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811100.9869Effect of alkaline-thermal pretreatment on biodegradable plastics degradation and dissemination of antibiotic resistance genes in co-compost system. Biodegradable plastics (BDPs) are an eco-friendly alternative to traditional plastics in organic waste, but their microbial degradation and impact on antibiotic resistance genes (ARGs) transmission during co-composting remain poorly understood. This study examines how alkaline-thermal pretreatment enhances BDPs degradation and influences the fate of ARGs and mobile genetic elements (MGEs) in co-composting. Pretreatment with 0.1 mol/L NaOH at 100℃ for 40 minutes increased the surface roughness and hydrophilicity of BDPs while reducing their molecular weight and thermal stability. Incorporating pretreated BDPs film (8 g/kg-TS) into the compost reduced the molecular weight of the BDPs by 59.70 % during the maturation stage, facilitating compost heating and prolonging the thermophilic stage. However, incomplete degradation of BDPs releases numerous smaller-sized microplastics, which can act as carriers for microorganisms, facilitating the dissemination of ARGs across environments and posing significant ecological and public health risks. Metagenomic analysis revealed that pretreatment enriched plastic-degrading bacteria, such as Thermobifida fusca, on BDPs surfaces and accelerated microbial plastic degradation during the thermophilic stage, but also increased ARGs abundance. Although pretreatment significantly reduced MGEs abundance (tnpA, IS19), the risk of ARGs dissemination remained. Three plastic-degrading bacteria (Pigmentiphaga sp002188465, Bacillus clausii, and Bacillus altitudinis) were identified as ARGs hosts, underscoring the need to address the risk of horizontal gene transfer of ARGs associated with pretreatment in organic waste management.202539970645
788710.9867Double-edged sword effects of sulfate reduction process in sulfur autotrophic denitrification system: Accelerating nitrogen removal and promoting antibiotic resistance genes spread. This study proposed the double-edged sword effects of sulfate reduction process on nitrogen removal and antibiotic resistance genes (ARGs) transmission in sulfur autotrophic denitrification system. Excitation-emission matrix-parallel factor analysis identified the protein-like fraction in soluble microbial products as main endogenous organic matter driving the sulfate reduction process. The resultant sulfide tended to serve as bacterial modulators, augmenting electron transfer processes and mitigating oxidative stress, thereby enhancing sulfur oxidizing bacteria (SOB) activity, rather than extra electron donors. The cooperation between SOB and heterotroph (sulfate reducing bacteria (SRB) and heterotrophic denitrification bacteria (HDB)) were responsible for advanced nitrogen removal, facilitated by multiple metabolic pathways including denitrification, sulfur oxidation, and sulfate reduction. However, SRB and HDB were potential ARGs hosts and assimilatory sulfate reduction pathway positively contributed to ARGs spread. Overall, the sulfate reduction process in sulfur autotrophic denitrification system boosted nitrogen removal process, but also increased the risk of ARGs transmission.202439122125
789320.9866Removal of ofloxacin and inhibition of antibiotic resistance gene spread during the aerobic biofilm treatment of rural domestic sewage through the micro-nano aeration technology. Micro-nano aeration (MNA) has great potential for emerging contaminant removal. However, the mechanism of antibiotic removal and antibiotic resistance gene (ARG) spread, and the impact of the different aeration conditions remain unclear. This study investigated the adsorption and biodegradation of ofloxacin (OFL) and the spread of ARGs in aerobic biofilm systems under MNA and conventional aeration (CVA) conditions. Results showed that the MNA increased OFL removal by 17.27 %-40.54 % and decreased total ARG abundance by 36.37 %-54.98 %, compared with CVA. MNA-induced biofilm rough morphology, high zeta potential, and reduced extracellular polymeric substance (EPS) secretion enhanced OFL adsorption. High dissolved oxygen and temperature, induced by MNA-enriched aerobic bacteria and their carrying OFL-degrading genes, enhanced OFL biodegradation. MNA inhibited the enrichment of ARG host bacteria, which acquired ARGs possibly via horizontal gene transfer (HGT). Functional profiles involved in the HGT process, including reactive oxygen species production, membrane permeability, mobile genetic elements (MGEs), adenosine triphosphate synthesis, and EPS secretion, were down-regulated by MNA, inhibiting ARG spread. Partial least-squares path modeling revealed that MGEs might be the main factor inhibiting ARG spread. This study provides insights into the mechanisms by which MNA enhances antibiotic removal and inhibits ARG spread in aerobic biofilm systems.202539733752
860930.9865Nano-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
848740.9864Mechanisms 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
785150.9864Breaking 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
787560.9864Phenacetin enhanced the inorganic nitrogen removal performance of anammox bacteria naturally in-situ enriched system. Among the earliest synthetic antipyretic drugs, phenacetin (PNCT) could be used as the novel partial nitrification (PN) inhibitor to effectively inhibit nitrite-oxidizing bacteria (NOB). In practical application, the rapidly starting of PN could provide stable source of nitrite for anaerobic ammonium oxidation (anammox) process. However, impact of PNCT on anaerobic ammonia oxidizing bacteria (AnAOB) and its underlying mechanisms were not clear. In this research, totally 14 times of PNCT aerobic soaking treatment were performed in the AnAOB naturally enrichment system to improve total inorganic nitrogen removal efficiency (TINRE). After once of PNCT treatment, TINRE rose from 61.89 % to 79.93 %. After 14 times of PNCT treatment, NOB Nitrospira relative abundance decreased from 9.82 % to 0.71 %, though Candidatus Brocadia relative abundance also declined, it might gradually adjust to PNCT by converting the leading oligotype species. The activity and relative abundances of NOB were reduced by PNCT via decreasing the abundances of genes amoA and nxrB, enzymes NxrA and NxrB. Moreover, Candidatus Jettenia and Ca. Brocadia might be the potential host of qacH-01 and they played the crucial role in the shaping profile of antibiotic resistance genes (ARGs). The explosive propagation or transmission of ARGs might not take place after PNCT treatment.202439566627
787370.9864Wheat straw pyrochar more efficiently decreased enantioselective uptake of dinotefuran by lettuce and dissemination of antibiotic resistance genes than hydrochar in an agricultural soil. Remediation of soils pollution caused by dinotefuran, a chiral pesticide, is indispensable for ensuring human food security. In comparison with pyrochar, the effect of hydrochar on enantioselective fate of dinotefuran, and antibiotic resistance genes (ARGs) profiles in the contaminated soils remain poorly understood. Therefore, wheat straw hydrochar (SHC) and pyrochar (SPC) were prepared at 220 and 500 °C, respectively, to investigate their effects and underlying mechanisms on enantioselective fate of dinotefuran enantiomers and metabolites, and soil ARG abundance in soil-plant ecosystems using a 30-day pot experiment planted with lettuce. SPC showed a greater reduction effect on the accumulation of R- and S-dinotefuran and metabolites in lettuce shoots than SHC. This was mainly resulted from the lowered soil bioavailability of R- and S-dinotefuran due to adsorption/immobilization by chars, together with the char-enhanced pesticide-degrading bacteria resulted from increased soil pH and organic matter content. Both SPC and SHC efficiently reduced ARG levels in soils, owing to lowered abundance of ARG-carrying bacteria and declined horizontal gene transfer induced by decreased dinotefuran bioavailability. The above results provide new insights for optimizing char-based sustainable technologies to mitigate pollution of dinotefuran and spread of ARGs in agroecosystems.202336996986
790880.9863DNA-based stable isotope probing deciphered the active denitrifying bacteria and triclosan-degrading bacteria participating in granule-based partial denitrification process under triclosan pressure. Granule-based partial denitrification (PD) is a technology that can supply stable nitrite for applying anaerobic ammonia oxidation in wastewater treatment, and triclosan (TCS) is a frequently detected antibacterial agent in wastewater treatment plants, therefore it is possible that TCS could enter into wastewater that is treated using PD technology. However, the active microorganisms responsible for PD and TCS removing in granule-based PD system have not been clearly identified and it is currently not clear how TCS affects the PD process. In this study, the impacts of TCS on PD performance, PD microbial community, antibiotic resistance genes (ARGs), active PD bacteria and TCS-degrading bacteria in a granule-based PD system were investigated. 3 mg/L TCS had adverse influence on PD process, but PD system could recover gradually after inhibiting of 10 days. After a period of domestication, PD granular sludge could achieve 10.66% of TCS degradation efficiency and 43.62% of TCS adsorption efficiency. Microbes might increase their resistance to TCS by increasing the secretion of extracellular polymeric substances, and the secretion of protein might play a more pivotal role than the secretion of polysaccharides in resisting TCS. The short-term shock of TCS might cause the propagation of acrA-03, while the long-term operation of TCS could propagate fabK and intI1. DNA stable isotope probing assay indicated that Thauera was active PD bacteria and TCS-degrading bacteria in the granule-based PD system, and it could contribute to nitrite accumulation and TCS degradation, simultaneously.202234979468
854890.9863Persulfate salts to combat bacterial resistance in the environment through antibiotic degradation and biofilm disruption. Antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) have become a critical topic among researchers because of the excessive use of antibiotics in human and animal health care. Globally, it poses a serious threat to human health and the environment. Antibiotics are often poorly metabolized, with 30-90 % excreted into the environment, contaminating aquatic and ground ecosystems, and fostering resistance. Advanced oxidation processes (AOPs), particularly sulfate radical-based AOPs (SR-AOPs), offer promising solutions for degrading antibiotics and resistant biofilms. Persulfate (PS) and Peroxymonosulfate (PMS) are key oxidants in these processes, generating sulfate and hydroxyl radicals when activated by heat, UV light, or transition metals. PS with a redox potential of E°=2.01 V is an affordable and effective oxidant. However, PS requires activation for the degradation of contaminants. PMS is stable across a broad pH range and produces both sulfate and hydroxyl radicals, allowing it to function independently without activation. Thus, PMS serving as a versatile agent for environmental treatment. This review broadly describes the degradation mechanisms of different classes of antibiotics and biofilms. Despite these promising developments, SR-AOPs still face challenges in managing complex wastewater systems, which often contain multiple pollutants. Moreover, gaps remain in understanding of the toxicity of reaction intermediates and in optimizing the large-scale application of these processes. Future research should focus on the in-situ generation of sulfate radicals, combining different activation methods to enhance degradation efficiency, and developing sustainable and cost-effective approaches for large-scale wastewater treatment.202540532556
7853100.9862Natural pyrite and ascorbic acid co-enhance periodate activation for inactivation of antibiotic resistant bacteria and inhibition of resistance genes transmission: A green disinfection process dominated by singlet oxygen. The transmission of antibiotic resistance genes (ARGs) and the propagation of antibiotic resistant bacteria (ARB) threaten public health security and human health, and greener and more efficient disinfection technologies are expected to be discovered for wastewater treatment. In this study, natural pyrite and ascorbic acid (AA) were proposed as environmental-friendly activator and reductant for periodate (PI) activation to inactivate ARB. The disinfection treatment of PI/pyrite/AA system could inactivate 5.62 log ARB within 30 min, and the lower pH and higher PI and natural pyrite dosage could further boost the disinfection efficiency. The (1)O(2) and SO(4)(•-) were demonstrated to be crucial for the inactivation of ARB in PI/pyrite/AA system. The disinfection process destroyed the morphological structure of ARB, inducing oxidative stress and stimulating the antioxidant system. The PI/pyrite/AA system effectively reduced the intracellular and extracellular DNA concentration and ARGs abundance, inhibiting the propagation of ARGs. The presence of AA facilitated the activation of PI with natural pyrite and significantly increased the concentration of Fe(2+) in solution. The reusability of natural pyrite, the safety of the disinfection by-products and the inhibition of ARB regeneration indicated the application potential of PI/pyrite/AA system in wastewater disinfection.202439038380
8615110.9862How anammox responds to the emerging contaminants: Status and mechanisms. Numerous researches have been carried out to study the effects of emerging contaminants in wastewater, such as antibiotics, nanomaterials, heavy metals, and microplastics, on the anammox process. However, they are fragmented and difficult to provide a comprehensive understanding of their effects on reactor performance and the metabolic mechanisms in anammox bacteria. Therefore, this paper overviews the effects on anammox processes by the introduced emerging contaminants in the past years to fulfill such knowledge gaps that affect our perception of the inhibitory mechanisms and limit the optimization of the anammox process. In detail, their effects on anammox processes from the aspects of reactor performance, microbial community, antibiotic resistance genes (ARGs), and functional genes related to anammox and nitrogen transformation in anammox consortia are summarized. Furthermore, the metabolic mechanisms causing the cell death of anammox bacteria, such as induction of reactive oxygen species, limitation of substrates diffusion, and membrane binding are proposed. By offering this review, the remaining research gaps are identified, and the potential metabolic mechanisms in anammox consortia are highlighted.202134087646
8557120.9861Efficient 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
8619130.9861Bioavailability of pollutants and chemotaxis. The exposure of bacteria to pollutants induces frequently chemoattraction or chemorepellent reactions. Recent research suggests that the capacity to degrade a toxic compound has co-evolved in some bacteria with the capacity to chemotactically react to it. There is an increasing amount of data which show that chemoattraction to biodegradable pollutants increases their bioavailability which translates into an enhancement of the biodegradation rate. Pollutant chemoreceptors so far identified are encoded on degradation or resistance plasmids. Genetic engineering of bacteria, such as the transfer of chemoreceptor genes, offers thus the possibility to optimize biodegradation processes.201322981870
8159140.9860Quaternary Ammonium Salts: Insights into Synthesis and New Directions in Antibacterial Applications. The overuse of antibiotics has led to the emergence of a large number of antibiotic-resistant genes in bacteria, and increasing evidence indicates that a fungicide with an antibacterial mechanism different from that of antibiotics is needed. Quaternary ammonium salts (QASs) are a biparental substance with good antibacterial properties that kills bacteria through simple electrostatic adsorption and insertion into cell membranes/altering of cell membrane permeability. Therefore, the probability of bacteria developing drug resistance is greatly reduced. In this review, we focus on the synthesis and application of single-chain QASs, double-chain QASs, heterocyclic QASs, and gemini QASs (GQASs). Some possible structure-function relationships of QASs are also summarized. As such, we hope this review will provide insight for researchers to explore more applications of QASs in the field of antimicrobials with the aim of developing systems for clinical applications.202336748912
7874150.9860Phenacetin promoted the rapid start-up and stable maintenance of partial nitrification: Responses of nitrifiers and antibiotic resistance genes. Phenacetin (PNCT) belongs to one of the earliest synthetic antipyretics. However, impact of PNCT on nitrifying microorganisms in wastewater treatment plants and its potential microbial mechanism was still unclear. In this study, PN could be initiated within six days by PNCT anaerobic soaking treatment (8 mg/L). In order to improve the stable performance of PN, 21 times of PNCT aerobic soaking treatment every three days was conducted and PN was stabilized for 191 days. After PN was damaged, ten times of PNCT aerobic soaking treatment every three days was conducted and PN was recovered after once soaking, maintained over 88 days. Ammonia oxidizing bacteria might change the dominant oligotype to gradually adjust to PNCT, and the increase of abundance and activity of Nitrosomonas promoted the initiation of PN. For nitrite-oxidizing bacteria (NOB), the increase of Candidatus Nitrotoga and Nitrospira destroyed PN, but PN could be recovered after once aerobic soaking illustrating NOB was not resistant to PNCT. KEGG and COG analysis suggested PNCT might disrupt rTCA cycle of Nitrospira, resulting in the decrease of relative abundance of Nitrospira. Moreover, PNCT did not lead to the sharp increase of absolute abundances of antibiotic resistance genes (ARGs), and the risk of ARGs transmission was negligible.202438744392
8610160.9860A 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
8616170.9860Mechanisms 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
8486180.9860Multidrug-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
7871190.9860Effects of different quaternary ammonium compounds on intracellular and extracellular resistance genes in nitrification systems under the pre-contamination of benzalkyl dimethylammonium compounds. As the harm of benzalkyl dimethylammonium compounds (BACs) on human health and environment was discovered, alkyltrimethyl ammonium compound (ATMAC) and dialkyldimethyl ammonium compound (DADMAC), which belong to quaternary ammonium compounds (QACs), were likely to replace BACs as the main disinfectants. This study simulated the iterative use of QACs to explore their impact on resistance genes (RGs) in nitrification systems pre-contaminated by BACs. ATMAC could initiate and maintain partial nitrification. DADMAC generated higher levels of reactive oxygen species and lactate dehydrogenase, leading to increased biological toxicity in bacteria. The abundance of intracellular RGs of sludge was higher with the stress of QACs. DADMAC also induced higher extracellular polymeric substance secretion. Moreover, it facilitated the transfer of RGs from sludge to water, with ATMAC disseminating RGs through si-tnpA-04 and DADMAC through si-intI1. Sediminibacterium might be potential hosts for RGs. This study offered insights into disinfectant usage in the post-COVID-19 era.202539612960