PCR and network analysis were employed to investigate the dynamic response of ABGs and ARGs to As stress and manure application. The results showed that As stress increased the abundance of ARGs and mobile genetic elements (MGEs), resulting in dissemination risk of antimicrobial resistance. Manure amendment increased the abundance of ABGs, enhanced As mobilization and methylation in paddy soil, posing risk to food safety. The frequency of the co-occurrence between ABGs and ARGs, the host bacteria carrying both ARGs and ABGs were increased by As or manure treatment, and remarkably boosted in soils amended with both As and manure. Multidrug resistance genes were found to have the preference to be co-selected with ABGs, which was one of the dominant co-occurring ARGs in all treatments, and manure amendment increased the frequency of Macrolide-Lincosamide-Streptogramin B resistance(MLSB) to co-occur with ABGs. Bacillus and Clostridium of Firmicutes are the dominant host bacteria carrying both ABGs and ARGs in paddy soils. This study would extend our understanding on the co-selection between genes for antibiotics and metals, also unveil the hidden environmental effects of combined pollution.

Metagenomic analysis to determine the characteristics of antibiotic resistance genes in typical antibiotic-contaminated sediments

Comprehensive studies of the effects of various physical and chemical variables(including heavymetals),antibiotics,and microorganisms in the environment on antibiotic resistance genes are rare.We collected sediment samples from the Shatian Lake aquaculture area and surrounding lakes and rivers located in Shanghai,China.The spatial distribution of sediment ARGs was assessed by metagenomic analysis that revealed 26 ARG types(510 subtypes),dominated by Multidrug,β-lactam,Aminoglycoside,Glycopeptides,Fluoroquinolone,and Tetracyline.Redundancy discriminant analysis indicated that antibiotics(SAs and MLs)in the aqueous environment and sediment along with water TN and TP were the key variables affecting the abundance distribution of total ARGs.However,the main environmental drivers and key influences differed among the different ARGs.For total ARGs,the environmental subtypes affecting their structural composition and distribution characteristics were mainly antibiotic residues.Procrustes analysis showed a significant correlation between ARGs and microbial communities in the sediment in the survey area.Network analysis revealed that most of the target ARGs were significantly and positively correlated with microorganisms,and a small number of ARGs(e.g.,rpoB,mdtC,and efpA)were highly significantly and positively correlated with microorganisms(e.g.,Knoellia,Tetrasphaera,and Gem-matirosa).Potential hosts for the major ARGs included Actinobacteria,Proteobacteria,and Gemmatimonadetes.Our study provides new insight and a comprehensive assessment of the distribution and abundance of ARGs and the drivers of ARG occurrence and transmission.

The fate of antibiotic resistance genes in the coastal lagoon with multiple functional zones

Coastal lagoons provide many important services to human society,but their year-round use for aquaculture introduces large amounts of sewage.The contamination of antibiotic resistance genes(ARGs)is therefore of great concern.In this study,50 ARGs subtypes,two integrase genes(intl1,intl2),and 16S rRNA genes were detected by high-throughput quantitative PCR,and standard curves of all target genes were prepared for quantification.The occurrence and distribution of ARGs in a typical coastal lagoon(XinCun lagoon,China)were comprehensively explored.We detected 44 and 38 subtypes of ARGs in the water and sediment,respectively,and discuss the various factors influencing the fate of ARGs in the coastal lagoon.Macrolides-lincosamides-streptogramins B was the primary ARG type,and macB was the predominant subtype.Antibiotic efflux and antibiotic inactivation were the main ARG resistance mechanisms.The XinCun lagoon was divided into eight functional zones.The ARGs showed a distinct spatial distribution owing to the influence of microbial biomass and anthropogenic activity in different functional zones.Fishing rafts,abandoned fish ponds,the town sewage zone,and mangrove wetlands provided a large quantity of ARGs to the XinCun lagoon.Nutrients and heavy metals also significantly correlated with the fate of the ARGs,especially NO_(2)^(−)-N and Cu,which cannot be ignored.It is noteworthy that lagoon-barrier systems coupled with persistent pollutant inputs result in coastal lagoons acting as a“buffer pool”for ARGs,which can then accumulate and threaten the offshore environment.

Effect of sulfamethazine on the horizontal transfer of plasmid-mediated antibiotic resistance genes and its mechanism of action

As a new type of environmental pollutant,antibiotic resistance genes(ARGs)pose a huge challenge to global health.Horizontal gene transfer(HGT)represents an important route for the spread of ARGs.The widespread use of sulfamethazine(SM2)as a broad-spectrum bacteriostatic agent leads to high residual levels in the environment,thereby increasing the spread of ARGs.Therefore,we chose to study the effect of SM2 on the HGT of ARGs mediated by plasmid RP4 from Escherichia coli(E.coli)HB101 to E.coli NK5449 as well as its mechanism of action.The results showed that compared with the control group,SM2 at concentrations of 10 mg/L and 200 mg/L promoted the HGT of ARGs,but transfer frequency decreased at concentrations of 100 mg/L and 500 mg/L.The transfer frequency at 200 mg/L was 3.04×10^(−5),which was 1.34-fold of the control group.The mechanism of SM2 improving conjugation transfer is via enhancement of the mRNA expression of conjugation genes(trbBP,trfAP)and oxidative stress genes,inhibition of the mRNA expression of vertical transfer genes,up regulation of the outer membrane protein genes(ompC,ompA),promotion of the formation of cell pores,and improvement of the permeability of cell membrane to promote the conjugation transfer of plasmid RP4.The results of this study provide theoretical support for studying the spread of ARGs in the environment.

Coastal mudflats as reservoirs of extracellular antibiotic resistance genes: Studies in Eastern China

Despite coastal mudflats serving as essential ecological zones interconnecting terrestrial/freshwater and marine systems,little is known about the profiles of antibiotic resistance genes(ARGs)in this area.In this study,characteristics of typical ARGs,involving both intracellular(iARGs)and extracellular ARGs(eARGs)at different physical states,were explored in over 1000 km of coastal mudflats in Eastern China.Results indicated the presence of iARGs and eARGs at states of both freely present or attached by particles.The abundance of eARGs was significantly higher than that of iARGs(87.3%vs 12.7%),and their dominance was more significant than those in other habitats(52.7%-76.3%).ARG abundance,especially for eARGs,showed an increasing trend(p<0.05)from southern(Nantong)to northern(Lianyungang)coastalmudflats.Higher salinity facilitated the transformation from iARGs to eARGs,and smaller soil particle size was conducive to the persistence of eARGs in northern coastal mudflats.This study addresses the neglected function of coastal mudflats as eARGs reservoirs.

Spatial distribution of bacterial resistance towards antibiotics of rural sanitation system in China and its potential link with diseases incidence

Chinese government is vigorously promoting toilet renovation in rural areas to reduce the risk of human feces exposure,which would cause infectious diseases,especially antibiotic resistance genes(ARGs)and pathogens.However,the distribution of ARGs in human feces from different regions of China remained ill-defined.It is not yet known how the survival of ARGs after toilet treatment is associated with the regional infection rates.Here,we investigated the prevalence of ARGs in human feces in rural areas of China and their potential relationship with infectious diseases for the first large-scale.The results showed that there were still high ARGs residues in human feces after rural toilet treatment,especially tetM-01 and ermB with average relative abundance as high as 1.21×10^(−1)(Eastern)and 1.56×10^(−1)(Northern),respectively.At a large regional scale,the significant differences in human feces resistomeswere mainly shaped by the toilet types,TN,NH_(3)-N,and the bacterial community.A critical finding was that toilets still cannot effectively decrease the pathogenicity risk in human feces.The significant positive relationship(P<0.05)between infectious diseases and ARGs can infer that ARGs in human feces exposure might be a critical path for enhancing the incidence of diseases,as these ARGs hinder the effectiveness of antibiotics.