KANA - Word Related Documents




#
Rank
Similarity
Title + Abs.
Year
PMID
012345
973700.8808Zinc Finger Nuclease: A New Approach to Overcome Beta-Lactam Antibiotic Resistance. BACKGROUND: The evolution of antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs) has been accelerated recently by the indiscriminate application of antibiotics. Antibiotic resistance has challenged the success of medical interventions and therefore is considered a hazardous threat to human health. OBJECTIVES: The present study aimed to describe the use of zinc finger nuclease (ZFN) technology to target and disrupt a plasmid-encoded β-lactamase, which prevents horizontal gene transfer-mediated evolution of ARBs. MATERIALS AND METHODS: An engineered ZFN was designed to target a specific sequence in the ampicillin resistance gene (amp(R)) of the pTZ57R plasmid. The Escherichia coli bacteria already contained the pZFN kanamycin-resistant (kana(R)) plasmid as the case or the pP15A, kana(R) empty vector as the control, were transformed with the pTZ57R; the ability of the designed ZFN to disrupt the β-lactamase gene was evaluated with the subsequent disturbed ability of the bacteria to grow on ampicillin (amp) and ampicillin-kanamycin (amp-kana)-containing media. The effect of mild hypothermia on the ZFN gene targeting efficiency was also evaluated. RESULTS: The growth of bacteria in the case group on the amp and amp-kana-containing media was significantly lower compared with the control group at 37°C (P < 0.001). Despite being more efficient in hypothermic conditions at 30°C (P < 0.001), there were no significant associations between the incubation temperature and the ZFN gene targeting efficiency. CONCLUSIONS: Our findings revealed that the ZFN technology could be employed to overcome ampicillin resistance by the targeted disruption of the ampicillin resistance gene, which leads to inactivation of β-lactam synthesis. Therefore, ZFN technology could be engaged to decrease the antibiotic resistance issue with the construction of a ZFN archive against different ARGs. To tackle the resistance issue at the environmental level, recombinant phages expressing ZFNs against different ARGs could be constructed and released into both hospital and urban wastewater systems.201627099691
786810.8768A double-quenching paperclip ECL biosensing platform for ultrasensitive detection of antibiotic resistance genes (mecA) based on Ti(3)C(2) MXene-Au NPs as a coreactant accelerator. The global spread of environmental biological pollutants, such as antibiotic-resistant bacteria and their antibiotic resistance genes (ARGs), has emerged as a critical public health concern. It is imperative to address this pressing issue due to its potential implications for public health. Herein, a DNA paperclip probe with double-quenching function of target cyclic cleavage was proposed, and an electrochemiluminescence (ECL) biosensing platform was constructed using Ti(3)C(2) MXene in-situ reduction growth of Au NPs (TCM-Au) as a coreactant accelerator, and applied to the sensitive detection of ARGs. Thanks to the excellent catalytic performance, large surface area and Au-S affinity of TCM-Au, the ECL performance of CdS QDs have been significantly improved. By cleverly utilizing the negative charge of the paperclip nucleic acid probe and its modification group, double-quenching of the ECL signal was achieved. This innovative approach, combined with target cyclic amplification, facilitated specific and sensitive detection of the mecA gene. This biosensing platform manifested highly selective and sensitive determination of mecA genes in the range of 10 fM to 100 nM and a low detection limit of 2.7 fM. The credible detectability and anti-interference were demonstrated in Yangtze river and Aeration tank outlet, indicating its promising application toward pollution monitoring of ARGs.202337666010
782820.8744Simultaneous elimination of antibiotic-resistant bacteria and antibiotic resistance genes by different Fe-N co-doped biochars activating peroxymonosulfate: The key role of pyridine-N and Fe-N sites. The coexistence of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) in the environment poses a potential threat to public health. In our study, we have developed a novel advanced oxidation process for simultaneously removing ARGs and ARB by two types of iron and nitrogen-doped biochar derived from rice straw (FeN-RBC) and sludge (FeN-SBC). All viable ARB (approximately 10(8) CFU mL(-1)) was inactivated in the FeN-RBC/ peroxymonosulfate (PMS) system within 40 min and did not regrow after 48 h even in real water samples. Flow cytometry identified 96.7 % of dead cells in the FeN-RBC/PMS system, which verified the complete inactivation of ARB. Thorough disinfection of ARB was associated with the disruption of cell membranes and intracellular enzymes related to the antioxidant system. Whereas live bacteria (approximately 200 CFU mL(-1)) remained after FeN-SBC/PMS treatment. Intracellular and extracellular ARGs (tetA and tetB) were efficiently degraded in the FeN-RBC/PMS system. The production of active species, primarily •OH, SO(4)(•-) and Fe (IV), as well as electron transfer, were essential to the effective disinfection of FeN-RBC/PMS. In comparison with FeN-SBC, the better catalytic performance of FeN-RBC was mainly ascribed to its higher amount of pyridine-N and Fe(0), and more reactive active sites (such as CO group and Fe-N sites). Density functional theory calculations indicated the greater adsorption energy and Bader charge, more stable Fe-O bond, more easily broken OO bond in FeN-RBC/PMS, which demonstrated the stronger electron transfer capacity between FeN-RBC and PMS. To encapsulate, our study provided an efficient and dependable method for the simultaneous elimination of ARGs and ARB in water.202438669989
793530.8742Removal of antibiotic resistance genes by Cl(2)-UV process: Direct UV damage outweighs free radicals in effectiveness. Antibiotic resistance genes (ARGs) pose significant environmental health problems and have become a major global concern. This study investigated the efficacy and mechanism of the Cl(2)-UV process (chlorine followed by UV irradiation) for removing ARGs in various forms. The Cl(2)-UV process caused irreversible damage to nearly all ARB at typical disinfectant dosages. In solutions containing only extracellular ARGs (eARGs), the Cl₂-UV process achieved over 99.0 % degradation of eARGs. When both eARGs and intracellular ARGs (iARGs) were present, the process reached a 97.2 % removal rate for iARGs. While the abundance of eARGs initially increased due to the release of iARGs from lysed cells during pre-chlorination, subsequent UV irradiation rapidly degraded the released eARGs, restoring their abundance to near-initial levels by the end of the Cl₂-UV process. Analysis of the roles in degrading eARGs and iARGs during the Cl(2)-UV process revealed that UV, rather than free radicals, was the dominant factor causing ARG damage. Pre-chlorination enhanced direct UV damage to eARGs and iARGs by altering plasmid conformation and promoting efficient damage to high UV-absorbing cellular components. Furthermore, no further natural transformation of residual ARGs occurred following the Cl(2)-UV treatment. This study demonstrated strong evidence for the effectiveness of the Cl(2)-UV process in controlling antibiotic resistance.202540048777
780440.8739Electrochemical flow-through disinfection reduces antibiotic resistance genes and horizontal transfer risk across bacterial species. Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), as emerging pollutants, are released into environment, increasing the risk of horizontal gene transfer (HGT). However, a limited number of studies quantified the effects of ARB disinfection on the HGT risk. This study investigated the inactivation of E. coli 10667 (sul) and the release and removal of ARGs using an electrochemical flow-through reactor (EFTR). Furthermore, the transfer frequencies and potential mechanisms of HGT after disinfection were explored using non-resistant E. coli GMCC 13373 as the recipient and E. coli DH5α carrying plasmid RP4 as the donor. A threshold of current density (0.25 mA/cm(2)) was observed to destroy cells and release intracellular ARGs (iARGs) to increase extracellular ARGs (eARGs) concentration. The further increase in the current density to 1 mA/cm(2) resulted in the decline of eARGs concentration due to the higher degradation rate of eARGs than the release rate of iARGs. The performance of ARGs degradation and HGT frequency by EFTR were compared with those of conventional disinfection processes, including chlorination and ultraviolet radiation (UV). A higher ARGs degradation (83.46%) was observed by EFTR compared with that under chlorination (10.23%) and UV (27.07%). Accordingly, EFTR reduced the HGT frequency (0.69) of released ARGs into the recipient (Forward transfer), and the value was lower than that by chlorination (2.69) and UV (1.73). Meanwhile, the surviving injured E. coli 10667 (sul) with increased cell permeability was transferred by plasmid RP4 from the donor (Reverse transfer) with a higher frequency of 0.33 by EFTR compared with that under chlorination (0.26) and UV (0.16). In addition, the sul3 gene was the least resistant to EFTR than sul1 and sul2 gene. These findings provide important insights into the mechanism of HGT between the injured E. coli 10667 (sul) and environmental bacteria. EFTR is a promising disinfection technology for preventing the spread of antibiotic resistance.202235085844
782950.8735Insights into capture-inactivation/oxidation of antibiotic resistance bacteria and cell-free antibiotic resistance genes from waters using flexibly-functionalized microbubbles. The spread of antibiotic resistance in the aquatic environment severely threatens the public health and ecological security. This study investigated simultaneously capturing and inactivating/oxidizing the antibiotic resistant bacteria (ARB) and cell-free antibiotic resistance genes (ARGs) in waters by flexibly-functionalized microbubbles. The microbubbles were obtained by surface-modifying the bubbles with coagulant (named as coagulative colloidal gas aphrons, CCGAs) and further encapsulating ozone in the gas core (named as coagulative colloidal ozone aphrons, CCOAs). CCGAs removed 92.4-97.5% of the sulfamethoxazole-resistant bacteria in the presence of dissolved organic matter (DOM), and the log reduction of cell-free ARGs (particularly, those encoded in plasmid) reached 1.86-3.30. The ozone release from CCOAs led to efficient in-situ oxidation: 91.2% of ARB were membrane-damaged and inactivated. In the municipal wastewater matrix, the removal of ARB increased whilst that of cell-free ARGs decreased by CCGAs with the DOM content increasing. The ozone encapsulation into CCGAs reinforced the bubble performance. The predominant capture mechanism should be electrostatic attraction between bubbles and ARB (or cell-free ARGs), and DOM enhanced the sweeping and bridging effect. The functionalized microbubble technology can be a promising and effective barrier for ARB and cell-free ARGs with shortened retention time, lessened chemical doses and simplified treatment unit.202235063836
849260.8730Promotion effects and mechanisms of molybdenum disulfide on the propagation of antibiotic resistance genes in soil. The rapid development of nanotechnology has aroused considerable attentions toward understanding the effects of engineered nanomaterials (ENMs) on the propagation of antibiotic resistance. Molybdenum disulfide (MoS(2)) is an extensively used ENM and poses potential risks associated with environmental exposure; nevertheless, the role of MoS(2) toward antibiotic resistance genes (ARGs) transfer remains largely unknown. Herein, it was discovered that MoS(2) nanosheets accelerated the horizontal transfer of RP4 plasmid across Escherichia coli in a dose-dependent manner (0.5-10 mg/L), with the maximum transfer frequency 2.07-fold higher than that of the control. Integration of physiological, transcriptomics, and metabolomics analyses demonstrated that SOS response in bacteria was activated by MoS(2) due to the elevation of oxidative damage, accompanied by cell membrane permeabilization. MoS(2) promoted bacterial adhesion and intercellular contact via stimulating the secretion of extracellular polysaccharides. The ATP levels were maximally increased by 305.7 % upon exposure to MoS(2), and the expression of plasmid transfer genes was up-regulated, contributing to the accelerated plasmid conjugation and increased ARG abundance in soil. Our findings highlight the roles of emerging ENMs (e.g., MoS(2)) in ARGs dissemination, which is significant for the safe applications and risk management of ENMs under the development scenarios of nanotechnology.202337062264
849370.8728Effects and mechanisms of plant growth regulators on horizontal transfer of antibiotic resistance genes through plasmid-mediated conjugation. A vast number of bacteria occur in both soil and plants, with some of them harboring antibiotic resistance genes (ARGs). When bacteria congregate on the interface of soil particles or on plant root surfaces, these ARGs can be transferred between bacteria via conjugation, leading to the formation of antibiotic-resistant pathogens that threaten human health. Plant growth regulators (PGRs) are widely used in agricultural production, promoting plant growth and increasing crop yields. However, until now, little information has been known about the effects of PGRs on the horizontal gene transfer (HGT) of ARGs. In this study, with Escherichia coli DH5α (carrying RP4 plasmid with Tet(R), Amp(R), Kan(R)) as the donor and E. coli HB101 as the recipient, a series of diparental conjugation experiments were conducted to investigate the effects of indoleacetic acid (IAA), ethel (ETH) and gibberellin (GA(3)) on HGT of ARGs via plasmid-mediated conjugation. Furthermore, the mechanisms involved were also clarified. The results showed that all three PGRs affected the ARG transfer frequency by inducing the intracellular reactive oxygen species (ROS) formation, changing the cell membrane permeability, and regulating the gene transcription of traA, traL, trfAp, trbBp, kilA, and korA in plasmid RP4. In detail, 50-100 mg⋅L(-1) IAA, 20-50 mg⋅L(-1) ETH and 1500-2500 mg⋅L(-1) GA(3) all significantly promoted the ARG conjugation. This study indicated that widespread use of PGRs in agricultural production could affect the HGT of ARGs via plasmid-mediated conjugation, and the application of reasonable concentrations of PGRs could reduce the ARG transmission in both soil environments and plants.202336720410
858580.8728Synergistic effect of horizontal transfer of antibiotic resistance genes between bacteria exposed to microplastics and per/polyfluoroalkyl substances: An explanation from theoretical methods. Microplastics (MPs) and per/polyfluoroalkyl substances (PFASs), as emerging pollutants widely present in aquatic environments, pose a significant threat to human health through the horizontal gene transfer (HGT) of antibiotic resistance genes (ARGs). Molecular dynamics simulations and machine learning can accurately capture the complex interactions between molecules. This study utilized them to identify the HGT risk between bacteria under MPs and PFASs stress. This study found that MPs and PFASs significantly increase the HGT risk between bacteria, up to 1.57 and 1.59 times, respectively. Notably, long-chain PFASs and perfluoroalkyl carboxylic acids increased the HGT risk by 1.38 and 1.40 times, respectively. Additionally, MPs primarily increase the HGT risk by enhancing hydrogen bonding interaction between key proteins in the HGT pathway and "active codons". The electronegativity and polarizability of PFASs critically influence the HGT risk, acting inversely and directly proportional, respectively. The HGT risk between bacteria under the combined stress from PP-MPs and PFASs exhibits a significant synergistic effect (synergistic effect value of 27.6), which markedly increases the HGT risk. Further analysis revealed that a smaller minimum distance and sharper RDF curve peaks between key proteins and "active codons" indicate higher HGT risk. This indicates that stronger interactions lead to higher HGT risk. This study identifies the characteristics of HGT risks between bacteria in aquatic environments under the individual and combined stresses from MPs and PFASs at the molecular level. It provides a theoretical basis for mitigating ARG transfer and comprehensively assessing the health risks posed by these emerging pollutants.202540220390
785590.8727Combat against antibiotic resistance genes during photo-treatment of magnetic Zr-MOFs@Layered double hydroxide heterojunction: Conjugative transfer risk mitigating and bacterial inactivation. The dissemination of antimicrobial resistance (AMR) in wastewater treatment poses a severe threat to the global ecological environment. This study explored the effectiveness of photocatalysis in inactivating antibiotic resistant bacteria (ARB) and quantitatively clarified the inhibiting rate of the transfer of antibiotics resistance genes (ARGs). Herein, the magnetic heterojunction as UiO-66-NH(2)@CuFe LDH-Fe(3)O(4) (UN-66@LDH-Fe) effectively facilitated the electron-hole separation and accelerated the photogenerated charge transfer, thereby guaranteeing the stable practical application in aeration tanks. Notably, the internal electric field of heterogeneous photocatalyst resulted in significant increase of ARGs inactivation, achieving 5.63 log of ARB, 3.66 log of tetA and 3.57 log of Ampr genes were photodegraded under optimal reaction conditions within 6 h. Based on the complex microbial and molecular mechanism of multiple-ARB communities inactivation in photo-treatment, the photogenerated reactive oxygen species (ROSs, ·OH and ·O(2)(-)) effectively destroyed bacterial membrane protein, thereby the intracellular ROSs and redox cycles further induced oxidative stress, attributing to the abundance reduction of ARGs and their host bacteria. Moreover, long-term (7 days) continuous operation preliminarily verified the practical potential in reducing AMR spread and developing wastewater treatment efficacy. Overall, this study presented an advantageous synergistic strategy for mitigating the AMR-associated environmental risk in wastewater treatment.202540188541
8491100.8726Hormesis-like effects of black phosphorus nanosheets on the spread of multiple antibiotic resistance genes. The production scalability and increasing demand for black phosphorus nanosheets (BPNSs) inevitably lead to environmental leakage. Although BPNSs' ecotoxicological effects have been demonstrated, their indirect health risks, such as inducing increased resistance in pathogenic bacteria, are often overlooked. This study explores the influence of BPNSs on the horizontal gene transfer of antibiotic resistance genes (ARGs) facilitated by the RP4 plasmid, which carries multiple resistance genes. The results indicated that BPNSs exhibited concentration-dependent hormesis-like effects on bacterial conjugation gene transfer. Specifically, at sub-inhibitory concentrations (0.0001-1 mg/L), BPNSs promoted both intra- and intergeneric conjugative transfer, demonstrating an initial increase followed by a decline, with transfer rates rising by 1.5-3.1-fold and 1.5-3.3-fold, respectively. BPNSs were found to induce reactive oxygen species (ROS) production, increase malondialdehyde levels, and trigger the SOS response, enhancing plasmid uptake. Additionally, BPNSs increased membrane permeability by forming pores and upregulating outer membrane porins (OMPs) genes. At higher BPNSs concentrations (0.1-1 mg/L), conjugative frequency was inhibited due to the disruption of the cellular antioxidant system and changes in the adsorption process. These findings underscore the influence of BPNSs on the conjugative transfer of ARGs, complementing current knowledge of the biotoxicity and potential ecological risks associated with BPNSs.202539827804
7861110.8722The removal of antibiotic resistant bacteria and genes and inhibition of the horizontal gene transfer by contrastive research on sulfidated nanoscale zerovalent iron activating peroxymonosulfate or peroxydisulfate. Antibiotic resistant bacteria (ARB) and the antibiotic resistance genes (ARGs) dissemination via plasmid-mediated conjugation have attracted considerable attentions. In this research, sulfidated nanoscale zerovalent iron (S-nZVI)/peroxymonosulfate (PMS) and S-nZVI/peroxydisulfate (PDS) process were investigated to inactivate ARB (Escherichia coli DH5α with RP4 plasmid, Pseudomonas. HLS-6 contains sul1 and intI1 on genome DNA sequence). S-nZVI/PMS system showed higher efficiency than S-nZVI/PDS on ARB inactivation. Thus, the optimal condition 28 mg/L S-nZVI coupled with 153.7 mg/L (0.5 mM) PMS was applied to remove both intracellular ARGs (iARGs) and ARB. The oxidative damage of ARB cell was systemically studied by cell viability, intracellular Mg(2+) levels, the changes of extracellular and internal structure, integrity of cell walls and membranes and enzymatic activities. S-nZVI/PMS effectively inactivated ARB (~7.32 log) within 15 min. These effects were greatly higher than those achieved individually. Moreover, removal efficiencies of iARGs sul1, intI1 and tetA were 1.52, 1.79 and 1.56 log, respectively. These results revealed that S-nZVI and PMS have a synergistic effect against ARB and iARGs. The regrowth assays illustrated that the ARB were effectively inactivated. By verifying the inhibitory impacts of S-nZVI/PMS treatment on conjugation transfer, this work highlights a promising alternative technique for inhibiting the horizontal gene transfer.202234482079
7989120.8722Feasibility of sulfate-calcined eggshells for removing pathogenic bacteria and antibiotic resistance genes from landfill leachates. High abundance of human pathogen and antibiotic resistance genes (ARGs) in landfill leachate has become an emerging threat against human health. Therefore, sulfate- and calcination-modified eggshells as green agricultural bioresource were applied to test the feasibility of removing pathogenic bacteria and ARGs from leachate. The highest removal of Escherichia coli (E. coil) and gentamycin resistant gene (gmrA) from artificial contaminated landfill leachate was achieved by the application of eggshell with combined treatment of sulfate and calcination. The 16S and gmrA gene copies of E. coil declined significantly from 1.78E8±8.7E6 and 4.12E8±5.9E6 copies mL(-1) to 1.32E7±2.6E6 and 2.69E7±7.2E6 copies mL(-1), respectively, within 24h dynamic adsorption equilibrium process (p<0.05). Moreover, according to the Langmuir kinetic model, the greatest adsorption amount (1.56×10(9) CFU E. coil per gram of modified eggshells) could be obtained at neutral pH of 7.5. The optimal adsorption eggshells were then screened to the further application in three typical landfill leachates in Nanjing, eastern China. Significant decrease in species and abundance of pathogenic bacteria and ARGs (tet, sul, erm, qnr, and ampC) indicated its great efficiency to purify landfill leachates. This study demonstrated that sulfate-calcined eggshells can be an environmentally-friendly and highly efficient bioadsorbent to the management of reducing dissemination risk of pathogen and ARGs in landfill leachate.201728343745
7988130.8721Electrokinetic treatment at the thermophilic stage achieves more effective control of heavy metal resistance in swine manure composting. Excessive heavy metals (HMs) and metal resistance genes (MRGs) in manure pose significant environmental and human health risks. Our previous work proved enhanced control of antibiotic resistance and quality of swine manure composting with electrokinetic technology (EK). As a continuous study, EK treatments were further employed at typical stages of composting. The humification level increased significantly in EK treatments applied at the thermophilic stage (EK1) and throughout the whole composting period (EK2). The immobilization efficiency of heavy metals increased by 3.02 %-20.90 % for EK1, and 3.86 %-20.56 % for EK2, compared with the EK treatment applied at maturity stage (EK3). EK1 showed the highest ability to remove MRGs (29.38 %-87.13 %), while the abundance of potential host bacteria increased in EK2, raising potential transmission risk of MRGs. Furthermore, there was an elevated presence of bacteria associated with membrane transport as a response mechanism to HMs stress in EK1. Considering economic factors and environmental effects, EK treatment during the thermophilic stage was more effective in compost maturation, HMs passivation, as well as control of HMs resistance. This study provides an effective method to address HMs-related contamination with highly efficient maturation in swine manure composting.202540543370
8494140.8721Biochar effectively inhibits the horizontal transfer of antibiotic resistance genes via transformation. The rapid spread of antibiotic resistance genes (ARGs) has posed a risk to human health. Here, the effects of biochar (BC) on the horizontal transfer of ARG-carrying plasmids to Escherichia coli via transformation were systematically investigated. BC could significantly inhibit the transformation of ARGs and the inhibition degree increased with pyrolysis temperature. Rice straw-derived BC showed a stronger inhibitory effect on the transformation of ARGs than that of peanut shell-derived BC from the same pyrolysis temperature. The inhibitory effect of BC from low pyrolysis temperature (300 ℃) was mainly caused by BC dissolutions, while it was mainly attributed to BC solids for high pyrolysis temperature (700 ℃) BC. BC dissolutions could induce intramolecular condensation and even agglomeration of plasmids, hindering their transformation into competent bacteria. The cell membrane permeability was slightly decreased in BC dissolutions, which might also contribute to the inhibitory effect. Plasmid can be adsorbed by BC solids and the adsorption increased with BC pyrolysis temperature. Meanwhile, BC-adsorbed plasmid could hardly be transformed into E. coli. BC solids could also deactivate E. coli and thereby inhibit their uptake of ARGs. These findings provide a way using BC to limit the spread of ARGs in the environment.202234530277
8739150.8720LCT-EF258 with S17I Mutation in DprA Exhibits Horizontal Gene Transfer Deficiency After Spaceflight. BACKGROUND: Space is a special environment in which microgravity and cosmic rays are the primary factors that induce gene mutations of microorganisms. In our previous studies, a single point mutation in the gene dprA was found in an Enterococcus faecium strain of LCT-EF258 after spaceflight. DNA processing protein A (DprA) plays a prominent role in the horizontal transfer of genes among bacteria (such as Streptococcus pneumoniae, Helicobacter pylori, Bacillus subtilis, and Rhodobacter capsulatus). However, the function of DprA in E. faecium remains unknown. Furthermore, E. faecium could acquire antibiotic resistance through the horizontal transfer of antibiotic resistance genes, but it is unclear whether dprA mutants could affect this process in E. faecium.METHODS: In this study, we constructed a plasmid containing the vancomycin resistance gene vanA and then transferred the gene vanA into the dprA-mutant strain LCT-EF258 and the control strain LCT-EF90 using the electroporation technique. We then used Discovery Studio(TM) software to construct the 3D protein structure.RESULTS: The results showed that the horizontal transfer efficiency of the vancomycin resistance gene vanA in the dprA-mutant E. faecium decreased. And the hydrophobic core of the mutant DprA became stable and the binding affinity between the mutant DprA and ssDNA reduced.DISCUSSION: This study is an exploration of bacterial gene mutation after spaceflight. The dprA mutant could affect the ability of E. faecium to acquire exogenous resistance gene vanA, which offered us an interesting path to block the dissemination of resistance genes between strains.Yu Y, Chang D, Guo Q, Wang J, Liu C. LCT-EF258 with S171 mutation in DprA exhibits horizontal gene transfer deficiency after spaceflight. Aerosp Med Hum Perform. 2019; 90(2):116-122.201930670121
7848160.8719Simultaneous Removal of Antibiotic Resistant Bacteria, Antibiotic Resistance Genes, and Micropollutants by FeS(2)@GO-Based Heterogeneous Photo-Fenton Process. The co-occurrence of various chemical and biological contaminants of emerging concerns has hindered the application of water recycling. This study aims to develop a heterogeneous photo-Fenton treatment by fabricating nano pyrite (FeS(2)) on graphene oxide (FeS(2)@GO) to simultaneously remove antibiotic resistant bacteria (ARB), antibiotic resistance genes (ARGs), and micropollutants (MPs). A facile and solvothermal process was used to synthesize new pyrite-based composites. The GO coated layer forms a strong chemical bond with nano pyrite, which enables to prevent the oxidation and photocorrosion of pyrite and promote the transfer of charge carriers. Low reagent doses of FeS(2)@GO catalyst (0.25 mg/L) and H(2)O(2) (1.0 mM) were found to be efficient for removing 6-log of ARB and 7-log of extracellular ARG (e-ARG) after 30 and 7.5 min treatment, respectively, in synthetic wastewater. Bacterial regrowth was not observed even after a two-day incubation. Moreover, four recalcitrant MPs (sulfamethoxazole, carbamazepine, diclofenac, and mecoprop at an environmentally relevant concentration of 10 μg/L each) were completely removed after 10 min of treatment. The stable and recyclable composite generated more reactive species, including hydroxyl radicals (HO(•)), superoxide radicals (O(2)(• -)), singlet oxygen ((1)O(2)). These findings highlight that the synthesized FeS(2)@GO catalyst is a promising heterogeneous photo-Fenton catalyst for the removal of emerging contaminants.202235759741
7870170.8718Hierarchical Bi(2)O(2)CO(3) wrapped with modified graphene oxide for adsorption-enhanced photocatalytic inactivation of antibiotic resistant bacteria and resistance genes. There is growing pressure for wastewater treatment plants to mitigate the discharge of antibiotic resistant bacteria (ARB) and extracellular resistance genes (eARGs), which requires technological innovation. Here, hierarchical Bi(2)O(2)CO(3) microspheres were wrapped with nitrogen-doped, reduced graphene oxide (NRGO) for enhanced inactivation of multidrug-resistant E. coli NDM-1 and degradation of the plasmid-encoded ARG (bla(NDM-1)) in secondary effluent. The NRGO shell enhanced reactive oxygen species (ROS) generation (•OH and H(2)O(2)) by about three-fold, which was ascribed to broadened light absorption region (red-shifted up to 459 nm) and decreased electron-transfer time (from 55.3 to 19.8 ns). Wrapping enhanced E. coli adsorption near photocatalytic sites to minimize ROS scavenging by background constituents, which contributed to the NRGO-wrapped microspheres significantly outperforming commercial TiO(2) photocatalyst. ROS scavenger tests indicated that wrapping also changed the primary inactivation pathway, with photogenerated electron holes and surface-attached hydroxyl radicals becoming the predominant oxidizing species with wrapped microspheres, versus free ROS (e.g., •OH, H(2)O(2) and •O(2)(-)) for bare microspheres. Formation of resistance plasmid-composited microsphere complexes, primary due to the π-π stacking and hydrogen bonding between the shell and nucleotides, also minimized ROS scavenging and kept free plasmid concentrations below 10(2) copies/mL. As proof-of-concept, this work offers promising insight into the utilization of NRGO-wrapped microspheres for mitigating antibiotic resistance propagation in the environment.202032679343
7540180.8717Extended chloramination significantly enriched intracellular antibiotic resistance genes in drinking water treatment plants. Chloramination and chlorination are both strong barriers that prevent the transmission of potential pathogens to humans through drinking water. However, the comparative effects of chloramination and chlorination on the occurrence of antibiotic resistance genes (ARGs) in drinking water treatment plants (DWTPs) remain unknown. Herein, the antibiotic resistome in water before and after chloramination or chlorination was analyzed through metagenomic sequencing and then verified through quantitative real-time polymerase chain reaction (qPCR). After the treatment of 90 min, chloramination led to higher enrichment of the total relative abundance of intracellular ARGs (iARGs) in water than chlorination, whereas chlorination facilitated the release of more extracellular ARGs (eARGs) than chloramination. According to redundancy and Pearson's analyses, the total concentration of the observed iARGs in the finished water exhibited a strong positive correlation with ammonium nitrogen (NH(4)(+)-N) concentration, presenting a linear upward trend with an increase in the NH(4)(+)-N concentration. This indicated that NH(4)(+)-N is a crucial driving factor for iARG accumulation during chloramination. iARG enrichment ceases if the duration of chloramination is shortened to 40 min, suggesting that shortening the duration would be a better strategy for controlling iARG enrichment in drinking water. These findings emphasized the potential risk of antibiotic resistance after extended chloramination, shedding light on the control of transmission of antibiotic-resistant bacteria through water by optimizing disinfection procedures in DWTPs.202336739658
8721190.8717Chromium metabolism characteristics of coexpression of ChrA and ChrT gene. OBJECTIVE: Serratia sp. S2 is a wild strain with chromium resistance and reduction ability. Chromium(VI) metabolic-protein-coding gene ChrA and ChrT were cloned from Serratia sp. S2, and ligated with prokaryotic expression vectors pET-28a (+) and transformed into E. coli BL21 to construct ChrA, ChrT and ChrAT engineered bacteria. By studying the characteristics of Cr(VI) metabolism in engineered bacteria, the function and mechanism of the sole expression and coexpression of ChrA and ChrT genes were studied. METHODS: Using Serratia sp. S2 genome as template, ChrA and ChrT genes were amplified by PCR, and prokaryotic expression vectors was ligated to form the recombinant plasmid pET-28a (+)-ChrA, pET-28a (+)-ChrT and pET-28a (+)-ChrAT, and transformed into E. coli BL21 to construct ChrA, ChrT, ChrAT engineered bacteria. The growth curve, tolerance, and reduction of Cr(VI), the distribution of intracellular and extracellular Cr, activity of chromium reductase and intracellular oxidative stress in engineered bacteria were measured to explore the metabolic characteristics of Cr(VI) in ChrA, ChrT, ChrAT engineered bacteria. RESULTS: ChrA, ChrT and ChrAT engineered bacteria were successfully constructed by gene recombination technology. The tolerance to Cr(VI) was Serratia sp. S2 > ChrAT ≈ ChrA > ChrT > Control (P < 0.05), and the reduction ability to Cr(VI) was Serratia sp. S2 > ChrAT ≈ ChrT > ChrA (P < 0.05). The chromium distribution experiments confirmed that Cr(VI) and Cr(III) were the main valence states. Effect of electron donors on chromium reductase activity was NADPH > NADH > non-NAD(P)H (P < 0.05). The activity of chromium reductase increased significantly with NAD(P)H (P < 0.05). The Glutathione and NPSH (Non-protein Sulfhydryl) levels of ChrA, ChrAT engineered bacteria increased significantly (P < 0.05) under the condition of Cr(VI), but there was no significant difference in the indexes of ChrT engineered bacteria (P > 0.05). CONCLUSION: ChrAT engineered bacteria possesses resistance and reduction abilities of Cr(VI). ChrA protein endows the strain with the ability to resist Cr(VI). ChrT protein reduces Cr(VI) to Cr(III) by using NAD(P)H as electronic donor. The reduction process promotes the production of GSH, GSSG and NPSH to maintain the intracellular reduction state, which further improves the Cr(VI) tolerance and reduction ability of ChrAT engineered bacteria.202032768747