Peroxyacetic acid (PAA) oxidation has received widespread concerns for organic pollutant degradation with low secondary pollution. Nanoconfinement is an effective means to enhance the REDOX process by regulating reactive oxygen species formation and shortening the mass transfer distance. Herein, nanoconfined Co species were encapsulated in carbon nanotubes (Co3O4-in-CNTs), with more active sites and faster electron transfer, and exhibited excellent catalytic capacity on PAA activation. Consequently, the PAA/Co3O4-in-CNTs system achieved 100 % removal of sulfadiazine (SDZ) within 5 min, which was kinetically 24 times faster than the unconfined one. CH3C(O)OO and CH3C(O)O were the vital contributors, and the Co(IV) and O-1(2) created non-radical oxidation pathways via electron transfer. Theoretical calculations revealed that the electron delocalization around Co-active sites and electron rearrangement induced by nanoconfinement promoted the Co(IV), O-1(2), CH3C(O)OO, and CH3C(O)O formation, thus accelerating SDZ removal process. Moreover, the PAA/Co3O4-in-CNTs system performed great stability under different environmental conditions.

Municipal wastewater treatment plants (MWTP) are the main gathering places for antibiotic resistance genes (ARGs) and pathogenic bacteria. In this study, plasma oxidation was applied to remove the ARGs and inhibit pathogenicity in the effluent. The experimental results demonstrated that approximately 1.32 log, 1.34 log, 2.39 log, and 2.80 log of aac(3)-II, bla(TEM-1), TetW, and TetC were removed within 25 min of the plasma treatment, respectively. center dot OH, O-1(2), O-3, H2O2, NO2-, and NO3- all contributed to ARG removal. Coexisting dissolved organic matter was also oxidized, which was positively related to ARG removal. Plasma oxidation led to a decrease in the diversity and richness of microbial communities; Parcubacteria and Proteobacteria were the main potential hosts of ARGs and mobile genetic elements. Integmn gene Mtn decreased by 2.46 log after plasma treatment, which was positively related to ARG removal. Gene expression related to ATP binding, DNA repair, gene transfer, and the cell membrane was reduced after plasma treatment, resulting in effective ARG removal. Furthermore, pathogenic genes related to lumpy skin disease, Niemann-Pick disease, polycystic kidney and hepatic disease were all down-regulated by plasma treatment. Overall, the plasma treatment inhibited the transmission risks of ARGs and pathogenicity in the effluent of MWTP.

Rivers are important vectors and reservoirs of antibiotics resistance genes (ARGs). Information regarding transmission and health risk of ARGs in river confluence is still lacking. In this study, metagenomics was used to distinguish contributions of human activities on ARGs and human pathogenic bacteria (HPB) in confluence of Fenhe, Weihe, and Yellow Rivers. Bacitracin resistance gene and bacA were the highest in all rivers, with 1.86 × 10-2-7.26 × 10-2 and 1.79 × 10-2-9.12 × 10-2 copies/16S rRNA copies, respectively. River confluence significantly increased the abundance of ARGs, especially at the confluence of three rivers with the highest 1.53 × 10-1 copies/16S rRNA copies. Antibiotic efflux and antibiotic target alteration were the dominant resistant mechanisms in three rivers. ARGs profiles were influenced by multiple factors, with the contributions of various factors ranked as microbial communities > physicochemical factors > human activities > mobile genetic elements (MGEs). Notably, human activities and animal feces were important potential contributors of ARGs in the Weihe River and Yellow River. Transposons, as the main MGEs in three rivers, played important roles in ARGs transfer. The confluence of three rivers had the highest abundance of MGEs with the greatest transfer potentials, and therefore exhibiting the largest exposure risk of ARGs with 232.4 copies/cap·d. Furthermore, correlations of ARGs, MGEs, and HPB in different rivers were constructed via co-occurrence modes to systematically illustrate the health risks of ARGs. This study firstly unveiled the transmission and health risk of ARGs in river confluence, providing supports for ARGs control in watershed.

Feces in livestock farms is a reservoir of antibiotic resistance genes (ARGs), which can disseminate into sur-rounding soil and air, bringing risks to human health. In this study, seasonal dissemination of ARGs in a livestock farm and implications for human exposure was explored. The experimental results showed that ARGs abundance basically ranked as feces > soil > air, and significant seasonal dependence was observed. The total ARGs in pig feces was relatively higher in autumn (109.7 copies g-1) and winter (1010.0 copies g-1), and lower in summer (105.0 copies g-1). Similarly, the lowest total ARGs in soil and air were also observed in summer. There were correlations among ARGs, integron intI1, and bacterial community. Total organic carbon was an important factor affecting ARGs distribution in the feces, and pH and moisture content significantly affected soil ARGs. The daily intakes of integron intI1 and ARGs from air were 10 degrees.5 copies h-1 and 102.3 copies h-1 for human exposure, respectively. Pseudomonas was a potential pathogenic host of blaTEM-1 in feces, Pseudomonas and Acinetobacter were potential pathogenic hosts of multiple ARGs in soil, while ARGs in air did not migrate into pathogens.

Spread of antibiotic-resistant genes (ARGs) is a global public safety issue and inhibition their transfer is imperative. In this study, a novel strategy using environmental free radical exposure was developed to inhibit conjugative transfer of ARGs (RP4 plasmid) in aqueous solutions. Long-time free radical (center dot OH, 1O2, and O2 center dot- ) exposure significantly suppressed the conjugative transfer frequency of ARGs between Escherichia coli (E. coli) strains, and center dot OH was more likely to attack ARG, thereby inhibiting the conjugate transfer frequency, compared to 1O2 and O2 center dot- . Compared with the control, the conjugative transfer frequency significantly decreased from 4.08 x 10-5 to 1.2 x 10-8 after 10 min free radical exposure, confirming that the transfer and proliferation of ARGs were well inhibited. Correspondingly, the number of transconjugant significantly decreased by 61.7% after 10 min free radical exposure. Significant reductions in reactive oxygen species levels (ROS content and enzyme levels) and DNA damage-induced responses in the donor strains were observed after 10 min free radical exposure. Concurrently, intercellular contact was also weakened via inhibiting the synthesis of polysaccharides in extracellular polymeric substances. Moreover, the expressions of plasmid transfer genes were down-regulated after 10 min exposure due to the shortage of adenosine-triphosphate supply. This study firstly disclosed the underneath mechanisms for depressing ARGs transfer and dissemination via environmental free radical exposure.

Antibiotic-resistant bacteria (ARB) and their resistance genes (ARGs), which are commonly detected in waters, are emerging environmental contaminants with strong pathogenicity. Simultaneous removal of ARB and ARGs in water by mesoporous plasma was explored in this study, focusing on evaluating the impacts of common inorganic ions on ARB inactivation, antibiotic resistance reduction, and change in ARGs profiles. The antibiotic resistant Escherichia coli (AR E. coli) was selected as the model ARB. The experimental results demonstrated that the presence of NO3-, Cu2+, and Fe2+ all promoted ARE. coli inactivation and ARGs elimination, reduced its antibiotic resistance, and also inhibited horizontal gene transfer of ARGs; whereas CO32- inhibited these processes, and SO42- did not have distinct effect. During the plasma treatment process, Fe2+ significant enhancement on (OH)-O-center dot formation via reactions with H2O, the highest performance was observed in the presence of Fe2+. The membrane structure, disruption of biological processes, dissolution of intracellular components, and DNA. These finding shed light on the potential effects of inorganic ions on ARB and ARGs elimination induced by the mesoporous plasma.

Dissemination of antibiotic resistance gene (ARG) is a huge challenge around the world. Natural organic matter (NOM) is one of the most commonly components in aquatic systems. Information regarding ARG transfer induced by NOM is still lacking. In this study, experimental exploration and model prediction on RP4 plasmid conjugative transfer between bacteria under NOM exposure was conducted. Compared with no exposure, the conjugative transfer frequency of RP4 plasmid increased 7.1-fold and 3.2-fold under exposure to 10 kDa and 100 kDa NOM exposure, respectively. NOM exposure with a lower molecular weight and higher concentration promoted gene expressions related to reactive oxygen species generation, cell membrane permeability, intercellular contact, quorum sensing, and energy driving force. Concurrently, the expressions of conjugation genes in RP4 plasmid were also upregulated. Moreover, model prediction demonstrated that the maintenance of the acquired plasmid was shortened to 133 h under 10 kDa NOM exposure compared with the control (200 h). Long-term NOM exposure enhanced transfer frequency and transfer rate of ARG. This study firstly theoretically and experi-mentally revealed the underlying mechanisms for promoting ARG transfer by NOM.

Antibiotic-resistant bacteria (ARB) and their resistance genes (ARGs), as emerging environmental pollutants, are commonly detected in waters. Surface plasma was developed to simultaneously inactivate antibiotic resistant Escherichia coli (AR E. coli) and remove its associated ARGs in water. 7.0 log AR E. coli was inactivated after 10 min surface plasma treatment; minimal inhibitory concentration (MIC) representing antibiotic resistance profiles decreased by 96.9%, 96.9%, and 98.4% for the tested tetracycline, amoxicillin, and gentamicin, respectively. The ARGs (TetC, TetW, bla(TEM)-1, and aac(3)-II) and integmn gene (intI1, indicator of horizontal gene transfer) also decreased by 1.04, 0.61, 1.84, 2.2, and 2.3 log copies within 10 min, respectively. Oxidizing substances in the surface plasma including (OH)-O-center dot, O-1(2), H2O2, O-3, NO2-, and NO3- contributed to AR E. coli inactivation, resulting in membrane damage, biological process disruption, protein structure changes, and DNA damage. As a result, horizontal gene transfer of ARGs was inhibited by 63% after plasma treatment. Overall, surface plasma could be an effective technique to control ARB and ARGs in water.

The prevalence of various antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) is becoming a global environmental problem. Removal of multiple resistant Escherichia coli strains, carrying a gentamicin resistance gene (aac(3)-II), an amoxicillin-resistance gene (blaTEM-1), tetracycline-resistance genes (tetC and tetW), and integron gene intI1, was investigated using a mesoporous plasma. The experimental results showed that the elimination efficiencies of integron intI1, aac(3)-II, blaTEM-1, tetW, and tetC reached 5.46, 5.71, 5.19, 2.88, and 2.28 log within 10 min of plasma oxidation, respectively. These elimination performances were positively related to the plasma intensity, duration time, and airflow rate. The cell membrane structures were significantly destroyed by the significantly destroyed by plasma oxidation, accompanied by leakage of ARG-containing DNA. Most of the ARG-containing DNA (more than 96%) was effectively damaged and decomposed to cytosine, guanine, adenine, and thymine. The present research revealed the removal behaviors of ARGs by plasma oxidation and provided an alternative to eliminate ARGs in an aqueous system.