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871600.9383Organophosphorus mineralizing-Streptomyces species underpins uranate immobilization and phosphorus availability in uranium tailings. Phosphate-solubilizing bacteria (PSB) are important but often overlooked regulators of uranium (U) cycling in soil. However, the impact of PSB on uranate fixation coupled with the decomposition of recalcitrant phosphorus (P) in mining land remains poorly understood. Here, we combined gene amplicon sequencing, metagenome and metatranscriptome sequencing analysis and strain isolation to explore the effects of PSB on the stabilization of uranate and P availability in U mining areas. We found that the content of available phosphorus (AP), carbonate-U and Fe-Mn-U oxides in tailings was significantly (P < 0.05) higher than their adjacent soils. Also, organic phosphate mineralizing (PhoD) bacteria (e.g., Streptomyces) and inorganic phosphate solubilizing (gcd) bacteria (e.g., Rhodococcus) were enriched in tailings and soils, but only organic phosphate mineralizing-bacteria substantially contributed to the AP. Notably, most genes involved in organophosphorus mineralization and uranate resistance were widely present in tailings rather than soil. Comparative genomics analyses supported that organophosphorus mineralizing-Streptomyces species could increase soil AP content and immobilize U(VI) through organophosphorus mineralization (e.g., PhoD, ugpBAEC) and U resistance related genes (e.g., petA). We further demonstrated that the isolated Streptomyces sp. PSBY1 could enhance the U(VI) immobilization mediated by the NADH-dependent ubiquinol-cytochrome c reductase (petA) through decomposing organophosphorous compounds. This study advances our understanding of the roles of PSB in regulating the fixation of uranate and P availability in U tailings.202438908177
855610.9375Bubbles Expand the Dissemination of Antibiotic Resistance in the Aquatic Environment. Antibiotic resistance is a global health challenge, and the COVID-19 pandemic has amplified the urgency to understand its airborne transmission. The bursting of bubbles is a fundamental phenomenon in natural and industrial processes, with the potential to encapsulate or adsorb antibiotic-resistant bacteria (ARB). However, there is no evidence to date for bubble-mediated antibiotic resistance dissemination. Here, we show that bubbles can eject abundant bacteria to the air, form stable biofilms over the air-water interface, and provide opportunities for cell-cell contact that facilitates horizontal gene transfer at and over the air-liquid interface. The extracellular matrix (ECM) on bacteria can increase bubble attachment on biofilms, increase bubble lifetime, and, thus, produce abundant small droplets. We show through single-bubble probe atomic force microscopy and molecular dynamics simulations that hydrophobic interactions with polysaccharides control how the bubble interacts with the ECM. These results highlight the importance of bubbles and its physicochemical interaction with ECM in facilitating antibiotic resistance dissemination and fulfill the framework on antibiotic resistance dissemination.202337379503
873520.9372The Effect of Ice-Nucleation-Active Bacteria on Metabolic Regulation in Evergestis extimalis (Scopoli) (Lepidoptera: Pyralidae) Overwintering Larvae on the Qinghai-Tibet Plateau. Evergestis extimalis (Scopoli) is a significant pest of spring oilseed rape in the Qinghai-Tibet Plateau. It has developed resistance to many commonly used insecticides. Therefore, biopesticides should be used to replace the chemical pesticides in pest control. In this study, the effects of ice-nucleation-active (INA) microbes (Pseudomonas syringae 1.7277, P. syringae 1.3200, and Erwinia pyrifoliae 1.3333) on E. extimalis were evaluated. The supercooling points (SCP) were markedly increased due to the INA bacteria application when they were compared to those of the untreated samples. Specifically, the SCP of E. extimalis after its exposure to a high concentration of INA bacteria in February were -10.72 °C, -13.73 °C, and -14.04 °C. Our findings have demonstrated that the trehalase (Tre) genes were up-regulated by the application of the INA bacteria, thereby resulting in an increased trehalase activity. Overall, the INA bacteria could act as effective heterogeneous ice nuclei which could lower the hardiness of E. extimalis to the cold and then freeze them to death in an extremely cold winter. Therefore, the control of insect pests with INA bacteria goes without doubt, in theory.202236292857
855830.9362Mitigating the vertical migration and leaching risks of antibiotic resistance genes through insect fertilizer application. The leaching and vertical migration risks of antibiotic resistance genes (ARGs) from fertilized soil to groundwater poses a significant threat to ecological and public safety. Insect fertilizer, particularly black soldier fly organic fertilizer (BOF), renowned for its minimal antibiotic resistance, emerge as a promising alternative for sustainable agricultural fertilization. This study employs soil-column leaching experiments to evaluate the impact of BOF on the leaching behavior of ARGs. Our results reveal that BOF significantly reduces the leaching risks of ARGs by 22.1 %-49.3 % compared to control organic fertilizer (COF). Moreover, BOF promotes the leaching of beneficial Bacillus and, according to random forest analysis, is the most important factor in predicting ARG profiles (3.02 % increase in the MSE). Further network analysis and mantel tests suggest that enhanced nitrogen metabolism in BOF leachates could foster Bacillus biofilm formation, thereby countering antibiotic-resistant bacteria (ARB) and mitigating antibiotic resistance. In addition, linear regression analysis revealed that Bacillus biofilm-associated genes pgaD (biofilm PGA synthesis protein), slrR (biofilm formation regulator), and kpsC (capsular polysaccharide export protein) were identified as pivotal in the elimination of ARGs, which can serve as effective indicators for assessing antibiotic resistance in groundwater. Collectively, this study demonstrates that BOF as an environmentally friendly fertilizer could markedly reduce the vertical migration risks of ARGs and proposes Bacillus biofilm formation related genes as reliable indicators for monitoring antibiotic resistance in groundwater.202540086570
783340.9354Defect-Rich Cu(2)O Nanospheres as a Fenton-Like Catalyst for Cu(III) Generation: Enhanced Inactivation of Antibiotic-Resistant Bacteria and Genes. Cupryl species (Cu(III)) are promising oxidants for degrading recalcitrant organic contaminants and harmful microorganisms in water. In this study, defect-rich cuprous oxide (D-Cu(2)O) nanospheres (NSs) are introduced as a Fenton-like catalyst to generate Cu(III) for the inactivation of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs). D-Cu(2)O, in the presence of H(2)O(2), achieved inactivation efficiencies 3.2, 3.0, and 2.4 times higher than those of control Cu(2)O for ARB, extracellular ARGs (e-ARGs), and intracellular ARGs (i-ARGs), respectively. Experimental evidence from oxidant scavenging tests, Cu(III)-periodate complexation assays, electron paramagnetic resonance (EPR), and in situ Raman spectroscopy confirmed that D-Cu(2)O significantly enhanced Cu(III) generation when reacting with H(2)O(2) compared to control Cu(2)O. Density functional theory (DFT) calculations further revealed that unsaturated copper atoms in D-Cu(2)O enhance H(2)O(2) adsorption by improving the structural accessibility of adjacent oxygen atoms. This facilitates electron transfer processes and promotes subsequent Cu(III) generation. The D-Cu(2)O/H(2)O(2) system demonstrated excellent reusability, maintaining a 4-log reduction of ARB over five cycles, and proved effective across various water matrices and microbial species. These findings highlight the potential of the D-Cu(2)O/H(2)O(2) system, driven by defect engineering, as a robust platform for enhancing water safety and advancing sustainable disinfection technologies.202540795282
849150.9352Hormesis-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
787060.9350Hierarchical 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
580270.9348Dissecting vancomycin-intermediate resistance in staphylococcus aureus using genome-wide association. Vancomycin-intermediate Staphylococcus aureus (VISA) is currently defined as having minimal inhibitory concentration (MIC) of 4-8 µg/ml. VISA evolves through changes in multiple genetic loci with at least 16 candidate genes identified in clinical and in vitro-selected VISA strains. We report a whole-genome comparative analysis of 49 vancomycin-sensitive S. aureus and 26 VISA strains. Resistance to vancomycin was determined by broth microdilution, Etest, and population analysis profile-area under the curve (PAP-AUC). Genome-wide association studies (GWAS) of 55,977 single-nucleotide polymorphisms identified in one or more strains found one highly significant association (P = 8.78 E-08) between a nonsynonymous mutation at codon 481 (H481) of the rpoB gene and increased vancomycin MIC. Additionally, we used a database of public S. aureus genome sequences to identify rare mutations in candidate genes associated with VISA. On the basis of these data, we proposed a preliminary model called ECM+RMCG for the VISA phenotype as a benchmark for future efforts. The model predicted VISA based on the presence of a rare mutation in a set of candidate genes (walKR, vraSR, graSR, and agrA) and/or three previously experimentally verified mutations (including the rpoB H481 locus) with an accuracy of 81% and a sensitivity of 73%. Further, the level of resistance measured by both Etest and PAP-AUC regressed positively with the number of mutations present in a strain. This study demonstrated 1) the power of GWAS for identifying common genetic variants associated with antibiotic resistance in bacteria and 2) that rare mutations in candidate gene, identified using large genomic data sets, can also be associated with resistance phenotypes.201424787619
786980.9346Nano-CeO(2) activates physical and chemical defenses of garlic (Allium sativum L.) for reducing antibiotic resistance genes in plant endosphere. The transmission of manure- and wastewater-borne antibiotic-resistant bacteria (ARB) to plants contributes to the proliferation of antimicrobial resistance in agriculture, necessitating effective strategies for preventing the spread of antibiotic resistance genes (ARGs) from ARB in the environment to humans. Nanomaterials are potential candidates for efficiently controlling the dissemination of ARGs. The present study investigated the abundance of ARGs in hydroponically grown garlic (Allium sativum L.) following nano-CeO(2) (nCeO(2)) application. Specifically, root exposure to nCeO(2) (1, 2.5, 5, 10 mg L(-1), 18 days) reduced ARG abundance in the endosphere of bulbs and leaves. The accumulation of ARGs (cat, tet, and aph(3')-Ia) in garlic bulbs decreased by 24.2-32.5 % after nCeO(2) exposure at 10 mg L(-1). Notably, the lignification extent of garlic stem-disc was enhanced by 10 mg L(-1) nCeO(2), thereby accelerating the formation of an apoplastic barrier to impede the upward transfer of ARG-harboring bacteria to garlic bulbs. Besides, nCeO(2) upregulated the gene expression related to alliin biosynthesis and increased allicin content by 15.9-16.2 %, promoting a potent antimicrobial defense for reducing ARG-harboring bacteria. The potential exposure risks associated with ARGs and Ce were evaluated according to the estimated daily intake (EDI). The EDI of ARGs exhibited a decrease exceeding 95 %, while the EDI of Ce remained below the estimated oral reference dose. Consequently, through stimulating physical and chemical defenses, nCeO(2) contributed to a reduced EDI of ARGs and Ce, highlighting its potential for controlling ARGs in plant endosphere within the framework of nano-enabled agrotechnology.202438570269
848690.9344Multidrug-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
8488100.9344Antihistamine 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
7828110.9344Simultaneous 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
7879120.9344Multidrug-resistant plasmid RP4 increases NO and N(2)O yields via the electron transport system in Nitrosomonas europaea ammonia oxidation. Antibiotic resistance genes (ARGs) have recently become an important public health problem and therefore several studies have characterized ARG composition and distribution. However, few studies have assessed their impact on important functional microorganisms in the environment. Therefore, our study sought to investigate the mechanisms through which multidrug-resistant plasmid RP4 affected the ammonia oxidation capacity of ammonia-oxidizing bacteria, which play a key role in the nitrogen cycle. The ammonia oxidation capacity of N. europaea ATCC25978 (RP4) was significantly inhibited, and NO and N(2)O were produced instead of nitrite. Our findings demonstrated that the decrease in electrons from NH(2)OH decreased the ammonia monooxygenase (AMO) activity, leading to a decrease in ammonia consumption. In the ammonia oxidation process, N. europaea ATCC25978 (RP4) exhibited ATP and NADH accumulation. The corresponding mechanism was the overactivation of Complex Ⅰ, ATPase, and the TCA cycle by the RP4 plasmid. The genes encoding TCA cycle enzymes related to energy generation, including gltA, icd, sucD, and NE0773, were upregulated in N. europaea ATCC25978 (RP4). These results demonstrate the ecological risks of ARGs, including the inhibition of the ammonia oxidation process and an increased production of greenhouse gases such as NO and N(2)O.202337421866
8492130.9343Promotion 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
7855140.9342Combat 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
7851150.9341Breaking antibiotic resistance: Sunlight-powered calcium peroxide for dual bactericidal and genetic elimination. Antibiotic-resistant bacteria (ARB) and associated antibiotic resistance genes (ARGs) have emerged as critical waterborne contaminants, posing serious public health risks. This study proposes a disinfection strategy through sunlight powered calcium peroxide (CaO(2)) treatment that simultaneously inactivates ARB and degrades ARGs in aquatic environments. Solar irradiation combined with CaO(2) (3.0 mM) activates dual mechanisms: alkaline-driven microbial inactivation (pH increase from 6.4 to 8.2 within 30 min) and ROS-mediated oxidative damage (ROS: (•)OH, H(2)O(2), (1)O(2) and O(2)(•-)), achieving complete 5-log inactivation of tetracycline and sulfonamides-resistant E. coli (TSRE). ARGs (tetA and sul2) showed 70-80 % reduction in absolute abundance, although the log removal did not exceed 1-log. Compared to sunlight alone, the addition of CaO(2) significantly enhanced disinfection efficiency. Alkaline and ROS-induced oxidative stress caused membrane lipid breakdown, protein denaturation, and suppression of antioxidant enzymes, along with DNA damage, lipid peroxidation, and enzyme inactivation. These effects increased membrane permeability, impaired bacterial recovery by downregulating DNA repair genes, and disrupted cellular integrity, ultimately limiting ARGs persistence. These findings highlight the synergistic effect of alkaline and oxidative stress in effectively inactivating ARB and degrading ARGs, positioning sunlight powered CaO(2) as a promising, highly efficient disinfection strategy for environmental water treatment.202540876436
551160.9339virK and mig-14 constitute a PhoP-dependent operon and contribute to the intracellular survival and polymyxin B resistance of Salmonella Typhi. In bacteria, adjacent and functionally similar genes are typically transcribed as operons. The virulence genes virK and mig-14 are acquired through horizontal gene transfer in Salmonella. Previous studies have reported that these two genes have similar functions in terms of bacterial survival within macrophages and resistance to antimicrobial peptides. Nevertheless, the specific expression characteristics of the two genes remain unclear. This study revealed that virK and mig-14 were transcribed as a single operon in Salmonella Typhi. The virK-mig-14 operon was found to be activated under conditions of early hyperosmotic stress and polymyxin B stimulation, and its activation was dependent on the presence of the regulator PhoP. The luminescence assay demonstrated that the activity of the virK promoter was markedly elevated in an environment conducive to operon activation, whereas the mig-14 promoter exhibited no discernible change. This suggests that mig-14 is predominantly transcribed as a component of the operon. In the PhoP activation environment, which has a mildly acidic pH, low Mg(2+) levels, and intracellular macrophages, the virK-mig-14 operon exhibited significant activation. The absence of virK or mig-14 resulted in the impaired survival of Salmonella Typhi within macrophages and decreased its tolerance to polymyxin B. Collectively, this study shows that virK and mig-14 constitute an operon whose activation depends on PhoP and that it promotes S. Typhi's survival in macrophages and resistance to polymyxin B.202540345346
7864170.9339Simultaneous removal of antibiotics and antibiotic resistant genes using a CeO(2)@CNT electrochemical membrane-NaClO system. The simultaneous removal of antibiotic and antibiotic resistance genes (ARGs) are important to inhibit the spread of antibiotic resistance. In this study, a coupled treatment system was developed using a CeO(2) modified carbon nanotube electrochemical membrane and NaClO (denoted as CeO(2)@CNT-NaClO) to treat simulated water samples containing antibiotics and antibiotic-resistant bacteria (ARB). As the mass ratio of CeO(2) to CNT was 5:7 and the current density was 2.0 mA/cm(2), the CeO(2)@CNT-NaClO system removed 99% of sulfamethoxazole, 4.6 log sul1 genes, and 4.7 log intI1 genes from the sulfonamide-resistance water samples, and removed 98% of tetracycline, 2.0 log tetA genes, and 2.6 log intI1 genes of the tetracycline-resistance water samples. The outstanding performance of the CeO(2)@CNT-NaClO system for simultaneously removing antibiotic and ARGs was mainly ascribed to the generation of multiple reactive species, including •OH, •ClO, •O(2)(-) and (1)O(2). Antibiotics can undergo efficient degradation by •OH. However, the reaction between •OH and antibiotics reduces the availability of •OH to permeate into the cells and react with DNA. Nevertheless, the presence of •OH enhancd the effects of •ClO, •O(2)(-), and (1)O on ARG degradation. Through the coupled action of •OH, •ClO, •O(2)(-), and (1)O(2), the cell membranes of ARB experience severe damage, resulting in an increase in intracellular reactive oxygen species (ROS) and a decrease in superoxide dismutase (SOD) activity. Consequently, this coordinated mechanism leads to superior removal of ARGs.202337429382
7860180.9339Enhanced removal of antibiotic-resistant bacteria and resistance genes by three-dimensional electrochemical process using MgFe(2)O(4)-loaded biochar as both particle electrode and catalyst for peroxymonosulfate activation. In this study, MgFe(2)O(4)-loaded biochar (MFBC) was used as a three-dimensional particle electrode to active peroxymonosulfate (EC/MFBC/PMS) for the removal of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs). The results demonstrated that, under the conditions of 1.0 mM PMS concentration, 0.4 g/L material dosage, 5 V voltage intensity, and MFBC preparation temperature of 600 °C, the EC/MFBC600/PMS system achieved complete inactivation of E. coli DH5α within 5 min and the intracellular sul1 was reduced by 81.5 % after 30 min of the treatment. Compared to EC and PMS alone treatments, the conjugation transfer frequency of sul1 rapidly declined by 92.9 % within 2 min. The cell membrane, proteins, lipids, as well as intracellular and extracellular ARGs in E. coli DH5α were severely damaged by free radicals in solution and intracellular reactive oxygen species (ROS). Furthermore, up-regulation was observed in genes associated with oxidative stress, SOS response and cell membrane permeability in E. coli DH5α, however, no significant changes were observed in functional genes related to gene conjugation and transfer mechanisms. This study would contribute to the underlying of PMS activation by three-dimensional particle electrode, and provide novel insights into the mechanism of ARB inactivation and ARGs degradation under PMS advanced oxidation treatment.202439197284
508190.9339Insights into the chaotropic tolerance of the desert cyanobacterium Chroococcidiopsis sp. 029 (Chroococcidiopsales, Cyanobacteria). The mechanism of perchlorate resistance of the desert cyanobacterium Chroococcidiopsis sp. CCMEE 029 was investigated by assessing whether the pathways associated with its desiccation tolerance might play a role against the destabilizing effects of this chaotropic agent. During 3 weeks of growth in the presence of 2.4 mM perchlorate, an upregulation of trehalose and sucrose biosynthetic pathways was detected. This suggested that in response to the water stress triggered by perchlorate salts, these two compatible solutes play a role in the stabilization of macromolecules and membranes as they do in response to dehydration. During the perchlorate exposure, the production of oxidizing species was observed by using an oxidant-sensing fluorochrome and determining the expression of the antioxidant defense genes, namely superoxide dismutases and catalases, while the presence of oxidative DNA damage was highlighted by the over-expression of genes of the base excision repair. The involvement of desiccation-tolerance mechanisms in the perchlorate resistance of this desert cyanobacterium is interesting since, so far, chaotropic-tolerant bacteria have been identified among halophiles. Hence, it is anticipated that desert microorganisms might possess an unrevealed capability of adapting to perchlorate concentrations exceeding those naturally occurring in dry environments. Furthermore, in the endeavor of supporting future human outposts on Mars, the identified mechanisms might contribute to enhance the perchlorate resistance of microorganisms relevant for biologically driven utilization of the perchlorate-rich soil of the red planet.202438156502