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.

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.

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.

Effect of biofilm formation by clinical isolates of Helicobacter pylori on the efflux-mediated resistance to commonly used antibiotics

To evaluate the role of biofilm formation on the resistance of Helicobacter pylori (H. pylori) to commonly prescribed antibiotics, the expression rates of resistance genes in biofilm-forming and planktonic cells were compared.METHODSA collection of 33 H. pylori isolates from children and adult patients with chronic infection were taken for the present study. The isolates were screened for biofilm formation ability, as well as for polymerase chain reaction (PCR) reaction with HP1165 and hp1165 efflux pump genes. Susceptibilities of the selected strains to antibiotic and differences between susceptibilities of planktonic and biofilm-forming cell populations were determined. Quantitative real-time PCR (qPCR) analysis was performed using 16S rRNA gene as a H. pylori-specific primer, and two efflux pumps-specific primers, hp1165 and hefA.RESULTSThe strains were resistant to amoxicillin, metronidazole, and erythromycin, except for one strain, but they were all susceptible to tetracycline. Minimum bactericidal concentrations of antibiotics in the biofilm-forming cells were significantly higher than those of planktonic cells. qPCR demonstrated that the expression of efflux pump genes was significantly higher in the biofilm-forming cells as compared to the planktonic ones.CONCLUSIONThe present work demonstrated an association between H. pylori biofilm formation and decreased susceptibility to all the antibiotics tested. This decreased susceptibility to antibiotics was associated with enhanced functional activity of two efflux pumps: hp1165 and hefA.

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.

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.

The Role of Wastewater Treatment Plants in the Environmental Dissemination of Antibiotic Resistant Bacteria (ARB) and Resistance Genes (ARG)

This study was conducted to evaluate the influence of wastewater treatment processes on the prevalence of antibiotic resistance fecal coliform (FC) and antibiotic resistance genes (ARGs) of FC. In addition, the occurrence of antibiotic resistant bacteria (ARB) and antibiotic resistant genes (ARGs) in surface waters receiving wastewater was evaluated. Greater resistance against penicillin (P), colisitin (CT) and ampicillin (AMP) were observed for FC isolated from effluent disinfected by chlorine (71%), than that disinfected by UV (45%). The greatest resistance against six antibiotics was recorded for FC isolates from effluent disinfected by chlorine. The prevalence of tetB and blaSHV was lowest in isolates from chlorine-disinfected effluents. The occurrence of ARG blaSHV was highest in FC isolated from effluent disinfected by UV. A significant correlation was recorded between FC levels in surface waters and the level of bacterial resistance to ampicillin (P SHV in effluents and in surface waters. TetA and tetC were highly prevalent in surface water compared to tetB. The results of the study demonstrate the widespread prevalence of ARB and ARG in wastewater and receiving water bodies. The result indicates that the source of ARB and ARG in surface waters originate from wastewater. Released ARB and ARG may serve as the source of ARG to pathogenic bacteria in surface waters. Disinfection processes may influence the selection of antibiotic resistant patterns of bacteria.

Genetic Diversity,Antibiotic Resistance,and Pathogenicity of Aeromonas Species from Food Products in Shanghai,China

Objective Aeromonas has recently been recognized as an emerging human pathogen.Aeromonasassociated diarrhea is a phenomenon occurring worldwide.This study was designed to determine the prevalence,genetic diversity,antibiotic resistance,and pathogenicity of Aeromonas strains isolated from food products in Shanghai.Methods Aeromonas isolates(n=79)collected from food samples were analyzed using concatenated gyrB-cpn60 sequencing.The antibiotic resistance of these isolates was determined using antimicrobial susceptibility testing.Pathogenicity was assessed usingβ-hemolytic,extracellular protease,virulence gene detection,C.elegans liquid toxicity(LT),and cytotoxicity assays.Results Eight different species were identified among the 79 isolates.The most prevalent Aeromonas species were A.veronii[62(78.5%)],A.caviae[6(7.6%)],A.dhakensis[3(3.8%)],and A.salmonicida[3(3.8%)].The Aeromonas isolates were divided into 73 sequence types(STs),of which 65 were novel.The isolates were hemolytic(45.6%)and protease-positive(81.0%).The most prevalent virulence genes were act(73.4%),fla(69.6%),aexT(36.7%),and ascV(30.4%).The results of C.elegans LT and cytotoxicity assays revealed that A.dhakensis and A.hydrophila were more virulent than A.veronii,A.caviae,and A.bivalvium.Antibiotic resistance genes[tetE,blaTEM,tetA,qnrS,aac(6)-Ib,mcr-1,and mcr-3]were detected in the isolates.The multidrug-resistance rate of the Aeromonas isolates was 11.4%,and 93.7%of the Aeromonas isolates were resistant to cefazolin.Conclusion The taxonomy,antibiotic resistance,and pathogenicity of different Aeromonas species varied.The Aeromonas isolates A.dhakensis and A.hydrophila were highly pathogenic,indicating that food-derived Aeromonas isolates are potential risks for public health and food safety.The monitoring of food quality and safety will result in better prevention and treatment strategies to control diarrhea illnesses in China.

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.

Dissemination of Resistance Integrons and Genes Coding for Blse and Cabapenemases in the Urban Drainage Network in Cote d’Ivoire

Antibiotic resistance has become a major threat to human health worldwide. Environment, particularly the water environment, has long been overlooked as a player in the antibiotic resistance cycle, although its role remains unclear. These can provide an ideal setting for the acquisition and dissemination of antibiotic resistance, as they are frequently affected by anthropogenic activities. The objective of this study was to establish a diffusion map of resistance integrons used as genetic markers of resistance associated with antibiotic resistance conferring genes (ARGs). Total DNA extracts from non-cultivable bacterial communities were used for the analyses. These communities were obtained from wastewater samples from 14 sites upstream and downstream of drainage channels or effluents in the cities of Abidjan, Bouaké, and Yamoussoukro. The results obtained correspond to the number of positives among the treated samples (n = 39). Among the genetic markers of dissemination, class 1 integrons were the most evident in 94.8% of samples in Abidjan (93.3%), Bouaké (100%) and Yamoussoukro (91.6%). Class 2 integrons and class 3 integrons were found respectively in 41% and 51% of all samples. Genes coding for β-lactamases and blaTEM was identified in almost all samples at a rate of 97.4%. A co-presence of the three genes blaTEM, blaSHV and blaCTX-M is also remarkable in the sites of the city of Yamoussoukro. Among the genes coding for carbapenemases, only blaKPC 17.94%, blaNDM 30.76% and blaOXA48 38.46% were detected in the samples.

Characteristics of microbial communities and antibiotic resistance genes in typical rivers of the western Qinghai Lake basin

Environmental factors and anthropogenic activity are key factors that shape the distribution of bacteria and antibiotic resistance genes(ARGs)in natural environments.However,few studies have focused on the occurrence of bacteria and ARGs in remote and pristine environments.In this study,the distribution of bacteria and ARGs in two typical rivers of the western Qinghai Lake basin was investigated.Results showed that cold-resistant Planomicrobium sp.was the predominant genus due to the low temperature,followed by unclassified_f_Planococcaceae.High nitrogen nutrients increased the abundance and diversity of the bacteria community and denitrification was the dominant means of bacterial nitrate reduction.Tetracycline resistance genes including tetA,tetB,and tetC were the dominant ARGs in the western Qinghai Lake basin,ranging from 2.30×10^(3)to 1.91×10^(8)copies/L,while the low abundances of intI1,and ARGs such as sul1 indicated low anthropogenic activity in the western Qinghai Lake basin.Finally,the strong positive correlation between ARGs and intI1 highlights the potential transmission risk of ARGs through cross-or co-selection by horizontal gene transfer.Our study emphasized the adaptation of bacteria to the environment and the facilitation of anthropogenic activity in the propagation of ARGs in natural environments.

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.

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.

Streptococcus peumoniae in an Egyptian urban community:incidence of erythromycin-resistance determinants and antibiotic susceptibility profile

Objectives:To determine the incidence of resistance of Streptococcus(Strep).pneumoniae isolated in our locality to erythromycin,to screen for the two resistance determinants erm(B) and mef(A) genes,and to identify the susceptibility profile to commonly used antibiotics.Methods:Samples were collected from patients attending the Outpatient Department of Zagazig University Hospital,Zagazig,Egypt,between February 2006 and March 2007.Strep.pneumoniae was identified by conventional procedures.Susceptibilities to erythromycin and 15 antibiotics were identified by disc diffusion method,as outlined by CLSI.E-test was used for MIC determination of erythromycin.erm(B) and mef(A) genes were detected by PCR.Results:Eighty-one Strep. pneumoniae strains were identified.Fifty- one of them(63%) were erythromycin-resistant,and mef(A) gene was the predominant resistance determinant.Vancomycin,imipenem and gatifloxacin had the best activity against the isolates,whereas tetracycline had the least.Forty-two(51.85%) out of the 81 Strep.pneumoniae strains were multidrug-resistant.Conclusions:High incidence of resistance to erythromycin and multiple antimicrobials existed.mef(A) was the principal erythromycin-resistance gene.

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.

Antibiotic resistance analysis and coping strategies of helicobacter pylori

Helicobacter pylori(H.pylori)is a Gram-negative bacterium that mainly colonizes the stomach and duodenum,and it can cause gastrointestinal diseases such as gastric inflammation,peptic ulcer and gastric cancer,and eradication of H.pylori can effectively stop the occurrence and development of gastrointestinal diseases.Antibiotics are one of the main drugs used to treat H.pylori.Due to the long-term application of antibiotics,the resistance rate of H.pylori to antibiotics increases year by year,which greatly reduces the eradication rate of H.pylori and increases the difficulty of re-treatment and the economic burden of patients.In this paper,we will review three aspects of H.pylori resistance status,resistance mechanism and treatment to provide reference for the progress of H.pylori resistance research and its treatment strategy.

Frequency of Antibiotic Resistance of <i>Escherichia coli</i>and <i>Klebsiella pneumoniae</i>by Production of TOHO-Type <i>β</i>-Lactamases at Saint Camille Hospital, Ouagadougou (Burkina Faso)

Extended-spectrum β-lactamase (ESBL) appeared some years after the introduction in hospital environment of unhydrolysable or extended-spectrum cephalosporins. Several studies have been reported on the blaTEM, blaCTX-M and blaSHV genes in ESBL producing Enterobacteria, however, very few studies reported in the literature were related to blaCTX-M subgroup blaTOHO. TOHO enzymes were responsible for healthcare-associated infections in hospitals and in the community. In Burkina Faso, data related to these types of enzymes were scarce. The purpose of this study was to detect TOHO enzymes in Escherichia coli and Klebsiella pneumoniae in order to know the prevalence of infections related to bacterial resistance due to TOHO enzymes at Saint Camille Hospital of Ouagadougou (Burkina Faso). The study was conducted firstly by microbiological identification of ESBLs-producing by Escherichia coli and Klebsiella pneumoniae using API 20 E gallery;secondly the antibiogram was performed by the diffusion method and finally the molecular characterization was made by conventional PCR to search for the blaTOHO gene. The visualization of the specific bands was made using the ultraviolet lamp (Gene Flash) for the photography of the gels. Data were entered and analyzed using Excel 2013 and EPI Info version 6.0 software. A p-value < 0.05 was considered as significant. We obtained at all 39 strains constituted by 21 (53.8%) Escherichia coli and 18 (46.2%) Klebsiella pneumoniae. Molecular characterization showed the presence of the blaTOHO gene in 25 bacterial strains (64.1%). It was therefore established in this study the existence of blaTOHO gene at Saint Camille Hospital in Ouagadougou in Burkina Faso. Our study made it possible to know the distribution of the blaTOHO gene in Escherichia coli and Klebsiella pneumoniae.

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.

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.

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.