AGNPS - Word Related Documents




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848700.9758Mechanisms of nano zero-valent iron in enhancing dibenzofuran degradation by a Rhodococcus sp.: Trade-offs between ATP production and protection against reactive oxygen species. Nano zero-valent iron (nZVI) can enhance pollutants biodegradation, but it displays toxicity towards microorganisms. Gram-positive (G(+)) bacteria exhibit greater resistance to nZVI than Gram-negative bacteria. However, mechanisms of nZVI accelerating pollutants degradation by G(+) bacteria remain unclear. Herein, we explored effects of nZVI on a G(+) bacterium, Rhodococcus sp. strain p52, and mechanisms by which nZVI accelerates biodegradation of dibenzofuran, a typical polycyclic aromatic compound. Electron microscopy and energy dispersive spectroscopy analysis revealed that nZVI could penetrate cell membranes, which caused damage and growth inhibition. nZVI promoted dibenzofuran biodegradation at certain concentrations, while higher concentration functioned later due to the delayed reactive oxygen species (ROS) mitigation. Transcriptomic analysis revealed that cells adopted response mechanisms to handle the elevated ROS induced by nZVI. ATP production was enhanced by accelerated dibenzofuran degradation, providing energy for protein synthesis related to antioxidant stress and damage repair. Meanwhile, electron transport chain (ETC) was adjusted to mitigate ROS accumulation, which involved downregulating expression of ETC complex I-related genes, as well as upregulating expression of the genes for the ROS-scavenging cytochrome bd complex and ETC complex II. These findings revealed the mechanisms underlying nZVI-enhanced biodegradation by G(+) bacteria, offering insights into optimizing bioremediation strategies involving nZVI.202539549579
848610.9757Multidrug-resistant plasmid modulates ammonia oxidation efficiency in Nitrosomonas europaea through cyclic di-guanylate and acyl-homoserine lactones pathways. Antibiotic resistance genes present a major public health challenge and have potential implications for global biogeochemical cycles. However, their impacts on biological nitrogen removal systems remain poorly understood. In the ammonia-oxidizing bacteria Nitrosomonas europaea ATCC 19718 harboring the multidrug-resistant plasmid RP4, a significant decrease in ammonia oxidation efficiency was observed, accompanied by markedly elevated levels of cyclic di-guanylate (c-di-GMP) and acyl-homoserine lactones (AHLs), compared to plasmid-free controls. The results demonstrated that c-di-GMP facilitates the secretion of AHLs, while elevated levels of AHLs inhibit the ammonia oxidation efficiency of Nitrosomonas europaea ATCC 19718. These results revealed that RP4 plasmid significantly impaired ammonia oxidation efficiency through the c-di-GMP and AHLs pathways. Our findings indicate that the multidrug-resistant plasmid RP4 adversely affects the nitrogen metabolism of ammonia-oxidizing bacteria, potentially disrupting the nitrogen biogeochemical cycle and posing substantial ecological and environmental risks.202640945801
843620.9753NIR-Activated Hydrogel with Dual-Enhanced Antibiotic Effectiveness for Thorough Elimination of Antibiotic-Resistant Bacteria. Antibiotic resistance has become a critical health crisis globally. Traditional strategies using antibiotics can lead to drug-resistance, while inorganic antimicrobial agents can cause severe systemic toxicity. Here, we have developed a dual-antibiotic hydrogel delivery system (PDA-Ag@Levo/CMCS), which can achieve controlled release of clinical antibiotics levofloxacin (Levo) and classic nanoscale antibiotic silver nanoparticles (AgNPs), effectively eliminating drug-resistant P. aeruginosa. Benefiting from the photothermal (PTT) effect of polydopamine (PDA), the local high temperature generated by PDA-Ag@Levo/CMCS can quickly kill bacteria through continuous and responsive release of dual-antibiotics to restore sensitivity to ineffective antibiotics. Moreover, AgNPs could significantly improve the efficiency of traditional antibiotics by disrupting bacterial membranes and reducing their toxicity to healthy tissues. A clever combination of PTT and drug-combination therapy can effectively eliminate biofilms and drug-resistant bacteria. Mechanism studies have shown that PDA-Ag@Levo might eliminate drug-resistant P. aeruginosa by disrupting biofilm formation and protein synthesis, and inhibit the resistance mutation of P. aeruginosa by promoting the expression of related genes, such as rpoS, dinB, and mutS. Collectively, the synergistic effect of this dual-antibiotic hydrogel combined with PTT provides a creative strategy for eliminating drug-resistant bacteria in chronic infection wounds.202539760335
882430.9744Lactic acid bacteria modulate the CncC pathway to enhance resistance to β-cypermethrin in the oriental fruit fly. The gut microbiota of insects has been shown to regulate host detoxification enzymes. However, the potential regulatory mechanisms involved remain unknown. Here, we report that gut bacteria increase insecticide resistance by activating the cap "n" collar isoform-C (CncC) pathway through enzymatically generated reactive oxygen species (ROS) in Bactrocera dorsalis. We demonstrated that Enterococcus casseliflavus and Lactococcus lactis, two lactic acid-producing bacteria, increase the resistance of B. dorsalis to β-cypermethrin by regulating cytochrome P450 (P450) enzymes and α-glutathione S-transferase (GST) activities. These gut symbionts also induced the expression of CncC and muscle aponeurosis fibromatosis. BdCncC knockdown led to a decrease in resistance caused by gut bacteria. Ingestion of the ROS scavenger vitamin C in resistant strain affected the expression of BdCncC/BdKeap1/BdMafK, resulting in reduced P450 and GST activity. Furthermore, feeding with E. casseliflavus or L. lactis showed that BdNOX5 increased ROS production, and BdNOX5 knockdown affected the expression of the BdCncC/BdMafK pathway and detoxification genes. Moreover, lactic acid feeding activated the ROS-associated regulation of P450 and GST activity. Collectively, our findings indicate that symbiotic gut bacteria modulate intestinal detoxification pathways by affecting physiological biochemistry, thus providing new insights into the involvement of insect gut microbes in the development of insecticide resistance.202438618721
861440.9741Polystyrene nanoparticles induce biofilm formation in Pseudomonas aeruginosa. In recent years, micro/nanoplastics have garnered widespread attention due to their ecological risks. In this study, we investigated the effects of polystyrene nanoparticles (PS-NPs) of different sizes on the growth and biofilm formation of Pseudomonas aeruginosa PAO1. The results demonstrated that exposure to certain concentrations of PS-NPs significantly promoted bacterial biofilm formation. Meanwhile, we comprehensively revealed its mechanism whereby PS-NPs induced oxidative stress and altered bacterial membrane permeability by contacting or penetrating bacterial membranes. To counteract the stimulation by PS-NPs and reduce their toxicity, bacteria enhanced biofilm formation by upregulating the expression of biofilm-related genes, increasing EPS and virulence factors secretion, and enhancing bacterial motility through the participation of the quorum sensing (QS) system. Additionally, we also found that exposure to PS-NPs enhanced bacterial antibiotic resistance, posing a challenge to antimicrobial therapy. Our study reveals the toxic effects of nanoplastics and the defense mechanisms of bacteria, which has important implications for the risk assessment and management of environmental nanoplastics.202438442601
860950.9739Nano-biochar regulates phage-host interactions, reducing antibiotic resistance genes in vermicomposting systems. Biochar amendment reshapes microbial community dynamics in vermicomposting, but the mechanism of how phages respond to this anthropogenic intervention and regulate the dissemination of antibiotic resistance genes (ARGs) remains unclear. In this study, we used metagenomics, viromics, and laboratory validation to explore how nano-biochar affects phage-host interactions and ARGs dissemination in vermicomposting. Our results revealed distinct niche-specific phage life strategies. In vermicompost, lytic phages dominated and used a "kill-the-winner" strategy to suppress antibiotic-resistant bacteria (ARB). In contrast, lysogenic phages prevailed in the earthworm gut, adopting a "piggyback-the-winner" strategy that promoted ARGs transduction through mutualistic host interactions. Nano-biochar induced the conversion of lysogenic to lytic phages in the earthworm gut, while concurrently reducing the abundance of lysogenic phages and their encoded auxiliary metabolic genes carried by ARB. This shift disrupted phage-host mutualism and inhibited ARGs transmission via a "phage shunting" mechanism. In vitro validation with batch culture experiments further confirmed that lysogenic phages increased transduction of ARGs in the earthworm gut, while nano-biochar reduced the spread of ARGs by enhancing lysis infectivity. Our study constructs a mechanistic framework linking nano-biochar induced shifts in phage lifestyles that suppress ARG spread, offering insights into phage-host coadaptation and resistance mitigation strategies in organic waste treatment ecosystems.202540838886
861160.9739Silver nanoparticles facilitate phage-borne resistance gene transfer in planktonic and microplastic-attached bacteria. The spread of bacteriophage-borne antibiotic resistance genes (ARGs) poses a realistic threat to human health. Nanomaterials, as important emerging pollutants, have potential impacts on ARGs dissemination in aquatic environments. However, little is known about its role in transductive transfer of ARGs mediated by bacteriophage in the presence of microplastics. Therefore, this study comprehensively investigated the influence of silver nanoparticles (AgNPs) on the transfer of bacteriophage-encoded ARGs in planktonic Escherichia coli and microplastic-attached biofilm. AgNPs exposure facilitated the phage transduction in planktonic and microplastic-attached bacteria at ambient concentration of 0.1 mg/L. Biological binding mediated by phage-specific recognition, rather than physical aggregation conducted by hydrophilicity and ζ-potential, dominated the bacterial adhesion of AgNPs. The aggregated AgNPs in turn resulted in elevated oxidative stress and membrane destabilization, which promoted the bacteriophage infection to planktonic bacteria. AgNPs exposure could disrupt colanic acid biosynthesis and then reduce the thickness of biofilm on microplastics, contributing to the transfer of phage-encoded ARGs. Moreover, the roughness of microplastics also affected the performance of AgNPs on the transductive transfer of ARGs in biofilms. This study reveals the compound risks of nanomaterials and microplastics in phage-borne ARGs dissemination and highlights the complexity in various environmental scenarios.202438452675
843770.9732Tocopherol polyethylene glycol succinate-modified hollow silver nanoparticles for combating bacteria-resistance. Multiple drug resistance and the increase in the appearance of superbugs together with the exceedingly scant development of new potent antibiotic drugs pose an urgent global medical threat and imminent public security crisis. In the present study, we fabricated well-dispersed tocopherol polyethylene glycol succinate (TPGS)-capped silver nanoparticles (AgNPs) of about 10 nm in size. The hollow structure of the TPGS-capped AgNPs (TPGS/AgNPs) was confirmed and applied to load antibiotics. The TPGS/AgNPs proved to be able to cross the bacterial cell wall and penetrate into bacteria, thereby delivering more of the antibiotic to the interior of bacteria and thus enhancing the in vitro antibacterial effect of the antibiotic, even overcoming the drug-resistance in drug-resistant E. coli and Acinetobacter baumannii. It was found that the TPGS modification in the TPGS/AgNPs could decrease the activity of the efflux pumps AdeABC and AdeIJK in drug-resistant Acinetobacter baumannii via inhibiting the efflux pump genes adeB and adeJ, thus increasing the accumulation of the delivered antibiotic and overcoming the drug-resistance. Tigecycline delivered by TPGS/AgNPs could effectively antagonize drug-resistance in an acute peritonitis model mice, thereby increasing the survival rate and alleviating the inflammatory response. TPGS/AgNPs were developed as a novel and effective antibiotic delivery system and TPGS was demonstrated to have great potential as a pharmaceutical excipient for use in drug-resistant infection therapy.201930968093
849280.9732Promotion 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
861090.9732A systematic review of antibiotics and antibiotic resistance genes (ARGs) in mariculture wastewater: Antibiotics removal by microalgal-bacterial symbiotic system (MBSS), ARGs characterization on the metagenomic. Antibiotic residues in mariculture wastewater seriously affect the aquatic environment. Antibiotic Resistance Genes (ARGs) produced under antibiotic stress flow through the environment and eventually enter the human body, seriously affecting human health. Microalgal-bacterial symbiotic system (MBSS) can remove antibiotics from mariculture and reduce the flow of ARGs into the environment. This review encapsulates the present scenario of mariculture wastewater, the removal mechanism of MBSS for antibiotics, and the biomolecular information under metagenomic assay. When confronted with antibiotics, there was a notable augmentation in the extracellular polymeric substances (EPS) content within MBSS, along with a concurrent elevation in the proportion of protein (PN) constituents within the EPS, which limits the entry of antibiotics into the cellular interior. Quorum sensing stimulates the microorganisms to produce biological responses (DNA synthesis - for adhesion) through signaling. Oxidative stress promotes gene expression (coupling, conjugation) to enhance horizontal gene transfer (HGT) in MBSS. The microbial community under metagenomic detection is dominated by aerobic bacteria in the bacterial-microalgal system. Compared to aerobic bacteria, anaerobic bacteria had the significant advantage of decreasing the distribution of ARGs. Overall, MBSS exhibits remarkable efficacy in mitigating the challenges posed by antibiotics and resistant genes from mariculture wastewater.202438657817
8488100.9731Antihistamine drug loratadine at environmentally relevant concentrations promotes conjugative transfer of antibiotic resistance genes: Coeffect of oxidative stress and ion transport. Due to the widespread use of loratadine (LOR) as an antihistamine, it is widely distributed in the environment as an emerging contaminant. However, its impact on the dissemination of antibiotic resistance genes (ARGs) remains unclear. This study investigated the effect of LOR on the conjugative transfer of ARGs and elucidated the potential mechanisms through transcriptome analysis. The results showed that LOR significantly promoted the frequency of conjugative transfer up to 1.5- to 8.6-fold higher compared with the control group. Exposure to LOR increased reactive oxidative species (ROS) and intracellular Ca(2+) concentrations, leading to the upregulation of expression of genes related to transmembrane transport and SOS response. Meanwhile, it stimulated the increase of cell membrane permeability. Moreover, LOR exposure could enhance H(+) efflux in donor bacteria, resulting in the decrease of intracellular pH and the elevation of transmembrane potential, which could induce the increase of ion transport, thereby promoting plasmid efflux from the cell membrane. Based on this, we inferred that LOR can induce an increase in ROS level and intracellular Ca(2+) concentrations, and promoted the efflux of intracellular H(+). This, in turn, triggered the intensification of various ion transport processes on the cell membrane, thereby increasing membrane permeability and accelerating plasmid efflux. Ultimately, the coeffect of oxidative stress response and ion transport promoted conjugative transfer. This study demonstrated that LOR significantly promotes plasmid-mediated conjugative transfer of ARGs, providing novel insights into the mechanisms underlying this process.202539919578
8616110.9730Mechanisms of inhibition and recovery under multi-antibiotic stress in anammox: A critical review. With the escalating global concern for emerging pollutants, particularly antibiotics, microplastics, and nanomaterials, the potential disruption they pose to critical environmental processes like anaerobic ammonia oxidation (anammox) has become a pressing issue. The anammox process, which plays a crucial role in nitrogen removal from wastewater, is particularly sensitive to external pollutants. This paper endeavors to address this knowledge gap by providing a comprehensive overview of the inhibition mechanisms of multi-antibiotic on anaerobic ammonia-oxidizing bacteria, along with insights into their recovery processes. The paper dives deeply into the various ways antibiotics interact with anammox bacteria, focusing specifically on their interference with the bacteria's extracellular polymers (EPS) - crucial components that maintain the structural integrity and functionality of the cells. Additionally, it explores how anammox bacteria utilize quorum sensing (QS) mechanisms to regulate their community structure and respond to antibiotic stress. Moreover, the paper summarizes effective removal methods for these antibiotics from wastewater systems, which is crucial for mitigating their inhibitory effects on anammox bacteria. Finally, the paper offers valuable insights into how anammox communities can recuperate from multi-antibiotic stress. This includes strategies for reintroducing healthy bacteria, optimizing operational conditions, and using bioaugmentation techniques to enhance the resilience of anammox communities. In summary, this paper not only enriches our understanding of the complex interactions between antibiotics and anammox bacteria but also provides theoretical and practical guidance for the treatment of antibiotic pollution in sewage, ensuring the sustainability and effectiveness of wastewater treatment processes.202439366232
7926120.9730Microplastics Exacerbated Conjugative Transfer of Antibiotic Resistance Genes during Ultraviolet Disinfection: Highlighting Difference between Conventional and Biodegradable Ones. Microplastics (MPs) have been confirmed as a hotspot for antibiotic resistance genes (ARGs) in wastewater. However, the impact of MPs on the transfer of ARGs in wastewater treatment remains unclear. This study investigated the roles and mechanisms of conventional (polystyrene, PS) and biodegradable (polylactic acid, PLA) MPs in the conjugative transfer of ARGs during ultraviolet disinfection. The results showed that MPs significantly facilitated the conjugative transfer of ARGs compared with individual ultraviolet disinfection, and PSMPs exhibited higher facilitation than PLAMPs. The facilitation effects were attributed to light shielding and the production of reactive oxygen species (ROS) and nanoplastics from ultraviolet irradiation of MPs. The light shielding of MPs protected the bacteria and ARGs from ultraviolet inactivation. More importantly, ROS and nanoplastics generated from irradiated MPs induced intracellular oxidative stress on bacteria and further increased the cell membrane permeability and intercellular contact, ultimately enhancing the ARG exchange. The greater fragmentation of PSMPs than PLAMPs resulted in a higher intracellular oxidative stress and a stronger enhancement. This study highlights the concerns of conventional and biodegradable MPs associated with the transfer of ARGs during wastewater treatment, which provides new insights into the combined risks of MPs and ARGs in the environment.202539723446
7880130.9729The synergistic mechanism of β-lactam antibiotic removal between ammonia-oxidizing microorganisms and heterotrophs. Nitrifying system is an effective strategy to remove numerous antibiotics, however, the contribution of ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA) and heterotrophs for antibiotic removal are still unclear. In this study, the mechanism of β-lactam antibiotic (cefalexin, CFX) removal was studied in a nitrifying sludge system. Results showed that CFX was synergistically removed by AOB (Nitrosomonas, played a major role) and AOA (Candidatus_Nitrososphaera) through ammonia monooxygenase-mediated co-metabolism, and by heterotrophs (Pseudofulvimonas, Hydrogenophaga, RB41, Thauera, UTCFX1, Plasticicumulans, Phaeodactylibacter) through antibiotic resistance genes (ARGs)-encoded β-lactamases-mediated hydrolysis. Regardless of increased archaeal and heterotrophic CFX removal with the upregulation of amoA in AOA and ARGs, the system exhibited poorer CFX removal performance at 10 mg/L, mainly due to the inhibition of AOB. This study provides new reference for the important roles of heterotrophs and ARGs, opening the possibilities for the application of ARGs in antibiotic biodegradation.202336174754
8557140.9728Efficient inactivation of antibiotic resistant bacteria by iron-modified biochar and persulfate system: Potential for controlling antimicrobial resistance spread and mechanism insights. Antimicrobial resistance (AMR) is a critical global health threat, further intensified by the widespread dissemination of plasmid-encoded antibiotic resistance genes (ARGs), which poses a significant challenge to the "One Health" concept. Persulfate-based advanced oxidation processes (PS-AOPs) have emerged as effective disinfection methods, capable of degrading antibiotics, inactivating bacteria, and eliminating ARGs, whereas their efficacy towards blocking ARGs horizontal transfer remains elusive. This work constructed a series of Fe-modified soybean straw biochar (FeSSB) as persulfate (PS) activators through Fe-modification and temperature regulation. Among the tested systems, FeSSB800/PS achieved complete inactivation of antibiotic resistant bacteria (ARB) with a 7.04-log reduction within 60 min, outperforming others. FeSSB800, featuring the highest exposed-Fe(II) sites, most CO groups, and lowest charge transfer resistance, obtaining optimal PS activation and reactive species generation, which caused irreversible damage to ARB cells and significantly inhibited the transformation and conjugation efficiency of plasmid RP4. The inhibition mechanism is driven by the aggressive action of free radicals, which injure cell envelopes, induce oxidative stress, disrupt ATP synthesis, and alter intercellular adhesion. These findings underscore the potential of PS-AOPs as a promising strategy to mitigate AMR by simultaneously inactivating ARB and impeding ARGs dissemination.202540203758
7940150.9727Microplastics affect the ammonia oxidation performance of aerobic granular sludge and enrich the intracellular and extracellular antibiotic resistance genes. Microplastics (MPs) and antibiotic resistance genes (ARGs), as emerging pollutants, are frequently detected in wastewater treatment plants, and their threats to the environment have received extensive attentions. However, the effects of MPs on the nitrification of aerobic granular sludge (AGS) and the spread patterns of intracellular and extracellular ARGs (iARGs and eARGs) in AGS were still unknown. In this study, the responses of AGS to the exposure of 1, 10 and 100 mg/L of typical MPs (polyvinyl chloride (PVC), polyamide (PA), polystyrene (PS) and polyethylene (PE)) and tetracycline were focused on in 3 L nitrifying sequencing batch reactors. 10 mg/L MPs decreased the nitrification function, but nitrification could recover. Furthermore, MPs inhibited ammonia-oxidizing bacteria and enriched nitrite-oxidizing bacteria, leading partial nitrification to losing stability. PVC, PA and PS stimulated the secretion of extracellular polymeric substances and reactive oxygen species. PE had less negative effect on AGS than PVC, PA and PS. The abundances of iARGs and eARGs (tetW, tetE and intI1) increased significantly and the intracellular and extracellular microbial communities obviously shifted in AGS system under MPs stress. Potential pathogenic bacteria might be the common hosts of iARGs and eARGs in AGS system and were enriched in AGS and MPs biofilms.202133387747
6442160.9727A systematic review of antibiotic resistance driven by metal-based nanoparticles: Mechanisms and a call for risk mitigation. Elevations in antibiotic resistance genes (ARGs) are due not only to the antibiotic burden, but also to numerous environmental pressures (e.g., pesticides, metal ions, or psychotropic pharmaceuticals), which have led to an international public health emergency. Metal-based nanoparticles (MNPs) poison bacteria while propelling nanoresistance at ambient or sub-lethal concentrations, acting as a wide spectrum germicidal agent. Awareness of MNPs driven antibiotic resistance has created a surge of investigation into the molecule mechanisms of evolving and spreading environmental antibiotic resistome. Co-occurrence of MNPs resistance and antibiotic resistance emerge in environmental pathogens and benign microbes may entail a crucial outcome for human health. In this review we expound on the systematic mechanism of ARGs proliferation under the stress of MNPs, including reactive oxygen species (ROS) induced mutation, horizontal gene transfer (HGT) relevant genes regulation, nano-property, quorum sensing, and biofilm formation and highlighting on the momentous contribution of nanoparticle released ion. As antibiotic resistance pattern alteration is closely knit with the mediate activation of nanoparticle in water, soil, manure, or sludge habitats, we have proposed a virulence and evolution based antibiotic resistance risk assessment strategy for MNP contaminated areas and discussed practicable approaches that call for risk management in critical environmental compartments.202438220012
7925170.9726Effects comparison between the secondary nanoplastics released from biodegradable and conventional plastics on the transfer of antibiotic resistance genes between bacteria. Antibiotic resistance genes (ARGs) have caused widespread concern because of their potential harm to environmental safety and human health. As substitutes for conventional plastics, the toxic effects of short-term degradation products of biodegradable plastics (polylactic acid (PLA) and polyhydroxyalkanoates (PHA)) on bacteria and their impact on ARGs transfer were the focus of this study. After 60 days of degradation, more secondary nanoplastics were released from the biodegradable plastics PLA and PHA than that from the conventional plastics polystyrene (PS). All kinds of nanoplastics, no matter released from biodegradable plastics or conventional plastics, had no significant toxicity to bacteria. Nanoplastic particles from biodegradable plastics could significantly increase the transfer efficiency of ARGs. Although the amount of secondary nanoplastics produced by PHA microplastics was much higher than that of PLA, the transfer frequency after exposure to PLA was much higher, which may be due to the agglomeration of PHA nanoplastics caused by plastic instability in solution. After exposure to the 60 d PLA nanoplastics, the transfer frequency was the highest, which was approximately 28 times higher than that of control. The biodegradable nanoplastics significantly enhanced the expression of the outer membrane pore protein genes ompA and ompC, which could increase cell membrane permeability. The expression levels of trfAp and trbBp were increased by repressed major global regulatory genes korA, korB, and trbA, which eventually led to an increase in conjugative transfer frequency. This study provides important insights into the evaluation of the environmental and health risks caused by secondary nanoplastics released from biodegradable plastics.202336414161
8598180.9726Nonnutritive sweeteners can promote the dissemination of antibiotic resistance through conjugative gene transfer. Antimicrobial resistance (AMR) poses a worldwide threat to human health and biosecurity. The spread of antibiotic resistance genes (ARGs) via conjugative plasmid transfer is a major contributor to the evolution of this resistance. Although permitted as safe food additives, compounds such as saccharine, sucralose, aspartame, and acesulfame potassium that are commonly used as nonnutritive sweeteners have recently been associated with shifts in the gut microbiota similar to those caused by antibiotics. As antibiotics can promote the spread of antibiotic resistance genes (ARGs), we hypothesize that these nonnutritive sweeteners could have a similar effect. Here, we demonstrate for the first time that saccharine, sucralose, aspartame, and acesulfame potassium could promote plasmid-mediated conjugative transfer in three established conjugation models between the same and different phylogenetic strains. The real-time dynamic conjugation process was visualized at the single-cell level. Bacteria exposed to the tested compounds exhibited increased reactive oxygen species (ROS) production, the SOS response, and gene transfer. In addition, cell membrane permeability increased in both parental bacteria under exposure to the tested compounds. The expression of genes involved in ROS detoxification, the SOS response, and cell membrane permeability was significantly upregulated under sweetener treatment. In conclusion, exposure to nonnutritive sweeteners enhances conjugation in bacteria. Our findings provide insight into AMR spread and indicate the potential risk associated with the presence of nonnutritive sweeteners.202133589766
7928190.9726Insight into the responses of antibiotic resistance genes in microplastic biofilms to zinc oxide nanoparticles and zinc ions pressures in landfill leachate. Microplastic (MP) biofilms are hotspots of antibiotic resistance genes (ARGs) in landfill environment. MP biofilms in landfill leachate coexist with heavy metals and metallic nanoparticles (NPs) that considered to be the selective agents of ARGs. However, the effects of these selective pressures on ARGs in MP biofilms and their differences in MP-surrounding leachate have not been well understood. Herein, the changes of ARG abundances in MP biofilms and corresponding leachate under zinc oxide (ZnO) NPs and zinc ion (Zn(2+)) pressures were comparatively analyzed. The presence of ZnO NPs and Zn(2+) promoted the enrichment of ARGs in MP biofilms, and the enrichment was more pronounced in ZnO NPs groups. ZnO NPs and especially Zn(2+) mainly decreased the abundances of ARGs in leachate. The increase of integron abundances and reactive oxygen species production in MP biofilms implied the enhanced potential for horizontal transfer of ARGs under ZnO NPs and Zn(2+) pressures. Meanwhile, the co-occurrence pattern between ARGs and bacterial genera in MP biofilms with more diverse potential ARG hosts was more complex than in leachate, and the enrichment of ARG-hosting bacteria in MP biofilms under ZnO NPs and Zn(2+) pressures supported the enrichment of ARGs.202337480611