Response of microbial nitrogen transformation processes to antibiotic stress in a drinking water reservoir. - Related Documents




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853401.0000Response of microbial nitrogen transformation processes to antibiotic stress in a drinking water reservoir. Effects of antibiotics on microbial nitrogen transformation processes in natural aquatic ecosystems are largely unknown. In this study, we utilized the (15)N stable isotope tracers and metagenomic sequencing to identify how antibiotics drive nitrogen transformation processes in Danjiangkou Reservoir, which is the largest artificial drinking water reservoir in China. We retrieved 51 nitrogen functional genes, and found that the highest abundances of nitrate reduction and denitrification-related genes occurred in dissimilatory nitrogen transformation pathways. (15)N-labelling analysis substantiated that denitrification was the main pathway for nitrogen removal, accounting for 57.1% of nitrogen loss. Nitrogen functional genes and antibiotic resistance genes co-occurred in Danjiangkou Reservoir, and they were mainly carried by the denitrifying bacteria such as Rhodoferax, Polaromonas, Limnohabitans, Pararheinheimera, Desulfobulbus, and Pseudopelobacter. Genome annotation revealed that antibiotic deactivation, Resistance-Nodulation-Division and facilitator superfamily efflux pumps were responsible for the multiple-resistance to antibiotics in these bacteria. Moreover, antibiotics showed non-significant effects on nitrogen transformation processes. It is speculated that denitrifying bacteria harboring ARGs played crucial roles in protecting nitrogen transformation from low-level antibiotics stress in the reservoir. Our results highlight that denitrifying bacteria are important hosts of ARGs, which provides a novel perspective for evaluating the effects of antibiotics on nitrogen cycle in natural aquatic ecosystems.202134303244
756110.9997Deciphering antibiotic resistome variations during nitrogen removal process transition under mixed antibiotics stress: Assembly process and driving factors. Antibiotic resistome, which encompasses all types of antibiotic resistance genes (ARGs) in a given environment, has received increasing attention in research on different wastewater treatment processes. However, the variation in antibiotic resistome during the transition from the full nitrification-denitrification to the shortcut nitrification-denitrification process remains unclear. In this study, a total of 269 targeted gene subtypes were identified, along with 108 genes were consistently present in all samples. The introduction of mixed antibioticsrapidly increased the abundance of corresponding and non-corresponding ARGs, as well as that of mobile genetic elements.The variations in of the antibiotic resistome were primarily driven by dissolved oxygen and nitrite accumulation rate. Moreover, 34 bacterial genera were identified as potential ARG hosts, with most denitrifiers considered as potential antibiotic-resistant bacteria, including Branchymonas, Rhodobacter, and Thauera. This study provides a method for controlling antibiotic resistance by regulating the changes in environmental variables and bacterial communities.202339492537
856620.9997Synergistic Control of Trimethoprim and the Antimicrobial Resistome in Electrogenic Microbial Communities. Synergistic control of the risks posed by emerging antimicrobials and antibiotic resistance genes (ARGs) is crucial for ensuring ecological safety. Although electrogenic respiration can enhance the biodegradation of several antimicrobials and reduce ARGs accumulation, the association mechanisms of antimicrobial biodegradation (trimethoprim, TMP) with the fate of the antimicrobial resistome remain unclear. Here, the biotransformation pathway of TMP, microbial associations, and functional gene profiles (e.g., degradation, antimicrobial resistance, and electron transfer) were analyzed. The results showed that the microbial electrogenic respiration significantly enhanced the biodegradation of TMP, especially with a cosubstrate sodium acetate supply. Electroactive bacteria enriched in the electrode biofilm positively correlated with potential TMP degraders dominated in the planktonic communities. These cross-niche microbial associations may contribute to the accelerated catabolism of TMP and extracellular electron transfer. Importantly, the evolution and dissemination of overall ARGs and mobile genetic elements (MGEs) were significantly weakened due to the enhanced cometabolic biodegradation of TMP. This study provides a promising strategy for the synergistic control of the water ecological risks of antimicrobials and their resistome, while also highlighting new insights into the association of antimicrobial biodegradation with the evolution of the resistome in an electrically integrated biological process.202438299532
752430.9997Insights into the interactions of plant-associated bacteria and their role in the transfer of antibiotic resistance genes from soil to plant. This study discussed the role of plant-associated microbiome in regulating ARG transfer in soil-plant systems. Results showed that target ARGs in plants were mainly derived from rhizosphere soil. Cooperative interactions among bacteria in rhizosphere soil, plant-roots, plant-shoots, and soil-roots-shoots systems occurred during ARG transfer. The number of modules and keystone taxa identified as positively correlated with ARG transfer in rhizosphere soil, roots, and shoots was 3 and 49, 3 and 41, 2 and 5, respectively. Among these modules, module 3 in roots was significantly positively correlated with module 3 in rhizosphere soils and module 2 in shoots, indicating that module 3 in roots played central hub roles in ARG transfer from rhizosphere soil to roost and shoots. This may be because module 3 in roots increased cell motility and xenobiotics biodegradation and metabolism. These keystone taxa mainly belonged to Proteobacteria that can carry ARGs to transfer in soil-plant systems, especially Clostridium-sensu_stricito and Pseudomonas in rhizosphere soil carried ARGs into the shoot. Additionally, they promoted ARG transfer by increasing plant biomass, net photosynthetic rate and water use efficiency. The findings helped reveal the mechanism of plant-associated bacterial interactions and provided understanding for potential risks of ARG transfer from soil to plants.202439305593
856540.9997Deciphering the transfers of antibiotic resistance genes under antibiotic exposure conditions: Driven by functional modules and bacterial community. Antibiotics can exert selective pressures on sludge as well as affect the emergence and spread of antibiotic resistance genes (ARGs). However, the underlying mechanisms of ARGs transfers are still controversial and not fully understood in sludge system. In present study, two anaerobic sequence batch reactors (ASBR) were constructed to investigate the development of ARGs exposed to two sulfonamide antibiotics (SMs, sulfadiazine SDZ and sulfamethoxazole SMX) with increasing concentrations. The abundance of corresponding ARGs and total ARGs obviously increased with presence of SMs. Functional analyses indicated that oxidative stress response, signal transduction and type IV secretion systems were triggered by SMs, which would promote ARGs transfers. Network analysis revealed 18 genera were possible hosts of ARGs, and their abundances increased with SMs. Partial least-squares path modeling suggested functional modules directly influenced mobile genetic elements (MGEs) as well as the ARGs might be driven by both functional modules and bacteria community, while bacteria community composition played a more key role. Sludge with refractory antibiotics (SDZ) may stimulate the relevant functions and shift the microbial composition to a greater extent, causing more ARGs to emerge and spread. The mechanisms of ARGs transfers are revealed from the perspective of functional modules and bacterial community in sludge system for the first time, and it could provide beneficial directions, such as oxidative stress reduction, cellular communication control, bacterial composition directional regulation, for ARGs spread controlling in the future.202134563930
673650.9997Biotic pathways of reciprocal responses between antibiotic resistance genes and inorganic nitrogen cycling genes in amoxicillin-stressed compost ecosystems. This study explored the transformation of inorganic nitrogen, the expression levels of antibiotic resistance genes (ARGs), and the regulatory mechanisms of key species on ARGs and inorganic nitrogen cycling genes (INCGs) under different levels of amoxicillin (AMX) stress. High level of AMX inhibited the accumulation of NH(4)(+)-N, which increased by 531 % relative to the initial. Moreover, AMX to some extent increased the levels of nirS and nirK, which could potentially result in nitrogen loss and the accumulation of NO(2)(-). Actinobacteria might serve as potential hosts for ARGs during sludge composting. This stress induced a complex response between INCGs and ARGs more complex due to key species. Under high-level AMX pressure, most species associated with ARGs likely derived from nitrogen cycling functional species. To conclude, high levels of AMX stress might lead to nitrogen cycling imbalance and the dissemination of antibiotic resistance genes in composting systems.202438387840
751860.9997Deciphering the toxic effects of metals in gold mining area: Microbial community tolerance mechanism and change of antibiotic resistance genes. Mine tailing dumps represent significant threats to ecological environments due to the presence of toxic substances. The present work investigated the relationship among microbial activity, the community, antibiotic resistance genes (ARGs) and trace metals in soil surrounding gold mine tailings. Using microbial metabolic activity and high-throughput sequencing analysis, we found the trace metals Cd and Hg could be main factors influencing the microbial community. According to bacterial co-occurrence pattern analysis, the effects of total cadmium and total mercury on bacterial diversity are potentially mediated by influencing bacteria community in the keystone module II. Additionally, most of metal-resistant bacteria belong to Actinobacteria and Proteobacteria, and the metal tolerance suggested to be linked with various functions including replication, recombination and repair, as well as inorganic ion transport and metabolism based on PICRUSt2 analysis. We also found that metals generated by mining activity may trigger the co-selection of antibiotic resistance in the phyla Actinobacteria and Proteobacteria due to co-resistance or cross resistance. Additionally, PLS-PM analysis revealed that metals could indirectly affect ARGs by influencing bacterial diversity in gold mining areas.202032678731
751170.9997Antibiotic resistome promotion in drinking water during biological activated carbon treatment: Is it influenced by quorum sensing? The contamination of antibiotic resistance genes (ARGs) in drinking water may pose a direct threat to human health. This study applied high-throughput qPCR and sequencing to investigate the dynamics of ARGs and bacterial communities during the advanced treatment of drinking water using biological activated carbon. The promotion of ARGs was observed, and the normalized copy number of ARGs increased significantly after BAC treatment, raising the number of detected ARGs from 84 to 159. Twenty-nine ARGs were identified as biofilm-influencing sources in the BAC, and they persisted after chlorination. The shift of bacterial communities primarily had effects on the changes in resistome. Firmicutes, Cyanobacteria were related to persistent ARGs mostly in the BAC biofilm. Meanwhile, the Acyl-Homoserine Lactones (AHLs), quorum sensing molecules, and bacteria that produced AHLs were identified to understand the promotion of ARGs. The isolated AHL-producing bacteria belonged to the Proteobacteria, Firmicutes and Bacteroidetes phyla. Six detectable AHLs had an influence on plasmid-based horizontal gene transfer in the intragenus mating systems, indicating that the dynamics of ARGs were strongly affected by quorum sensing between specific bacteria in the biofilm. These results provide new insight into the mechanism of antibiotic resistome promotion in BAC biofilms.201828846900
851680.9997Graphene Oxide Inhibits Antibiotic Uptake and Antibiotic Resistance Gene Propagation. Antibiotics and antibiotic resistance genes (ARGs) in the natural environment have become substantial threats to the ecosystem and public health. Effective strategies to control antibiotics and ARG contaminations are emergent. A novel carbon nanomaterial, graphene oxide (GO), has attracted a substantial amount of attention in environmental fields. This study discovered the inhibition effects of GO on sulfamethoxazole (SMZ) uptake for bacteria and ARG transfer among microorganisms. GO promoted the penetration of SMZ from intracellular to extracellular environments by increasing the cell membrane permeability. In addition, the formation of a GO-SMZ complex reduced the uptake of SMZ in bacteria. Moreover, GO decreased the abundance of the sulI and intI genes by approximately 2-3 orders of magnitude, but the global bacterial activity was not obviously inhibited. A class I integron transfer experiment showed that the transfer frequency was up to 55-fold higher in the control than that of the GO-treated groups. Genetic methylation levels were not significant while sulI gene replication was inhibited. The biological properties of ARGs were altered due to the GO-ARG noncovalent combination, which was confirmed using multiple spectral analyses. This work suggests that GO can potentially be applied for controlling ARG contamination via inhibiting antibiotic uptake and ARG propagation.201627934199
795790.9997Differential size-dependent response patterns and antibiotic resistance development mechanism in anammox consortia. Antibiotic resistance is a global threat to human and animal health. Anaerobic ammonia oxidation (anammox) is an efficient and innovative wastewater treatment technology, which can be served as a promising approach to teat antibiotic wastewater. This study systematically investigated effects of sulfamethazine on the performance, microbial community dynamics and the resistome in anammox systems inoculated with different-sized granular sludge. The activity and performance of small (< 0.5 mm) anammox granules were more susceptible to sulfamethazine stress than those of medium (0.5-1.0 mm) and large (1.0-2.0 mm) granules. Sulfamethazine addition greatly increased the diversity and abundance of mobile genetic elements (MGEs) and antibiotic resistance genes (ARGs). Based on the metagenomic analysis, the horizontal transfer of ARGs in the anammox system was upregulated through bacterial oxidative stress, pili synthesis and type IV secretion system. In addition, two strains of sulfamethazine-resistant bacteria (Pseudomonas asiatica sp. nov. and Pseudomonas shirazica sp. nov.) were isolated from the anammox system. Their whole genome sequencing results showed that the most abundant plasmid was pkF7158B, which mediated the horizontal transfer of two main multidrug resistance genes (cpxR and mexB). This work provides a holistic insight into microbial heterogeneity of different-sized anammox granular sludge and their evolution and resistance development mechanism.202540086246
8574100.9997Impact of different manure-derived dissolved organic matters on the fate of arsenic-antibiotic in co-contaminated paddy soils. Manure application increases the transfer risk of antibiotic resistance to farmland. Especially, its impact remains unclear when it occurs in arsenic (As)-contaminated paddy soils, which is considered as a global environmental problem. In this work, we investigated the fate of antibiotic resistance genes (ARGs) in As-antibiotic co-contaminated paddy soils under the application of manure from different sources (pig manure, cow dung, and chicken manure). Differences in the aliphatic carbon and electron-donating capacities of these dissolved organic matters (DOM) regulated the transformation of iron and As by both biotic and abiotic processes. The regulation by pig manure was stronger than that by cow dung and chicken manure. DOM regulation increased the abundance of As-related functional genes (arsC, arrA, aioA, and arsM) in the soil and accelerated the transformation of As speciation, the highest proportion of As(III) being 45%-61%. Meanwhile, the continuous selection pressure provided by the highly toxic As(III) increased the risk of ARGs and mobile genetic elements (MGEs) via horizontal gene transfer. As-resistant bacteria, including Bacillus, Geobacter, and Desulfitobacterium, were finally considered as potential host bacteria for ARGs and MGEs. In summary, this study clarified the synergistic mechanism of As-antibiotic on the fate of ARGs in co-contaminated paddy soils, and provided practical guidance for the proper application of organic fertilizers.202235491001
8517110.9997Influences of graphene on microbial community and antibiotic resistance genes in mouse gut as determined by high-throughput sequencing. Graphene is a promising candidate as an antibacterial material owning to its bacterial toxicity. However, little information on influence of graphene on gut microbiota is available. In this study, mice were exposed to graphene for 4 weeks, and high-throughput sequencing was applied to characterize the changes in microbial community and antibiotic resistance genes (ARGs) in mouse gut. The results showed that graphene exposure increased biodiversity of gut microbiota, and changed their community. The 1 μg/d graphene exposure had higher influences on the gut microbiota than 10 μg/d and 100 μg/d graphene exposures, which might be due to higher aggregation of high-level graphene. The influence of graphene on gut microbiota might attribute to that graphene could induce oxidative stress and damage of cell membrane integrity. The results were verified by the increase of ratio of Gram-negative bacteria. Outer membrane of Gram-negative bacteria could reduce the membrane damage induced by graphene and make them more tolerance to graphene. Further, we found that graphene exposure significantly increased the abundance and types of ARGs, indicating a potential health risk of graphene. This study firstly provides new insight to the health effects of graphene on gut microbiota.201626476051
7031120.9996Free-living lifestyle preferences drive the antibiotic resistance promotion during drinking water chlorination. The risk associated with antibiotic resistance genes (ARGs) in size-fractionated bacterial community during drinking water chlorination remains unclear, and is of paramount importance for risk mitigation through process selection and optimization. This study employed metagenomic approaches to reveal the alterations of ARGs, their potential functions and hosts within the free-living and particle-associated fractions. The total relative abundance of ARGs, mobile genetic elements (MGEs), and virulence factor genes (VFGs) significantly increased in the free-living fraction after chlorination. The contribution of the free-living fraction to the ARG relative abundance rose from 16.40 ± 1.31 % to 93.62 ± 0.47 % after chlorination. Multidrug resistance genes (e.g. mexF and mexW) were major contributors, and their co-occurrence with MGEs in the free-living fraction was enhanced after chlorination. Considering multiple perspectives, including presence, mobility, and pathogenicity, chlorination led to a significant risk of the antibiotic resistome in the free-living fraction. Moreover, potential functions of ARGs, such as cell wall/membrane/envelope biogenesis, defense mechanisms, and transcription in the free-living fraction, were intensified following chlorination. Potential pathogens, including Pseudomonas aeruginosa, Pseudomonas alcaligenes, and Acinetobacter junii, were identified as the predominant hosts of multidrug resistance genes, with their increased abundances primarily contributing to the rise of the corresponding ARGs. Overall, alterations of hosts as well as enhancing mobility and biological functions could collectively aid the proliferation and spread of ARGs in the free-living fraction after chlorination. This study provides novel insights into antibiotic resistance evolution in size-fractionated bacteria community and offers a management strategy for microbiological safety in drinking water.202438043346
7523130.9996Transfer of antibiotic resistance genes from soil to wheat: Role of host bacteria, impact on seed-derived bacteria, and affecting factors. The transfer of antibiotic resistance genes (ARGs) from soils to plants is poorly understood, especially the role of host bacteria in soils and its impact on seed-derived bacteria. Wheat (Triticum aestivum L.) was thus used to fill the gap by conducting pot experiments, with target ARGs and bacterial community analyzed. Results showed that the relative abundances of target ARGs gradually decreased during transfer of ARGs from the rhizosphere soil to root and shoot. Host bacteria in the rhizosphere soil were the primary source of ARGs in wheat. The 38, 21, and 19 potential host bacterial genera of target ARGs and intI1 in the rhizosphere soil, root, and shoot were identified, respectively, and they mainly belonged to phylum Proteobacteria. The abundance of ARGs carried by pathogenic Corynebacterium was reduced in sequence. During transfer of ARGs from the rhizosphere soil to root and shoot, some seed-derived bacteria and pathogenic Acinetobacter obtained ARGs through horizontal gene transfer and became potential host bacteria. Furthermore, total organic carbon, available nitrogen of the rhizosphere soil, water use efficiency, vapor pressure deficit, and superoxide dismutase of plants were identified as the key factors affecting potential host bacteria transfer in soils to wheat. This work provides important insights into transfer of ARGs and deepens our understanding of potential health risks of ARGs from soils to plants.202337741386
8649140.9996Antibiotic-Induced Recruitment of Specific Algae-Associated Microbiome Enhances the Adaptability of Chlorella vulgaris to Antibiotic Stress and Incidence of Antibiotic Resistance. Insights into the symbiotic relation between eukaryotic hosts and their microbiome lift the curtain on the crucial roles of microbes in host fitness, behavior, and ecology. However, it remains unclear whether and how abiotic stress shapes the microbiome and further affects host adaptability. This study first investigated the effect of antibiotic exposure on behavior across varying algae taxa at the community level. Chlorophyta, in particular Chlorella vulgaris, exhibited remarkable adaptability to antibiotic stress, leading to their dominance in phytoplankton communities. Accordingly, we isolated C. vulgaris strains and compared the growth of axenic and nonaxenic ones under antibiotic conditions. The positive roles of antibiotics in algal growth were apparent only in the presence of bacteria. Results of 16S rRNA sequencing further revealed that antibiotic challenges resulted in the recruitment of specific bacterial consortia in the phycosphere, whose functions were tightly linked to the host growth promotion and adaptability enhancement. In addition, the algal phycosphere was characterized with 47-fold higher enrichment capability of antibiotic resistance genes (ARGs) than the surrounding water. Under antibiotic stress, specific ARG profiles were recruited in C. vulgaris phycosphere, presumably driven by the specific assembly of bacterial consortia and mobile genetic elements induced by antibiotics. Moreover, the antibiotics even enhanced the dissemination potential of the bacteria carrying ARGs from the algal phycosphere to broader environmental niches. Overall, this study provides an in-depth understanding into the potential functional significance of antibiotic-mediated recruitment of specific algae-associated bacteria for algae adaptability and ARG proliferation in antibiotic-polluted waters.202337642958
8563150.9996Overlooked role of extracellular polymeric substances in antibiotic-resistance gene transfer within microalgae-bacteria system. Controlling the spread of antibiotic-resistance genes (ARGs) under antibiotic stress has become an increasingly urgent issue. Microalgae possess the capability to remove antibiotics while concurrently inhibiting ARGs. Microalgae-bacteria systems can produce significant quantities of extracellular polymeric substances (EPS). However, the roles of EPS in the spread of ARGs have not been sufficiently explored, resulting in an insufficient understanding of the contribution of each EPS component and a lack of analysis on the complex interactions between EPS and ARGs. This study systematically explored the overlooked role of EPS in the transmission of ARGs within microalgae-bacteria systems. The current results showed that the potential of the microalgae-bacteria system for treating antibiotic wastewater. The tightly bound-EPS (TB-EPS) can acquire the higher absolute abundances of ARGs compared with the loosely bound-EPS (LB-EPS). The correlation coefficient between polysaccharides and TB-EPS ARGs was higher than that between polysaccharides and LB-EPS ARGs. The gene patterns of LB-EPS closely clustered with those of TB-EPS, while intracellular ARG gene patterns differed from both TB-EPS and LB-EPS. Metagenomic analyses indicated that the relative abundances of sul1 and sul2 were considerably higher at the beginning stage compared to the end stage. The abundance of Achromobacter, increased by the end stage, aligning with its potential to produce exopolysaccharide. Additionally, the absolute abundance of genes encoding exopolysaccharides (nagB and galE) and conjugative transfer transcription regulator (traF), increased over time. These findings enhanced our comprehension of the significance of EPS on the fate of ARGs in microalgae-bacteria systems during the treatment of antibiotic-contaminated wastewater.202539879767
9636160.9996A comprehensive review on biodegradation of tetracyclines: Current research progress and prospect. The release of tetracyclines (TCs) in the environment is of significant concern because the residual antibiotics may promote resistance in pathogenic microorganisms, and the transfer of antibiotic resistance genes poses a potential threat to ecosystems. Microbial biodegradation plays an important role in removing TCs in both natural and artificial systems. After long-term acclimation, microorganisms that can tolerate and degrade TCs are retained to achieve efficient removal of TCs under the optimum conditions (e.g. optimal operational parameters and moderate concentrations of TCs). To date, cultivation-based techniques have been used to isolate bacteria or fungi with potential degradation ability. Moreover, the biodegradation mechanism of TCs can be unveiled with the development of chemical analysis (e.g. UPLC-Q-TOF mass spectrometer) and molecular biology techniques (e.g. 16S rRNA gene sequencing, multi-omics sequencing, and whole genome sequencing). In this review, we made an overview of the biodegradation of TCs in different systems, refined functional microbial communities and pure isolates relevant to TCs biodegradation, and summarized the biodegradation products, pathways, and degradation genes of TCs. In addition, ecological risks of TCs biodegradation were considered from the perspectives of metabolic products toxicity and resistance genes. Overall, this article aimed to outline the research progress of TCs biodegradation and propose future research prospects.202234995606
7496170.9996Effects of microplastics and tetracycline induced intestinal damage, intestinal microbiota dysbiosis, and antibiotic resistome: metagenomic analysis in young mice. Microplastics (MPs) and antibiotic tetracycline (TC) are widespread in the environment and constitute emerging combined contaminants. Young individuals are particularly vulnerable to agents that disrupt intestinal health and development. However, the combined effects of MPs and TC remain poorly understood. In this study, we developed a young mouse model exposed to polystyrene MPs, either alone or in combination with TC for 8 weeks to simulate real-life dietary exposure during early life. Our findings revealed that concurrent exposure to MPs and TC caused the most severe intestinal barrier dysfunction driven by inflammatory activation and oxidative imbalance. Moreover, exposure to MPs and TC reduced the abundance of potential probiotics while promoting the growth of opportunistic pathogens. Metagenomic analysis further indicated that co-exposure to MPs and TC enhanced the abundance of bacteria carrying either antibiotic resistance genes (ARGs) or virulence factor genes (VFGs), contributing to the widespread dissemination of potentially harmful genes. Finally, a strong positive correlation was observed between microbiota dysbiosis, ARGs, and VFGs. In general, this study highlighted the hazards of MPs and antibiotics to intestinal health in young mice, which provided a new perspective into the dynamics of pathogens, ARGs, and VFGs in early-life intestinal environments.202540328090
6985180.9996Elevated CO(2) Increased Antibiotic Resistomes in Seed Endophytes: Evidence from a Free-Air CO(2) Enrichment (FACE) Experiment. Climate warming affects antibiotic resistance genes (ARGs) in soil and the plant microbiome, including seed endophytes. Seeds act as vectors for ARG dissemination in the soil-plant system, but the impact of elevated CO(2) on seed resistomes remains poorly understood. Here, a free-air CO(2) enrichment system was used to examine the impact of elevated CO(2) on seed-associated ARGs and seed endophytic bacteria and fungi. Results indicated that elevated CO(2) levels significantly increased the relative abundance of seed ARGs and mobile genetic elements (MGEs), especially those related to beta-lactam resistance and MGEs. Increased CO(2) levels also influenced the composition of seed bacterial and fungal communities and the complexity of bacteria-fungi interactions. Fungi were more sensitive to changes in the CO(2) level than bacteria, with deterministic processes playing a greater role in fungal community assembly. Co-occurrence network analysis revealed a stronger correlation between fungi and ARGs compared to bacteria. The structure equation model (SEM) showed that elevated CO(2) directly influenced seed resistomes by altering bacterial composition and indirectly through bacteria-fungi interactions. Together, our work offers new insights into the effects of elevated CO(2) on antibiotic resistomes in the seed endosphere, highlighting their increased dissemination potential within soil-plant systems and the associated health risks in a changing environment.202439680930
7565190.9996Microalgae Enhances the Adaptability of Epiphytic Bacteria to Sulfamethoxazole Stress and Proliferation of Antibiotic Resistance Genes Mediated by Integron. The transmission of ARGs in the microalgae-associated epiphytic bacteria remains unclear under antibiotic exposure, apart from altering the microbial community structure. In this study, Chlorella vulgaris cocultured with bacteria screened from surface water was examined to explore the spread of ARGs in the presence of sulfamethoxazole (SMX). The extracellular polymers released by Chlorella vulgaris could reduce antibiotic-induced collateral damage to bacteria, thus increasing the diversity of the microalgae-associated epiphytic bacteria. The abundances of sul1 and intI1 in the phycosphere at 1 mg/L SMX dose increased by 290 and 28 times, respectively. Metagenomic sequencing further confirmed that SMX bioaccumulation stimulated the horizontal transfer of sul1 mediated by intI1 in the microalgae-associated epiphytic bacteria, while reactive oxygen species (ROS)-mediated oxidative stress induced the SOS response and thus enhanced the transformation of sul1 in the J group. This is the first study to verify that microalgae protect bacteria from antibiotic damage and hinder the spread of ARGs mediated by SOS response, while the transfer of ARGs mediated by integron is promoted due to the bioaccumulation of SMX in the phycosphere. The results contribute to present comprehensive understanding of the risk of ARG proliferation by the presence of emerging contaminants residues in river.202439417646