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693700.9916Differential responses of bacterial and archaeal communities to biodegradable and non-biodegradable microplastics in river. Microplastics are widespread environmental pollutants that pose risks to ecosystems, yet their effects on bacterial and archaeal communities in aquatic ecosystems remain understudied. In this study, we performed a 14-day microcosm experiment combined with metagenomic sequencing to compare bacterial and archaeal responses to a biodegradable microplastic (polylactic acid, PLA) and a non-biodegradable microplastic (polyvinyl chloride, PVC). Microplastics selectively enriched distinct microbial assemblages, with Pseudomonadota and Euryarchaeota identified as the dominant bacterial and archaeal phyla, accounting for 67.83 % and 15.95 %, respectively. Archaeal community in surrounding water were more sensitive to colonization time than bacterial community. Compared to the surrounding water, the plastisphere displayed simpler and more loosely connected microbial networks. Notably, co-occurrence networks of both bacteria and archaea in the PVC plastisphere were predominantly shaped by symbiotic interactions. Both bacteria and archaea carried diverse antibiotic resistance genes (ARGs), but PLS-PM indicated that bacteria were the primary drivers of ARG dissemination (path coefficient = 0.952). While the PVC plastisphere showed higher ARG abundance than the PLA plastisphere, elevated intI1 expression in the PLA plastisphere suggests a potentially greater risk of ARG dissemination associated with PLA microplastics. These findings reveal the distinct effects of PLA and PVC microplastics on microbial communities and highlight the role of microplastics in ARG dissemination, emphasizing their ecological risks in aquatic ecosystems.202540712359
692110.9915Impacts of Chemical and Organic Fertilizers on the Bacterial Communities, Sulfonamides and Sulfonamide Resistance Genes in Paddy Soil Under Rice-Wheat Rotation. The responses of sulfonamides, sulfonamide-resistance genes (sul) and soil bacterial communities to different fertilization regimes were investigated by performing a field experiment using paddy soil with no fertilizer applied, chemical fertilizer applied, organic fertilizer applied, and combination of chemical and organic fertilizer applied. Applying organic fertilizer increased the bacterial community diversity and affected the bacterial community composition. Eutrophic bacteria (Bacteroidetes, Gemmatimonadetes, and Proteobacteria) were significantly enriched by applying organic fertilizer. It was also found organic fertilizer application increased sulfamethazine content and the relative abundances of sul1 and sul2 in the soil. In contrast, applying chemical fertilizer significantly increased the abundance of Nitrospirae, Parcubacteria, and Verrucomicrobia and caused no obvious changes on sul. Correlation analysis indicated that sul enrichment was associated with the increases in sulfamethazine content and potential hosts (e.g., Novosphingobium and Rhodoplanes) population. The potential ecological risks of antibiotics in paddy soil with organic fertilizer applied cannot be ignored.202236547725
693420.9915Impact of protist predation on bacterial community traits in river sediments. Sediment-associated microbial communities are pivotal in driving biogeochemical processes and serve as key indicators of ecosystem health and function. However, the ecological impact of protist predation on these microbial communities remains poorly understood. Here, sediment microcosms were established with varying concentrations of indigenous protists. Results revealed that protist predation exerted strong and differential effects on the bacterial community composition, functional capabilities, and antibiotic resistance profiles. Higher levels of protist predation pressure increased bacterial alpha diversity and relative abundance of genera associated with carbon and nitrogen cycling, such as Fusibacter, Methyloversatilis, Azospirillum, and Holophaga. KEGG analysis indicated that protist predation stimulated microbial processes related to the carbon, nitrogen, and sulfur cycles. Notably, the relative abundance and associated health risks of antibiotic resistance genes (ARGs), virulence factor genes (VFGs), and mobile genetic elements (MGEs) were affected by predation pressure. Medium protist predation pressure increased the relative abundance and potential risks associated with ARGs, whereas high protist concentrations led to a reduction in both, likely due to a decrease in the relative abundance of ARG-hosting pathogenic bacteria such as Pseudomonas, Acinetobacter, and Aeromonas. These findings provide comprehensive insights into the dynamics of bacterial communities under protist predation in river sediment ecosystems.202540885182
811130.9914Effect 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
792940.9913Size-dependent effects of microplastics on antibiotic resistance genes fate in wastewater treatment systems: The role of changed surface property and microbial assemblages in a continuous exposure mode. Microplastics (MPs) were continuously transported to wastewater treatment systems and accumulated in sludge constantly, potentially affecting systems function and co-occurrent contaminants fate. However, previous studies were based on acute exposure of MPs, which could not reflect the dynamics of MPs accumulation. Herein, this study firstly raised a more realistic method to evaluate the practical impacts of MPs on systems purification efficiency and antibiotic resistance genes (ARGs) fate. Continuous exposure of MPs did not pose negative effects on nutrients removal, but significantly changed the occurrence patterns of ARGs. ARGs abundances increased by 42.8 % and 54.3 % when exposed to millimeter-size MPs (mm-MPs) polyamide and polyethylene terephthalate, but increased by 31.3 % and 39.4 % to micron-size MPs (μm-MPs), respectively. Thus, mm-MPs posed severer effects on ARGs than μm-MPs. Further, mm-MPs surface properties were obviously altered after long-term exposure (higher specific surface area and O-containing species), which benefited microbes attachment. More importantly, more taxa linkages and changed topological properties (higher average degree and average weight) of co-occurrent network were observed in sludge with mm-MPs than with μm-MPs, as well as totally different potential host bacteria of ARGs. Rough surface of MPs and closer relations between ARGs and bacteria taxa contributed to the propagation of ARGs, which accounted for the observed higher ARGs abundances of mm-MPs. This study demonstrated that long-term accumulation of MPs in wastewater treatment systems affected ARGs fate, and mm-MPs caused severer risk due to their enrichment of ARGs. The results would promote the understanding of MPs real environmental behavior and influences.202236037899
864450.9913Biotic and abiotic drivers of soil carbon, nitrogen and phosphorus and metal dynamic changes during spontaneous restoration of Pb-Zn mining wastelands. The biotic and abiotic mechanisms that drive important biogeochemical processes (carbon, nitrogen, phosphorus and metals dynamics) in metal mine revegetation remains elusive. Metagenomic sequencing was used to explored vegetation, soil properties, microbial communities, functional genes and their impacts on soil processes during vegetation restoration in a typical Pb-Zn mine. The results showed a clear niche differentiation between bacteria, fungi and archaea. Compared to bacteria and fungi, the archaea richness were more tightly coupled with natural restoration changes. The relative abundances of CAZyme-related, denitrification-related and metal resistance genes reduced, while nitrification, urease, inorganic phosphorus solubilisation, phosphorus transport, and phosphorus regulation -related genes increased. Redundancy analysis, hierarchical partitioning analysis, relative-importance analysis and partial least squares path modelling, indicated that archaea diversity, primarily influenced by available lead, directly impacts carbon dynamics. Functional genes, significantly affected by available cadmium, directly alter nitrogen dynamics. Additionally, pH affects phosphorus dynamics through changes in bacterial diversity, while metal dynamics are directly influenced by vegetation. These insights elucidate natural restoration mechanisms in mine and highlight the importance of archaea in soil processes.202540054196
812360.9913The effect of bulk-biochar and nano-biochar amendment on the removal of antibiotic resistance genes in microplastic contaminated soil. Biochar amendment has significant benefits in removing antibiotic resistance genes (ARGs) in the soil. Nevertheless, there is little information on ARGs removal in microplastic contaminated soil. Herein, a 42-day soil microcosm experiment were carried out to study how two coconut shell biochars (bulk- and nano-size) eliminate soil ARGs with/without microplastic presence. The results showed that microplastic increased significantly the numbers and abundances of ARGs in soil at 14d of cultivation. And, two biochars amendment effectively inhibited soil ARGs spread whether or not microplastic was present, especially for nano-biochar which had more effective removal compared to bulk-biochar. However, microplastic weakened soil ARGs removal after applying same biochar. Two biochars removed ARGs through decreasing horizontal gene transfer (HGT) of ARGs, potential host-bacteria abundances, some bacteria crowding the eco-niche of hosts and promoting soil properties. The adverse effect of microplastic on ARGs removal was mainly caused by weakening mobile genetic elements (MGEs) removal, and by changing soil properties. Structural equation modeling (SEM) analysis indicated that biochar's effect on ARGs profile was changed by its size and microplastic presence through altering MGEs abundances. These results highlight that biochar amendment is still an effective method for ARGs removal in microplastic contaminated soil.202437907163
693870.9912Assessment of the Effects of Biodegradable and Nonbiodegradable Microplastics Combined with Pesticides on the Soil Microbiota. Microplastics (MPs) and pesticides pose significant threats to the health of soil ecosystems. This study investigated the individual and combined effects of biodegradable polylactic acid (PLA) and nonbiodegradable polyethylene terephthalate (PET) microplastics alongside glyphosate and imidacloprid pesticides on soil microbial communities and antibiotic resistance genes (ARGs) via microcosm experiments. Compared with the control, PLA significantly increased microbial alpha diversity and enhanced microbial functions related to environmental information processing and metabolism. However, PLA also selectively enriched populations of beneficial and potentially pathogenic bacteria, whereas PET had comparatively weaker effects. Crucially, PLA exposure resulted in substantially higher total abundance and ecological risk levels of soil ARGs than did PET. Coexposure with pesticides further amplified these effects, with PLA demonstrating notable synergistic interactions with both glyphosate and imidacloprid. These findings challenge the conventional assumption that biodegradable MPs such as PLA are environmentally safer than nonbiodegradable MPs, thus highlighting their potential to induce more complex and potentially severe ecological risks under co-contamination scenarios with pesticides.202541175058
792880.9912Insight into the responses of antibiotic resistance genes in microplastic biofilms to zinc oxide nanoparticles and zinc ions pressures in landfill leachate. Microplastic (MP) biofilms are hotspots of antibiotic resistance genes (ARGs) in landfill environment. MP biofilms in landfill leachate coexist with heavy metals and metallic nanoparticles (NPs) that considered to be the selective agents of ARGs. However, the effects of these selective pressures on ARGs in MP biofilms and their differences in MP-surrounding leachate have not been well understood. Herein, the changes of ARG abundances in MP biofilms and corresponding leachate under zinc oxide (ZnO) NPs and zinc ion (Zn(2+)) pressures were comparatively analyzed. The presence of ZnO NPs and Zn(2+) promoted the enrichment of ARGs in MP biofilms, and the enrichment was more pronounced in ZnO NPs groups. ZnO NPs and especially Zn(2+) mainly decreased the abundances of ARGs in leachate. The increase of integron abundances and reactive oxygen species production in MP biofilms implied the enhanced potential for horizontal transfer of ARGs under ZnO NPs and Zn(2+) pressures. Meanwhile, the co-occurrence pattern between ARGs and bacterial genera in MP biofilms with more diverse potential ARG hosts was more complex than in leachate, and the enrichment of ARG-hosting bacteria in MP biofilms under ZnO NPs and Zn(2+) pressures supported the enrichment of ARGs.202337480611
794090.9911Microplastics affect the ammonia oxidation performance of aerobic granular sludge and enrich the intracellular and extracellular antibiotic resistance genes. Microplastics (MPs) and antibiotic resistance genes (ARGs), as emerging pollutants, are frequently detected in wastewater treatment plants, and their threats to the environment have received extensive attentions. However, the effects of MPs on the nitrification of aerobic granular sludge (AGS) and the spread patterns of intracellular and extracellular ARGs (iARGs and eARGs) in AGS were still unknown. In this study, the responses of AGS to the exposure of 1, 10 and 100 mg/L of typical MPs (polyvinyl chloride (PVC), polyamide (PA), polystyrene (PS) and polyethylene (PE)) and tetracycline were focused on in 3 L nitrifying sequencing batch reactors. 10 mg/L MPs decreased the nitrification function, but nitrification could recover. Furthermore, MPs inhibited ammonia-oxidizing bacteria and enriched nitrite-oxidizing bacteria, leading partial nitrification to losing stability. PVC, PA and PS stimulated the secretion of extracellular polymeric substances and reactive oxygen species. PE had less negative effect on AGS than PVC, PA and PS. The abundances of iARGs and eARGs (tetW, tetE and intI1) increased significantly and the intracellular and extracellular microbial communities obviously shifted in AGS system under MPs stress. Potential pathogenic bacteria might be the common hosts of iARGs and eARGs in AGS system and were enriched in AGS and MPs biofilms.202133387747
6926100.9911Insights into the driving factors of vertical distribution of antibiotic resistance genes in long-term fertilized soils. The prevalence of antibiotic resistance genes (ARGs) in soils has aroused wide attention. However, the influence of long-term fertilization on the distribution of ARGs in different soil layers and its dominant drivers remain largely unknown. In this study, a total of 203 ARGs were analyzed in greenhouse vegetable soils (0-100 cm from a 13-year field experiment applied with different fertilizers (control, chemical fertilizer, organic manure, and mixed fertilizer). Compared with unfertilized and chemically fertilized soils, manure application significantly increased the abundance and alpha diversity of soil ARGs, where the assembly of ARG communities was strongly driven by stochastic processes. The distribution of ARGs was significantly driven by manure application within 60 cm, while it was insignificantly changed in soil below 60 cm under different fertilization regimes. The inter-correlations of ARGs with mobile genetic elements (MGEs) and microbiota were strengthened in manured soil, indicating manure application posed a higher risk for ARGs diffusion in subsurface soil. Bacteria abundance and MGEs directly influenced ARG abundance and composition, whereas soil depth and manure application indirectly influenced ARG abundance and composition by affecting antibiotics. These results strengthen our understanding of the long-term anthropogenic influence on the vertical distribution of soil ARGs and highlight the ecological risk of ARGs in subsurface soil induced by long-term manure application.202337247491
6991110.9910Distribution and drivers of antibiotic resistance genes in brackish water aquaculture sediment. Brackish water aquaculture has brought numerous economic benefits, whereas anthropogenic activities in aquaculture may cause the dissemination of antibiotic resistance genes (ARGs) in brackish water sediments. The intricate relationships between environmental factors and microbial communities as well as their role in ARGs dissemination in brackish water aquaculture remain unclear. This study applied PCR and 16S sequencing to identify the variations in ARGs, class 1 integron gene (intI1) and microbial communities in brackish water aquaculture sediment. The distribution of ARGs in brackish water aquaculture sediment was similar to that in freshwater aquaculture, and the sulfonamide resistance gene sul1 was the indicator of ARGs. Proteobacteria and Firmicutes were the dominant phyla, and Paenisporosarcina (p_ Firmicutes) was the dominant genus. The results of correlation, network and redundancy analysis indicated that the microbial community in the brackish water aquaculture sediment was function-driven. The neutral model and variation partitioning analysis were used to verify the ecological processes of the bacterial community. The normalized stochasticity ratio showed that pond bacteria community was dominated by determinacy, which was affected by aquaculture activities. The total nitrogen and organic matter influenced the abundance of ARGs, while Proteobacteria and Thiobacillus (p_Proteobacteria) were the key antibiotic-resistant hosts. Our study provides insight into the prevalence of ARGs in brackish water aquaculture sediments, and indicates that brackish water aquaculture is a reservoir of ARGs.202336436623
7941120.9909Microplastics accelerate nitrification, shape the microbial community, and alter antibiotic resistance during the nitrifying process. Microplastics (MPs) and antibiotic resistance genes (ARGs) are both emerging pollutants that are frequently detected in wastewater treatment plants. In this study, the effects of various MPs, including polyethylene (PE), polyvinyl chloride (PVC), and biodegradable polylactic acid (PLA), on nitrification performance, dominant microbial communities, and antibiotic resistance during nitrification were investigated. The results revealed that the addition of MPs increased the specific ammonia oxidation rate and specific nitrate production rate by 15.2 % - 15.5 % and 8.0 % - 11.6 %, respectively, via enrichment of nitrifying microorganisms, Nitrospira and Nitrosomonas. Moreover, ARGs were selectively enriched in nitrifying sludge and microplastic biofilms under stress from different MPs. Compared with PE-MPs (23.9 %) and PVC-MPs (21.4 %), exposure to PLA-MPs significantly increased intI1 abundance by 51.6 %. The results of the variance decomposition analysis implied that MPs and the microbial community play important roles in the behavior of ARGs. Network analysis indicated that Nitrosomonas and potentially pathogenic bacteria emerged as possible hosts, harboring ARGs and intI1 genes in the nitrifying sludge and microplastic biofilms. Critically, PLA-MPs were found to enrich both ARGs and potential pathogenic bacteria during nitrification, which should be considered in their promotion of application processes due to their biodegradability.202539740624
7950130.9909Fate and removal of fluoroquinolone antibiotics in mesocosmic wetlands: Impact on wetland performance, resistance genes and microbial communities. The fate of fluoroquinolone antibiotics norfloxacin and ofloxacin were investigated in mesocosmic wetlands, along with their effects on nutrients removal, antibiotic resistance genes (ARGs) and epiphytic microbial communities on Hydrilla verticillate using bionic plants as control groups. Approximately 99% of norfloxacin and ofloxacin were removed from overlaying water, and H. verticillate inhibited fluoroquinolones accumulation in surface sediments compared to bionic plants. Partial least squares path modeling showed that antibiotics significantly inhibited the nutrient removal capacity (0.55) but had no direct effect on plant physiology. Ofloxacin impaired wetland performance more strongly than norfloxacin and more impacted the primary microbial phyla, whereas substrates played the most decisive role on microbial diversities. High antibiotics concentration shifted the most dominant phyla from Proteobacteria to Bacteroidetes and inhibited the Xenobiotics biodegradation function, contributing to the aggravation in wetland performance. Dechloromonas and Pseudomonas were regarded as the key microorganisms for antibiotics degradation. Co-occurrence network analysis excavated that microorganisms degrade antibiotics mainly through co-metabolism, and more complexity and facilitation/reciprocity between microbes attached to submerged plants compared to bionic plants. Furthermore, environmental factors influenced ARGs mainly by altering the community dynamics of differential bacteria. This study offers new insights into antibiotic removal and regulation of ARGs accumulation in wetlands with submerged macrophyte.202438569335
6920140.9909Dynamics and key drivers of antibiotic resistance genes during aerobic composting amended with plant-derived and animal manure-derived biochars. Plant-derived and animal manure-derived biochars have been used to improve the quality of compost but the differences in their effects on antibiotic resistance genes (ARGs) during composting are unclear. This study selected two types of biochar (RB and PB) produced from abundant agricultural waste to be added to the compost. Adding plant-derived RB performed better in ARGs, mobile genetic elements, and human pathogenic bacteria removal during aerobic composting, whereas adding manure-derived PB even increased ARGs abundance. Vertical gene transfer was possibly the key mechanism for persistent ARGs, and easily removed ARGs were regulated by horizontal and vertical gene transfer. Adding plant-derived RB reduced the abundances of persistent ARG hosts (e.g., Pseudomonas and Longispora) and ARG-related metabolic pathways and genes. The higher nitrogen content of manure-derived PB may have promoted the proliferation of ARG hosts. Overall, adding manure-derived biochar during composting may not be the optimal option for eliminating ARGs.202235487450
6918150.9909Variations in antibiotic resistance genes and removal mechanisms induced by C/N ratio of substrate during composting. For a comprehensive insight into the potential mechanism of the removal of antibiotic resistance genes (ARGs) removal induced by initial substrates during composting, we tracked the dynamics of physicochemical properties, bacterial community composition, fungal community composition, the relative abundance of ARGs and mobile genetic genes (MGEs) during reed straw and cow manure composting with different carbon to nitrogen ratio. The results showed that the successive bacterial communities were mainly characterized by the dynamic balance between Firmicutes and Actinobacteria, while the fungal communities were composed of Ascomycota. During composting, the interactions between bacteria and fungi were mainly negative. After composting, the removal efficiency of ARGs in compost treatment with C/N ≈ 26 (LL) was higher than that in compost treatment with C/N ≈ 35 (HL), while MGEs were completely degraded in HL and enriched by 2.3% in LL. The large reduction in the relative abundance of ARGs was possibly due to a decrease in the potential host bacterial genera, such as Advenella, Tepidimicrobium, Proteiniphilum, Acinetobacter, Pseudomonas, Flavobacteria and Arcbacter. Partial least-squares path modeling (PLS-PM) revealed that the succession of bacterial communities played a more important role than MGEs in ARGs removal, while indirect factors of the fungal communities altered the profile of ARGs by affecting the bacterial communities. Both direct and indirect factors were affected by composting treatments. This study provides insights into the role of fungal communities in affecting ARGs and highlights the role of different composting treatments with different carbon to nitrogen ration on the underlying mechanism of ARGs removal.202134375241
6935160.9909Effects of soil protists on the antibiotic resistome under long term fertilization. Soil protists are key in regulating soil microbial communities. However, our understanding on the role of soil protists in shaping antibiotic resistome is limited. Here, we considered the diversity and composition of bacteria, fungi and protists in arable soils collected from a long-term field experiment with multiple fertilization treatments. We explored the effects of soil protists on antibiotic resistome using high-throughput qPCR. Our results showed that long term fertilization had stronger effect on the composition of protists than those of bacteria and fungi. The detected number and relative abundance of antibiotic resistance genes (ARGs) were elevated in soils amended with organic fertilizer. Co-occurrence network analysis revealed that changes in protists may contribute to the changes in ARGs composition, and the application of different fertilizers altered the communities of protistan consumers, suggesting that effects of protistan communities on ARGs might be altered by the top-down impact on bacterial composition. This study demonstrates soil protists as promising agents in monitoring and regulating ecological risk of antibiotic resistome associated with organic fertilizers.202235609845
7943170.9909Effects of microplastics on dissipation of oxytetracycline and its relevant resistance genes in soil without and with Serratia marcescens: Comparison between biodegradable and conventional microplastics. The biodegradable (polybutylene adipate terephthalate: PBAT) and conventional (polyethylene: PE) microplastics (MPs) at 0.5 %, 1 %, and 2 % dosages (w/w) were added into soils with and without Serratia marcescens ZY01 (ZY01, a tet-host strain) to understand their different effects on the dissipation of oxytetracycline (OTC) and tet. The results showed that the dosages of PBAT MP exhibited different inhibition degrees of OTC biodegradation in soils regardless of ZY01, while the dosages of PE MP did not change the enhancement degree of OTC biodegradation in soils without ZY01. These differences were due to the higher adsorption capacity of OTC on PBAT MP and the stronger toxicity of PBAT MP to microorganisms. Besides soil organic matter, pH and total phosphorus were important factors regulating specific tet-host bacteria in soils with MPs (e.g., the nitrogen-cycling bacteria Steroidobacter and Nitrospira) and MPs + ZY01 (e.g., the phosphorus-cycling bacteria Saccharimonadales and Haliangium), respectively. Regardless of ZY01, a stronger selective harboring of tet-host bacteria in PE MP treatments than PBAT MP treatments was observed at the MP dosage of 1 % (w/w), while the opposite trend was true at the MP dosages of 0.5 % and 2 % (w/w). Some specific genera belonging to Actinobacteriota strongly associated with the class 1 integron-integrase gene (intI1), playing a critical role in the horizontal gene transfer of tet in soils especially for the co-existence of MPs and ZY01. This study will be helpful for understanding on how biodegradable and conventional MPs as hotspots affect the environmental behavior of antibiotics and ARGs in soil.202439500253
6913180.9909Antibiotic resistance genes link to nitrogen removal potential via co-hosting preference for denitrification genes in a subtropical estuary. Estuaries are important sinks for antibiotic resistance genes (ARGs) and hotspots of nitrogen cycling. However, the interactions between nitrogen cycling functional genes (NCGs) and ARGs in estuaries remain poorly understood. This study employed metagenomic sequencing to explore potential interactions between nitrogen, ARGs, and microbial-mediated nitrogen cycling processes in estuarine waters. Results showed beta-lactam was the predominant subtype of ARGs (407 species), and sul1 exhibited the highest relative abundance (4.11 %). Nitrogen was the important factor driving spatiotemporal variation of ARGs, promoting their proliferation and dispersal by enhancing microbial growth and reproduction. Network analysis revealed wide and complex correlations between ARGs and NCGs. Nitrate-reducing bacteria were the main hosts of ARGs, and the greatest number of potential hosts were those involved in assimilatory nitrate reduction to ammonium (17.44 %), dissimilatory nitrate reduction to nitrite (16.59 %), and denitrification (15.71 %). Compared with dissimilatory nitrite reduction to ammonium genes, ARGs prefer to form co-hosting relationships with denitrification genes, indicating that ARGs had a stronger effect on the nitrogen removal potential than on the nitrogen retention potential. This study highlights the complex interactions between ARGs and nitrogen cycling processes in subtropical estuaries, and will provide a scientific base for couple management strategies of nitrogen and antibiotic pollution.202540934587
6915190.9908Industrial-scale aerobic composting of livestock manures with the addition of biochar: Variation of bacterial community and antibiotic resistance genes caused by various composting stages. The presence of large amounts of antibiotic resistance genes (ARGs) in livestock manures poses an impending, tough safety risk to ecosystems. To investigate more comprehensively the mechanisms of ARGs removal from industrial-scale composting of livestock manure based on biochar addition, we tracked the dynamics of bacterial community and ARGs at various stages of aerobic composting of livestock manures with 10% biochar. There were no significant effects of biochar on the bacterial community and the profiles of ARGs. During aerobic composting, the relative abundance of ARGs and mobile genetic elements (MGEs) showed overall trends of decreasing and then increasing. The key factor driving the dynamics of ARGs was bacterial community composition, and the potential hosts of ARGs were Caldicoprobacter, Tepidimicrobium, Ignatzschineria, Pseudogracilibacillus, Actinomadura, Flavobacterium and Planifilum. The retention of the thermophilic bacteria and the repopulation of the initial bacteria were the dominant reasons for the increase in ARGs at maturation stage. Additionally, among the MGEs, the relative abundance of transposon gene was substantially removed, while the integron genes remained at high relative abundance. Our results highlighted that the suitability of biochar addition to industrial-scale aerobic composting needs to be further explored and that effective measures are needed to prevent the increase of ARGs content on maturation stage.202236162559